I’m an electrical engineer, licensed electrical contractor and volunteer firefighter of 35+ years. This is the very best demonstration of the risks posed by a “bad” or missing neutral. It SHOULD be made mandatory training for anyone working in the trade. Thank you!
Yes, a great example. Lost neutral was certainly taught as a very dangerous condition in the UK - tho as we are mostly 240V single phase PME it's more that anything earthed sits at 240V potential if the neutral is lost. When working in the Middle East in a flight training school, the Simulator blew up one day, it turned out that it had also happened before. The SIM Engineer was perplexed because the voltages across the phases were all over the place. When we opened the 3 Phase supply box outside the building, we found the neutral cable had never been bolted in, it was just lying against the terminal - so sometimes working, sometimes not. Says a lot about the engineers who installed it and those that investigated the previous faults!
I worked for electric utility company 36 years and learned all about bad neutrals and repaired many neutrals. When I retired they brought me back a trainer and one of the things I taught was open and bad neutrals. What they caused we called a power surge due to the imbalance of in coming service voltage. This is not to be confused with a power surge that occurs during lightening storms in the south. The purpose of the neutral in a 3wire or 4 wire service is to balance the hot legs. That was the only answer accepted on the final exam. Also many believe it is ok to touch a neural with bare hands. As long as everything is connected properly you shouldn't receive a shock. How ever if there is a neutral problem somewhere you will receive a shock just as if you touched the hot wire. It's all fun stuff but always be careful and ware your PPE. Better to be safe than dead.
You can get a small shock even from an earth wire (not sure how you call it in the US, the protective ground circuit) if it's broken. Almost all electronic devices have filtering capacitors that are meant to leak a small amount of current to filter out high frequency harmonics, and if the earth wire is broken they can't do that and will just charge up and wait to discharge through you.
This happened last night during a wind storm, I was confused as hell, since half the light worked, and the other half were bright as hell. Can't believe we didn't blow any bulbs or anything after 12 hours. Thanks for the explanation! Edit: months later I would learn one of my friends backed into our telephone pole 😂
@@morganinspectionservices3840 Cell phone and laptop chargers connected would like not only survive, but work normally during the overvoltage if they were (as they usually are - but not all are) rated for 100-240V for world use. So they'd run happily on 120, 170, 212 or even 240V or down to 100V. So something surviving and even working doesn't necessarily mean it is getting 120V. So you could plug a laptop charger in and have it work, then plug in a hair dryer and have it explode, and mistakenly not blame the power because ("the computer still worked").
I think he didn’t lose electronics generally because of the dc switching power supplies being able to deal with the slightly higher voltage that’s still below 240. A lot of computers power supplies used to have a manual switch for 120/240 operation, but these days many of them just auto adjust.
@@ericnewton5720 I was wondering if anyone else would comment about just that. Most modern electronics can auto adjust to 120 @ 60hz or 240 @ 50hz. This might even be the case with LED bulbs.
@@ericnewton5720 When faced with a world that has residential voltages between 100V and 240V at either 50Hz or 60Hz, a company is more likely to just design a single device that can handle as many cases instead of a bunch of separate localized variants of the same thing.
My dad worked in the water department of a local city. One day when he was working on a water main, they had to disconnect a house from the main to swap out a pipe. When they disconnected, the pipe sparked and the owner of the house came out yelling about his bulbs blowing. My guess, he and his neighbor shared a transformer, he lost his neutral between his house and pole, and his system was grounded to a water pipe. He was using his neighbors neutral through the water pipe, and my dad disconnected it when he separated the pipes.
I've been working with electricity all my life and never seen anything like this. Really great demonstration and easy to understand. Well done sir. We are never to old to learn and it is a never ending job of learning.
Thank you for sharing this video. It perfectly explains what happened in my house yesterday. Several electronic appliances exploded, and although the technicians managed to fix everything, they couldn't clearly explain the cause. After watching this, I finally understand what went wrong!
I've had to happen to me. A storm broke off a tree limb, which fell and broke the neutral from the transformer. It was a wild ride. My wife and I had a light fixture above the bed with incandescent bulbs in it. When the event happened we both were laying down but we sat up when the lights started going crazy and about one second later the bulbs in the fixture exploded and the glass fell onto our pillows. I jumped out of be do run down and flip the main disconnect but out of habit I hit the light switch for the stairway light. Poof, another bulb blows. I had to grab a flashlight to get to the panel which extended the time it took and I'm sure that caused some of the other devices to fry. I lost tv, vcr, some of the stereo, relay board in the range and who knows what else. A guest staying with us said the vcr was crackling like bacon frying and the tv looked like it was in the poltergeist movie. Honestly I'm surprised more devices didn't fry.
If the neutral on main board were so well grounded with a structural ground on building structure, the chances of damages would be so reduced, I've had a lost neutral too, if my neutral weren't grounded, would be bye bye to my microwave oven and my frost free refrigerator at once.. but fortunately, I did my neutral grounded, it's a *TN-S* system! 😅
thanks for the reply. At 2:10 you said they were phases or legs. That’s two different things. Either way you look at it, it’s a single phase transformer. What we really mean when we mention phasing is time. Are the two legs out of time with one another? No they are not. There is nothing that can cause a delay. So they are in time. An oscilloscope would show a 120 volt sin wave or a 240 volt sin wave with their peaks being at 170 volts or 340 volts. The two legs do not add together to create 240 but rather we are breaking the 240 in half with the center tap. By doing so we are only changing the amplitude of the sin wave. All measurements are relative with respect to reference. My phone always gives an error when replying to a comment so I have to leave another comment.
@@Randall-mt7jkcorrect. One sin wave has twice the amplitude as the other and that’s the ONLY difference between the two voltages. They are the same phase.
Friend bought an old house, old 2 wire no ground romex. Some later wiring added with ground. Got shocked in bathroom, even though had working GFI outlet. It tested okay, but everything supposed to be grounded, was HOT, intermittently. Overhead fixture, device frames, cover screws, etc. After looking around, what was rewired, added over the years. The bathroom had been rewired with floating ground wire not connected back to panel. Along with added ceiling fans in nearby living room. A single tiny strand of hot wire on fan was sticking out of wire nut, touching floating ground wire. Creating intermittent shock hazard whenever fan switched on. Fixing that fault, running ground wire to panel, that problem was repaired. Hard to tell what hazards lurk in walls and attics. Even if things seem to be working.
This is an excellent explanation. You were absolutely correct except at 6:01. It should have been, "instead of turning left". Otherwise, it was perfect. A lot of confusion, conflict, and controversy exist, however, because some folks don't have a proper understanding of the term phase and the different meanings it can have. When you say that the 2 ends of the transformer, or legs, are 180° out of phase with each other, that's correct. They are. That doesn't mean that there are 2 phases in the circuit. A 2-phase circuit doesn't exist. But there are some people who believe they do. There are only single-phase circuits, with the two legs 180° out of sync/phase with each other, and 3-phase circuits. You could build a generator and circuit with more than 3 phases, but there'd be no advantage to it, and it would cost more for the transmission lines. Good job!
Just had FPL out and this was exactly my issue with dim lights with microwave, table saw etc. I always thought it was me replacing with smart switches, omitting 3-way red wire etc. thank you so much for giving me the kick to finally call them out instead of wasting hundreds on an electrician.
Just had another issue with the neutral line going to the transformer on the pole. I had some strange power fluctuations again but not as drastic. So I put my clamp meter on one leg going into my panel. Then I turned every other breaker off putting a larger load on one leg. It showed a voltage delta of about 15 volts. I called FPL and they sent a service truck out. He pulled the meter and put a device on it to check and it showed it was just over the allowed difference. After inspecting the ground cable he saw where my neighbors tree was chafing the wire. It was warn down to a single strand. They replaced the neutral drop and it is now fixed.
Great video. Can you speak to the dangers of having a bonded neutral on your generator versus it being a floating neutral when using it to power your house through a manual interlock? Thanks!
I worked as a cable tech for 16 years. I also worked in a beach area where the grid was copper but all there service lines were aluminum. The two different metals would cause the neutral to fail fairly often. Very dangerous, if you were not careful. Low volt guys get little to no training on this. Most of the time the connection point at the bond would completely melted and that was a dead give away. But sometimes it wouldn't be and if you didn't hit it with your FVD you would get sparks flying when the wrench touched the coax fittings.
My brother had this happen at his house when a lady hit the power pole across the street and he also had a bad ground at the breaker panel which caused the whole house to try and back feed through the 14 gauge ground wires on the furnace and dish washer as one was connected to a gas line and the other a copper water line into galvanized iron water line. Needless to say, I am glad that his daughter skipped school that day as she quickly went back and turned off the main after seeing smoke start rolling out of everywhere. I had to go up and replace all the wiring on both appliances and ended up installing a new ground rod outside along with bonding it to the gas and water lines.
A hint, if your house isn't made of wood, use your iron structure as earthing grid, it's an awesome earthing, and saved me of appliances losses, I'd lose my microwave oven and my frost free refrigerator if my neutral weren't so well grounded on building's steel structure, look for structural earthing, my system is a TN-S.
Thank you so much for posting this video! We had a big wind storm roll through yesterday and knocked out the neutral wire to our home. I wasn't sure why our lights were acting strange; but now I know. Thank you!
Thanks for the good demonstration.This will help other save themself. Can be a very dangerous situation. I have seen this happen a few times. One has to learn this before one plays with it. The fist thing he taught me was to respect it and treat like it is HOT! I was 12 years old Back in the 60's and I was wiring houses with my father. {unknown to me at the time. When he was in the USN he was a an EM and also was an electrical instructor. I wounder way he had all those books around that I read.) As a teenager I joined the USN and was an Electricians Mate and advanced right to C school. and Aced it was not much to right home about. Skipped A school all together. Any navy guy knows what that is. later in life acquired a BS Electrical Engineering. Build power plants and switch yards and control yards. Sorry about ringing my own bell. May next do 3 and 4 way switches. I just shake my head at times when it's not understood by someone that call's themself and electrician.
So true. Thank you for your service. I too am former navy. Nuclear propulsion officer on the submarine USS Florida back in the early 90’s. Learned a lot about electricity doing that.
Depends on how you ground your neutral wire, if you don't have an wood house and use your steel structure as earthing grid, and earth your neutral properly to your structure (I did my connection welding, so no bad contact never), your neutral never gonna become a HOT wire, I did my system as a TN-S and it saved my appliances from the lost neutral on public electric grid, I'd lose my microwave oven and my frost free freezer if my neutral wire weren't so well grounded, and guess what? My kind of earthing creates a Faraday's cage, never gives a shock inside my building perimeter, even if happen a direct short circuit on structure, I tested, it's like the phase's potential vanishes on ground.
Wow Tgis video is super educational and solid information. Tgis is great to know. And recommend it to be tougt to anyone wanting to get into the electrical trade. I appreciate it.💪😎
I’ve had that happen at my house during a hurricane. A tree fell on the drop to the house separating the neutral. As soon as the lights went bright I knew what happened and ran to secure the breaker. It took out the refrigerator, microwave, oven, dishwasher and clothes dryer. Completely fried three surge protecting power strips and burned out a bunch of light bulbs.
Yes, it can be very destructive to electronic equipment. Good thing you knew enough to recognize what was happening and shut off the power as quickly as possible.
Damaged the dryer? Wow. They use 240V usually, but some use 120 also to run some circuits, if that side goes high it could do damage. If it goes low, not so likely.
@@franklofarojr.2969 It fried the circuit board. I replaced it with an old 1980s dryer that has been refurbished. No electronics works better than any new dryer I have had.
I already had a Neutral lost, but luckily, I've previously grounded my neutral mains cable to the house's iron structure, doing an structural TN-S earthing system, so even with a lost neutral, the internal cable that was neutral didn't gave any electrical shock, even during a test with all appliances out the outlets and purposely shorting one live leg to the grounded wire, the phase wasn't able to give any shock while connect to the structure, I was like the potential had vanished to the ground, I know it's actually the Faraday's cage effect inside the building, only a perimeter circulating grounding like the case of using the steel structure can do this effect, but about the appliances, I had an air conditioner working on about 120v on one leg, and a microwave and two refrigerators on other leg, but the microwave was on standby, the current on kitchen was lower, so if my neutral wire weren't so very well grounded, I'd lose my microwave and my electronic controlled frost free freezer. It's so important *ground the neutral wire* very well, this can save you during neutral losses or even when a high voltage wire hits the neutral on road.
Not only that. As the neutral is bonded to the ground wire the voltage on the neutral gets to any grounded equipment case. This could in worst case kill. Here the instruction is to get out and call the power company and not to return until it is fixed but we have higher voltage.
I don't know about US but in Czech (EU) you have to have 3 wire system and connecting neutral to ground is forbidden. Yes there still might be old houses to have it but in own interests should rewire it asap. Also every house have to have "ground protector" which measure current leak from main to ground and Tripp in matter of milliseconds.
@@VavrMar You mean the ground wire? That is known as TT. It is used in many countries in Europe. Others use TN-C-S where the ground wire connects to the neutral at the entry. Such a system does not require RCDs to work though they now are mandatory as additional protection.
@@VavrMar It's because one ground rod never gonna be enough to ground the neutral and still be safe even on a neutral loss, the only kind of earthing that remains secure even with a neutral loss is the *structural* one, the kind that use your building's steel structure, and have to be a so well performed connection, welding, this kind of earthing creates a *Faraday's cage* and is the only secure option to use *TN-S* system, my installation earthing is TN-S and is secure, I had a neutral loss but nothing on my house gave any shock, because more important that just grounding, is equalizing, and my structure is literally a *Faraday's cage* and I didn't had any accident, and it even saved my microwave oven and my frost free freezer of having their electronic circuit boards fried!
maybe this is a better way to explain and understand. If you remember ELI the ICE man we know that a reactive load causes voltage and current to be out of phase with respect to one another by some amount of angle. That is to say they are out of time with each other. Voltage happens first or current happens first. This is because a capacitive circuit delays the voltage and an inductive circuit delays the current. With 3 phase, the 120* angle between each phase comes from the power company with their generators being 120* out of sync with each other. In the case of a single phase transformer secondary, this is not a load but rather a voltage source. There is nothing in it that would cause a delay in time. I did watch your video and your meat and potatoes of what you’re explaining is spot on. It’s just that when things are taught with misunderstandings, it causes confusion to set in and the confusion gets taught to the next group and so on. When I studied in the 90s I went above and beyond what was taught in the classrooms and I missed a lot of test questions because of it. One that I remember was marking a question false that said current can only flow in one direction through a diode. I knew how a voltage regulator works by flowing current through the diode backwards so I marked it false. My teacher had no clue what a zenor was. I’m an hvac contractor now and work with electricity every day but I’m not an electrician. Sometimes I wish I’d learned that trade instead.
Whatever you are, you sound like you really know your stuff. I was guessing you were an electrical engineer. I honestly have always heard and believed, and therefore thought that the two 120 V legs were 180 degrees out of phase. I learned that because of one being wound clockwise and the other being wound counterclockwise that they are 180° out of phase, and that makes total sense to me. You have gotten me to thinking, and I am going to do some more research, and get ahold of an oscilloscope. I will probably make a new video based on this discussion and what I learn. I hope to talk to you more.
I had a bad neutral at the transformer. The symptoms were a voltage difference between the phases. I showed the lineman the voltage differences, but he didn't seem to believe me. Took the bucket up to the transformer and shook the neutral. A shower of sparks confirmed the diagnosis. They replaced the transformer.
Thanks Mike. I’ve done heat and air most of my career and started my own business 5 years ago. I’m near Memphis. I struggled with this very concept but the guys at our local power company are the reason I understand it now. I’ve been up there several times early in the morning when they get there to start their day and pick their brains. There are still concepts I don’t understand so I’m always learning. For example, nowadays they are teaching that voltage is not a force and I’m really struggling with that one because that was the entire basis of electricity when I studied in college back in the 90s. Electromotive force = voltage. I really struggle with computers. I don’t have the patience nor do I understand all the errors I get. With an electrical circuit, a switch energizes a load. When you apply voltage to that load, current WILL flow and the circuit WILL work. Sort of like pressing a key on a mechanical typewriter. You press the key and the hammer WILL hit the paper. With a computer, you give it an input and a thousand things have to happen before the computer decides to energize the load. Or you press a key and the computer receives a request, thinks about it, and decides if it wants to respond. I hate computers and right now I’m frustrated because I’ve tried again for about an hour to figure out how to respond to these comments and I get an http status error 400 error when I reply. Nothing on TH-cam or Google has worked. I’m using an iPhone 15 pro max that is 3 months old. But yeah I’d love to see you do a video on this. I’ve done a couple videos myself but I don’t know how to use the computer to do the animations and stuff and I don’t know how to edit a video so mine are just one take and they were just on capacitors proving that current can flow through them. Experimental stuff. I’ll subscribe so I can catch it.
Well, I have an engineering degree, but I’ve been a home inspector for the last 22 years. I love learning and I love teaching. I have learned that I love making animations and I’m trying to make better and better videos. I’m getting older and spend almost all of my free time working on new videos because right now it is my passion. I often have to learn things before I make my videos so I can sound like I know what I’m talking about. You have inspired me to continue on. It’s been good talking to you.
I understand your misunderstanding. I have generally been in the automotive field and know that a hot & a ground makes 12 volts. Hence, an electrical component works. Occasionally, the addition of a resistor or relay change that basic Hot/Ground logic. No problem , I'm still on board. Then came the computers. I throw my hands up and say, nope, ain't gonna try to understand. Well , then I dabble a little and get a tiny understanding. Don't trust my logic on this, and I gladly stand corrected if I'm totally off base. Your observation of flipping a computer switch and it simply sends a signal is correct , IMO. In my world (automotive) , the revelation came to me from watching a college student explaining their "Robotics" class. The student went into Can Bus theory. Can Bus ? (maybe I've spelled it wrong) , where have I heard that before ? Yep , in newfangled automotive electronics diagnosis. Can Bus - High. Can Bus -Low. From my understanding, the Can Bus system runs on 5 volts or less. The Can Bus system goes through a system of checks of this, and that before energizing the desired component. All sensors sending signals ? Seat belt fastened ? You get the picture . From what I understand, Can Bus High generally operates critical components. Ignition, fuel supply , Etc. Can Bus Low generally operates secondary components. Seat belts , heated seats , radio,Etc. Going back to the Robotics class theory. A robot, theoretically, cannot move its right leg until it receives a signal that it has already moved its left leg in a walking scenario. Cars are now robots. The car will not start (hypothetically) until it receives a signal that the seat belt has been fastened.
Got called out on a washing machine having problems finishing the cycle. When i got there i turned it on and the laundry room light got super bright. The washer motor was overheating from low voltage. Neutral was broken at the main entrance.
I can’t imagine that it would change anything. Surge protectors are designed to shunt very high voltages. 240 or 250 V would not even be detected by a surge protector, I don’t believe.
Took my electric company sending 6 guys out over months to figure out they had never tightened my neutral in my meter panel. Whole time they blamed me. Took a new guy to find it and replace it.
I think that problem only happens in countries using 120 volts because they have three cables going to their house from the transformer (+120v, 0v, -120v). In countries using 240 volts that's not a problem because they only have two cables going to their house from the transformer. If they lose one of the cables the light won't turn on.
Yes, you are correct. It only happens in countries where the voltage is split at the transformer, so countries that only use 220 or 240 V do not encounter this same problem.
@@morganinspectionservices3840This sort of thing does happen in countries using 240V systems, because the distribution is 3-phase. Factories, apartment blocks and other large premises get a 3-phase supply (that is supposed to be 415V between any two phases and 240V between any phase and neutral) and most houses get one of the three phases, rotating from house to house along the road. Loss of the neutral causes different voltages on the different phases according to the loads on them, and you can get things burning out because of excessive voltage.
Few countries use 240 V. Most of Europe is 400 V three phase and the same thing can happen. With 240 V there is another problem. Remember the neutral and ground are connected. What is in the neutral will be on the equipment cases. In single phase 240 V that is full 240 V. Now one can avoid this by not connecting the neutral and the ground and relying on RCDs. In the UK EV charging points need to be protected against the broken neutral or PEN-fault as it is called there. This can be done by using a ground rod for ground. As it is RCD protected it will be safe. There are also more sophisticated methods.
We had this on a 3 phase 240 V European system. Something was blown at the transformer and the lights were dim. We had a heavily loaded phase with the dishwasher turned on where everything survived and two almost unloaded phases where many power supplies were blown. Since most switching mode power supplies can operate on 240 V without issues it's not a huge issue in the US nowadays, but here in Europe we get over 400 V which blows most of the power supplies. Luckily if it's manufactured correctly the high voltage will make a component short to the earth (and sometimes a capacitor will also blow up), protecting the electronics behind so only the power supply needs to be replaced.
@@okaro6595 In all the US service panels I have seen, it is impossible to separate the neutral from the ground, electrically, unless you insulated the neutral bus bar from the panel, and I would think that would be a code violation. I was wondering as I watched this if the building ground wouldn't mask a lost neutral, as the neutral is also grounded at the pole. Granted, many if not most buildings have inadequate grounding, but I would think that in a properly grounded system it would be impossible for a lost neutral to cut all current flow on the neutral on the building side of the system.
One thing that I didn't see really mentioned, though no real good electrician would run into this problem, is that the "neutral" of the right side of the circuit will now be positive with respect to ground. So if you think you can touch or work on that neutral and be safe, you better think again
Very true. I do think I mentioned somewhere that there can be voltage on the neutral. I did recently release a new lost neutral video. It specifically covers and even measures the voltage on the neutral.
Call the power company as the problem is their neutral. If you call a electrician you will be stuck for service call $ , and they don't work on power company lines.. This could be over $100 for a minimum call The power company will service and fix the neutral connection.no charge. These electrical neutral problem s are dangerous and eerie. Our aluminum framed screen porch was measuring 40 to 70 volts. My dog yipped as she went outside because the aluminum frame and door was electrified. I put my fluke black lead into the nearby ground (soil) and the red lead on some aluminum - ac voltages were all over the place. I think the electricity found a ground but also found a ground that energized the aluminum frame which was also grounded. 😮😮
There's an issue with your grounding system, on my house, my steel structure is the grounding grid, if I short one phase to it, the phase potential vanishes on earth (Faraday's cage effect) and I can even touch the grounded phase wire with my bare hands during the test, so my ground grid is secure to do a TN-S system and it's what I did, on day I've lost my neutral, my ground and neutral wire on my internal installation didn't got electrified, I could touch the appliances metal cases without getting shocked due the*Faraday's cage effect* what prove structural earthing is secure, but also has to be done properly, and this is what I done, my connection to structure is welded, never gonna be lost.
Interesting video...I'm in the UK and often wondered how you guys managed to have both 120v and 240v in the house. Out of curiosity, if a customer has a lost neutral, could it be detected by plugging in a simple GFCI tester in the outlets? Also, do you guys have a separate ground/earth/CPC wire in your electrical ccts?
Nice video. Power company came out today and ran a temporary neutral to my meter and they will bury wires in a few weeks. Have had flickering lights for some time.
Interesting. Here in UK the consideration is typically diverted neutrals because of subtle differences in the way you & we feed supply current. In the UK case it's where neutral currents end up flowing in the ground/earth/protection wiring (as most distributions have repeated connections to Earth).
does this prevent or mitigate the issue or is the issue just happening differently? i sound stupid i know but apart from being able to wire a plug i am an electrical idiot.
@@mysterycrumble In the US system you have two live or 'hot' feeds which are anti-phase (opposite polarity) so that you can have ~240V power hungry devices connected between them. When you 'lose the neutral' then you have your two sets of 120v loads connected in series, so 240V, without the neutral stabilising the 'mid point' voltage at zero (the two hots being +120 and -120v relatively speaking). At this stage the weaker side of the two hots tends to 'blow' from having over voltage, and hence on that spur, over current. Meanwhile back in UK we have far more domestic circuits distributed from local substations where the neutral and earth are connected for multiple household supplies (often US supplies being a local transformer so only one or two with the common neutral/earth at the supply pole). so.. Now with our older infrastructure we have more cases where the supply cable has lost the neutral ("broken PEN") and instead the local 'earth' conductor is doing the work of the return path. And that return path (i.e. the whole supply current for other properties & services that neutral also fed) can prefer to run through your household earth wiring, especially if you have rock solid earth bonding, earth rods, copper water piping etc. An example could be the (faulty) street lighting that is seeking to return via your household wiring which isn't sized to carry such currents. Also makes for EV charger risks (an outside power point nearer the street light than the house) requiring extra detection for spurious earth voltages and sneak current paths and multi-way isolation). Everything is great when it works as designed. We're just getting better at being concerned about real world faults!
Back in the 1970s, at a railway locomotive shed owned by a railway preservation society in Britain, an idiot decided to turn off the yard lights by removing the neutral link on the lighting fuseboard (3-phase 415V supply), with the result that there was an immediate cascade of blown lamps.
EXCELLENT object lesson. I'd be curious to know what would happen if a UPS (Uninterruptable Power Supply) were wired in place of one of those light bulbs, and that lightbulb was plugged into the UPS. If each lightbulb had its own UPS, would they be protected from burning out?
The UPS would likely protect the lightbulbs from burning out because once it detected the voltage fluctuation, it should either shut down the power to each individual lightbulb, or switch over to battery power, depending on how it is designed to operate.
The current flow at 3:45 is backward for a balanced load with no neutral current. The diagram shows the neutral current as additive when it should be subtractive.
I had to go back and watch the video. I’m not following you because I am showing balanced loads on the two legs and then no current flowing on the neutral so I am showing it as subtractive. Please explain a little more and we can discuss this.
A few years back went on a service call where the homeowner had smoked up a flat-screen, DVR, and stereo system after a 1500 watt electric fireplace had been running for about an hour. It was a lost neutral on a MWBC feeding the master bed & living room with backstab connected receptacles. A backstab connection upstream burned out on the neutral. Home was built sometime in the 1970s if memory serves me right. This expensive ordeal would have been avoided had the receptacles been installed in accordance with 300.13 (B) which states the neutral of a MWBC cannot be interrupted by removing a wiring device.
Thankfully, I live in Chicago, where everything (almost) is in conduit, and MWBCs are not as common, especially in older buildings. I do run into hack jobs where someone had scabbed in an illegal 14 or 12/3 'BX' and either ran both legs on a tandem or 2 separate breakers where the handles were not tied together. The Chicago NEC upped the allowable length for 'BX' to 25' from 6' (whips) for 'enclosed/protected' spaces. I expect to see more problems popping up as people (either DIY or remodeling cos.) run new circuits without the knowledge of how to do it properly and/or use 'backstabbing' on devices.
I got these symptoms but no electrician was able to diagnose. I had to change many cables hoping the problem went away, and yes, at the end it was a broken cable coming from the street. The more you know
This is so important. Thank you for causing a bit of fear and interest in abnormal electrical workings. I remodel and occasionally wonder why strange things happen. Thank you.
An open or high resistance neutral conn in the panel or meter can will also cause this. Not always upstream. I've been on many trouble calls where the nipple between the two was glowing because of a loose neutral in the panel. Some were never actually tightened by the original installing electrician.
Great info. I guess when I said upstream of the panel, I actually intended prior to any of the branch circuits, so yes the neutral lug on the panel would certainly qualify. Thanks for the clarification.
@@morganinspectionservices3840 You are correct though. Probably 90 percent of my trouble calls were due to homeowners allowing trees to grow up into the service wire and either breaking the neutral, or rubbing it in two midspan on the drop. People don't understand that the power company isn't responsible for their negligence.
This is a good video, but how does this work with grounding? Isn't the neutral bonded to ground at the panel? How would that affect your diagram and your demo circuit?
Hi. Thanks so much for watching and thanks for the question. Grounding really does not affect this because the Earth has such a high resistance that you will have a small amount of current flowing down the grounding electrode conductor to the ground rod, but it will be very minimal and will have almost no effect on what I am showing. However, all of the ground wires running from the receptacles and lights back to the panel will not be at 0 V. They will be at a voltage that is determined by calculating the difference between the voltages on the two legs and dividing that by two. So let’s say you have 180 V on one leg and 40 V on the other leg. You’ll have 70 V on all the ground wires in the home. This obviously makes a lost neutral, extremely dangerous. I re did this video several months ago to include this. Here is a link to that video. th-cam.com/video/YY5Fur7S-KE/w-d-xo.htmlsi=8XB2134lleqX_Yb7
Now can I ask an electrical engineer a question. It has always seemed to me that AC voltages of 120 or even substantially lower are very easy to get shocked from, but DC current don't seem to be this way at these voltages. What I am asking is this, is messing around with batteries that are 90 volts or 130 volts a dangerous shock hazard? Landline telephones operate at 60 volts DC power. Antique 20's era radios had battery banks that operated up to 135 volts. I have been powering old radios like this by putting together 9v batteries in series to about 90 volts but have always been a little leery about the safety of handling such things. I have carefully tested lower DC voltages on the back of one hand and couldn't seemingly feel any current. I have somewhat assumed that 60volt DC may not be quite as dangerous for the simple fact that phone wiring is pretty wide open in the public sphere. Could someone clarify this. I have looked quite a bit online a few times to try and find some discussion of this.
I will start off by saying that both AC and DC voltage can be dangerous and fatal, however, the human body seems to tolerate DC voltage better. One study I read says that the human body can withstand approximately five times the DC voltage than it can AC voltage. If this is correct, then it would take approximately 600 V DC to give the equivalent shock that 120 V AC gives. AC voltage, which is alternating current, seems to affect the body more than direct current does. Alternating current has a greater tendency to cause atrial fibrillation than DC voltage does. The human body seems to have a higher impedance (resistance) to direct current than it does to alternating current. Having said this, every body is different, and low DC voltages can sometimes be fatal to some people.
When I was building electric cars 35 years ago, I got shocked by a 72V DC battery pack. Not bad, but shocking. It's about as bad as getting hit with az24V AC (thermostat or sprinkler valve). I can feel 42V DC as well.
I was taught it takes approx 40v before you feel anything, having said that, the current is what hurts you so it depends on the power supply. For example, static electricity is thousands of volts but is very low current so you feel a “pin prick” at worse. The North American public telephone system was around 40v DC (?), it gave you a bit of a buz under the right conditions enough to feel it but no kill you (depended on individual circumstances, humidity and skin resistance). The path the current takes in the body is most important too. If in doubt and you must touch the wires, I was taught to use the right hand thumb and index finger or just one finger, the idea there is that the loop urgent would be localized and not travel through the body across the chest through the heart down to the legs into the ground. Current needs a path through you to another conductor, usually ground in most cases of shock. Having said all this, the safe way is to not touch wires above 30v (I was taught that) and gamble with fate, there’s enough testers out there to safely indicate live wires.
Generally voltages below 50 V AC and 120 V DC are safe in case of an accidental exposure. The primary safety method is always to avoid the exposure. Laptops operate at 19.5 volts because 20 V has been considered the limit below it is safe. If you operate with 90-130 V treat it like it was mains voltage like have no exposed contacts.
Worst case scenario from a floating neutral at the service drop could be electrocution from energized water pipes and metal case appliances with 3 prong plugs, because until I believe the 1978 NEC, a cold water pipe could serve as the sole grounding electrode if at least 10 feet was in contact with the earth, and the connection to the grounding electrode conductor is made within 5 feet where it enters the building, and plastic pipe could have been used to replace a section of corroded metal pipe. Because the neutral and ground are bonded at the main service panel, a double loss of ground and neutral could have lethal consequences. To combat this, a water pipe used as a grounding electrode must be supplemented by grounding electrodes in contact with 8 feet of earth with a resistance not to exceed 25 ohms.
Water pipes still are bonded and that is for safety. In case of broken neutral you do not want 120 volts between your stove and the water tap. It is safer to raise the potential of the water pipe.
No. When your service loses a neutral, nothing done at the panel that I can think of will change the fact that you will have the two legs in series on a 240-volt service.
If neutral is still bonded to ground, the ground can serve as a return path to the transformer, though it's not an efficient path due to earth's high impedance.
Great video, I have been having problems, I had the electric company come out they said on their side it good, so I bought a multimeter and sure everything is good until I turn on the microwave on certain days some days the microwave doesn't change anything and other days it makes the fan speed up so I go to the meter pole and leg L-1 is 132 and L-2 is 117 so is the problem on me or electric company and could the bad neutral come from half a mile away i don't share a transformer i live way out in the mountains.
You definitely have a lost neutral. However, the symptoms are the same whether it’s on your side or the power company side, so it is impossible to say where the problem is originating. It’s just going to take some investigation. I will tell you this that you would not be the first person I have heard of the power company saying that it’s not their problem and then later discovers that it is. And the reason that you have the problem on some days and not on other days, depends on the load distribution of what is currently running in your home. If you have a heavy load running such as air conditioning,clothes dryer, or things like that, then turning on the microwave will have a much smaller effect on the voltage than it will when very few things are running. I wish I could help you more, but long distance troubleshooting is very difficult. If you can give me any more information, I will help you as much as possible. I would definitely be interested in hearing what you find.
@@morganinspectionservices3840 Thank You so much, and I will give the update of the cure if I ever find it, today I turned everything I could find to bring one leg down, but it would only drop 2 points, the kitchen is on leg 2 so I had hot plates refrigerated, space heater , L 1 at the meter pole showed 120 L-2 showed 124 nothing was running on L-1 but in a few days seems it is usually a hot day it will actually up again. I can measure the house or at the meter pole it's always the same, I was told if the legs are unbalanced at the pole it would be the electric company problem.
You will have some current flowing from the panel into the earth due to the groundingelectrode conductor. Since the earth has a high level of resistance, there will not be a lot of current flow, but probably a few amps.
@@morganinspectionservices3840 Thanks for your answer and this great video. But I'm still a bit confused. What then is the purpose of connecting the panel neutral bus bar to a local ground rod?
@@hueywallop2461 ---- the neutral busbar shouldn't be connected to the ground rod. The neutral busbar should be connected to the neutral from the meter. The ground wire comes from the ground rod and either cold water pipe before the shut off valve(residential) or building steel (commercial) and up into the service panel hitting a ground hub on the connector used for the ground entrance into the panel then to a ground busbar or to a ground lug attached to the panel box with a nut and bolt or a hole that has been tapped with threads for a screw to tighten into.
For demonstration purposes this is an okay way to explain it, but this is the reason that the NEC doesn’t like you to share neutral wires anymore for a long time now. The 240v circuits would single phase but that should trip the breaker because of unbalanced loads to protect them, this is also the reason that you are supposed to balance your panel loads. This explains better what happens when you lose your neutral from the power company, but not really what happens to individual circuits in your home, but it’s a good simplification of the situation.
Yes, it was only a demonstration to show what happens when you lose your neutral from the utility company. But yes, I guess it also demonstrates why shared neutrals are not a good idea.
Great demonstration! Is there a monitoring unit that you can install on your load centre that would cut power the instant neutral was lost, for example due to a fallen branch in a storm or perhaps an ice storm?
@morganinspectionservices3840 I envision that it would be simple. Perhaps monitoring neutral to ground in a strategic location outside that would pass a small current and when that current stops, you could have a lost neutral condition.
@@morganinspectionservices3840 Problems of that kind are very dependent on country and distribution system, so it is context one needs to know before voewing a video like this.
The three (3) bulbs on either leg are wired in parallel. (Although the two (2) legs are now in series to each other with the lost neutral.) When one bulb is turned off, the Resistance goes up and the Current goes down (in that leg) because they are in parallel. Naturally the leg with the highest resistance (series circuit) has the highest voltage drop.
"When one bulb is turned off, the Resistance goes up and the Current goes down (in that leg) " - i understand that resistance goes up if we swich off 1 light in the circuit because its parallel so it is as if we closed 1 of the 3 roads for the current - so more resistance. More resistance means less current in that leg but both legs are in series so the current is the same. So if the same current is flowing while the voltage is much higher means that a lot more energy is on the side when 1 light is off. Does it make sense the way i rephrased it?
8:48 damn i really need to go back to school, but why is the resistance higher with 2 lights compared to 3? Isn't light burning cause it has a resistance so if you remove 1 of those resistances how is there more resistance all of a sudden ?
With three lights on you have three equal paths for the current to flow. With only two lights on, you only have two of those paths for current to flow. The more paths, the lower the resistance.
I had a shared neutral on 6 plugs in my garage. A wire nut failed and I had a lost neutral in my house but just on 4 plugs. It destroyed a charger before I noticed the problem.
If a neutral becomes disconnected inside the home, then that’s actually a different situation than what this “lost neutral“ video discusses. We typically call your situation an open or disconnected neutral. I have a separate video on that. Sounds like you were already able to solve the problem. However, if you need it, here is a link. th-cam.com/video/BVcNnBKfC8Q/w-d-xo.htmlsi=7Gb7tGew_n87GCKy Temperature
@morganinspectionservices3840 That video did a good job describing a lost neural on a 120v circuit. I’m referring to a shared neural. Which acts more like this video. So imagine this. You install a 240v circuit breaker. Then you take a 14-3 from the circuit breaker box to an electrical box with 2 receptacles in it. So going into that box you have red, leg1; black, leg2; white, which is a neutral shared between the black and red; then green, your ground. Red goes to a 120v plug on the right. Black goes to 120v plug on the left. Both plugs have a pigtail going to the single shared white wire. Now disconnect that white wire inside the electrical panel. Plug a lightbulb into both 120v sockets. The energy follows this path. Black wire Light bulb White pig tail Second white pigtail going to the other plug Second lightbulb Red wire So you have 240v going through 2 120v lightbulbs. Being protected by a single 240v breaker. Now you have your demonstration but inside a house. Fun fun watching things smoke. 😁
what is the impact on the consumer meter reading if in a three pages meter, neutral wire is directly connected from supply to the wire of consumer i.e input neutral is not connected to the meter input and neutral output of meter is not connected to the consumer neutral wire? Pls note the three phases are still connected via the consumer meter.
Hi! Hope i didnt miss anything in the video, but what would happen in this situation if the electrical supply ground was lost but your neutrals and grounds were (obviously tied somewhere) tied in the panel and you had a good ground rod out side (obviously tied to your ground, and neutral bar if they were tied together)? would the rod them act as your neutral and help alleviate the situation of a lacking neutral? And if it did, would it affect grounding safety through your house? thanks!
The ground rod would not act as the neutral because it does not tie back to the transformer. Some amount of current would flow through the grounding electrode conductor, through the ground rod, and into the ground. However, the earth is a very poor conductor, so the amount of current flowing would be limited. I would estimate 4 or 5 amps only. As a result, the voltage difference between the two legs would be lowered to a degree, but not by a lot.
A small amount of the current does go to ground, but the earth is a good insulator, so the current is fairly low. I cannot say how much, but I would guess that less than 5 A will go to ground.
Thank you. I don’t know of any way to detect it other than noticing lights dimming or brightening, or other things running faster or slower than normal.
@@morganinspectionservices3840 thanks so much. Can I ask you a different question q: so in this guys video here ….is he talking about a “lost neutral” or a “floating neutral” ? He calls his video “floating neutral” but after watching it I realized…..he is talking about “lost neutral” right? And why is his system diff from yours? His has 3 homes connected to the secondary but in America we only do one? So 3 phase means 3 homes and 1 phase means one home ? m.th-cam.com/video/b9hDHGxaufM/w-d-xo.html&pp=ygUQRmxvYXRpbmcgbmV1dHJhbA%3D%3D
Thanks for the video. I tested the plugs of my home and I found that a few plugs have 50v between neutral and ground (220v power supply) , may I ask why the voltage is not zero between neutral and ground lines?
Are the outlets where you’re getting the 50 V close together where they could all be on the same circuit? If so, it’s likely that there is a bad neutral connection somewhere so you’re getting some resistance on the neutral wire. As current flows through the neutral wire, you will get a voltage drop, which will put some voltage on one side of the neutral.
@@morganinspectionservices3840 Thank you. I guess they are in the same circuit. Btw, would that be a hazard if it is a bad neutral connection that I should be concerned?
@@erihsehc2 It certainly can be a hazard, but it’s not definitely a hazard. It just depends on exactly what’s going on. Loose connections can result in arcing which creates heat which can result in a fire. It also puts voltage on neutral wires switch can, under certain conditions, cause somebody to get shocked. If you’ve done any electrical work and feel comfortable, you could check the affected receptacles to see if there’s a loose connection there, or it could also be in the electric panel where the wire is connected to the bus bar. Best thing to do would be to call an electrician.
Partial 'lost neutral' can be caused by having an inadequate ground, such as a grounding rod that is too short and in a rocky base (such as your grounding rod going into dry limestone).. also, this is why fueled gensets have a neutral grounding post..
The lost neutral and poor grounding should have nothing to do with each other. In fact, there’s a lot of older houses still around without a ground rod. Typically the ground lack of a ground rod doesn’t cause a problem - unless there’s a voltage spike or some transient voltage on the powerlines.
It's called an 'Open Neutral'. And yes, it's the most important connection in any system that has a Neutral. Always identify and connect the neutrals first when doing any kind of switching,controls,loads to minimize problems. If you make a mistake the circuit/logic may not perform correctly but at least if the neutals for the loads are connected the chance of a dead short or a shock are greatly reduced. The neutral is the most important connection.
How would you get a lost neutral condition? Don't these circuits typically have independent neutrals back to the breaker? Also I thought the neutrals and grounds are bonded at the breaker panel.
A lost neutral occurs before the breaker panel. As a video explains, a lost neutral can occur anywhere between the transformer and the breaker panel. Maybe the neutral gets corroded or pulls loose at the weatherhead. Maybe a tree rubs on it, and overtime breaks it. There is also a situation called an open neutral, and that’s something that affects an individual circuit or a portion of a circuit. That is a very different situation.
This happened to me and it smoked every 120v transformer and motor in my house, including the hvac blower. What a pain that was. Even the refrigerator fan, and it took me a few months to even realize that one.
Even worse in my opinion is when this fault occurs and the return current finds its way back through the equipment bonding conductor tied to utilities, e.g. catv. Imagine the grounded shield on catv carrying back dozens or more amps. Whole home bonding junctions are a good thing but this is what can happen more easily now.
I’m an electrical engineer, licensed electrical contractor and volunteer firefighter of 35+ years.
This is the very best demonstration of the risks posed by a “bad” or missing neutral.
It SHOULD be made mandatory training for anyone working in the trade.
Thank you!
EE, as well. I was fortunate to be there in the early 80s before the curriculum started to change to microchip design, etc.
Wow! Thanks so much for the feedback and comment. I really appreciate it.
Yes, a great example. Lost neutral was certainly taught as a very dangerous condition in the UK - tho as we are mostly 240V single phase PME it's more that anything earthed sits at 240V potential if the neutral is lost. When working in the Middle East in a flight training school, the Simulator blew up one day, it turned out that it had also happened before. The SIM Engineer was perplexed because the voltages across the phases were all over the place. When we opened the 3 Phase supply box outside the building, we found the neutral cable had never been bolted in, it was just lying against the terminal - so sometimes working, sometimes not. Says a lot about the engineers who installed it and those that investigated the previous faults!
I worked for electric utility company 36 years and learned all about bad neutrals and repaired many neutrals. When I retired they brought me back a trainer and one of the things I taught was open and bad neutrals. What they caused we called a power surge due to the imbalance of in coming service voltage. This is not to be confused with a power surge that occurs during lightening storms in the south. The purpose of the neutral in a 3wire or 4 wire service is to balance the hot legs. That was the only answer accepted on the final exam. Also many believe it is ok to touch a neural with bare hands. As long as everything is connected properly you shouldn't receive a shock. How ever if there is a neutral problem somewhere you will receive a shock just as if you touched the hot wire. It's all fun stuff but always be careful and ware your PPE. Better to be safe than dead.
I appreciate you watching, and I appreciate the feedback. It’s always a nice to hear from an from an expert in the field.
Great 👍 advise and we'll said
Wow.
You can get a small shock even from an earth wire (not sure how you call it in the US, the protective ground circuit) if it's broken.
Almost all electronic devices have filtering capacitors that are meant to leak a small amount of current to filter out high frequency harmonics, and if the earth wire is broken they can't do that and will just charge up and wait to discharge through you.
@@demoniack81 or high leakage earth's especially on servers and pcs earthing arrangement
Absolutely fantastic animation and demonstration.
Great explanation. I think I finally understand how this lost neutral thing works.
Understood open neutral but your explanation of Lost neutral was an education. Thank you!
I’m glad it helped!
This happened last night during a wind storm, I was confused as hell, since half the light worked, and the other half were bright as hell. Can't believe we didn't blow any bulbs or anything after 12 hours. Thanks for the explanation!
Edit: months later I would learn one of my friends backed into our telephone pole 😂
Wow! So you didn’t lose any electrical equipment in your home? If not, you were very lucky!!😊😊
@@morganinspectionservices3840 Cell phone and laptop chargers connected would like not only survive, but work normally during the overvoltage if they were (as they usually are - but not all are) rated for 100-240V for world use. So they'd run happily on 120, 170, 212 or even 240V or down to 100V. So something surviving and even working doesn't necessarily mean it is getting 120V. So you could plug a laptop charger in and have it work, then plug in a hair dryer and have it explode, and mistakenly not blame the power because ("the computer still worked").
I think he didn’t lose electronics generally because of the dc switching power supplies being able to deal with the slightly higher voltage that’s still below 240. A lot of computers power supplies used to have a manual switch for 120/240 operation, but these days many of them just auto adjust.
@@ericnewton5720 I was wondering if anyone else would comment about just that. Most modern electronics can auto adjust to 120 @ 60hz or 240 @ 50hz. This might even be the case with LED bulbs.
@@ericnewton5720 When faced with a world that has residential voltages between 100V and 240V at either 50Hz or 60Hz, a company is more likely to just design a single device that can handle as many cases instead of a bunch of separate localized variants of the same thing.
My dad worked in the water department of a local city. One day when he was working on a water main, they had to disconnect a house from the main to swap out a pipe. When they disconnected, the pipe sparked and the owner of the house came out yelling about his bulbs blowing. My guess, he and his neighbor shared a transformer, he lost his neutral between his house and pole, and his system was grounded to a water pipe. He was using his neighbors neutral through the water pipe, and my dad disconnected it when he separated the pipes.
That's a very interesting example of how a lost neutral can be present and affect a whole circuit!
I've been working with electricity all my life and never seen anything like this. Really great demonstration and easy to understand. Well done sir. We are never to old to learn and it is a never ending job of learning.
I'm glad you found it helpful. I appreciate your kind words!
Thank you for sharing this video. It perfectly explains what happened in my house yesterday. Several electronic appliances exploded, and although the technicians managed to fix everything, they couldn't clearly explain the cause. After watching this, I finally understand what went wrong!
I’m glad it was helpful. I appreciate the feedback.
You’re great at explaining things and very well spoken. Nice job and thank you.
Thank you. I appreciate it.
I've had to happen to me. A storm broke off a tree limb, which fell and broke the neutral from the transformer. It was a wild ride. My wife and I had a light fixture above the bed with incandescent bulbs in it. When the event happened we both were laying down but we sat up when the lights started going crazy and about one second later the bulbs in the fixture exploded and the glass fell onto our pillows. I jumped out of be do run down and flip the main disconnect but out of habit I hit the light switch for the stairway light. Poof, another bulb blows. I had to grab a flashlight to get to the panel which extended the time it took and I'm sure that caused some of the other devices to fry. I lost tv, vcr, some of the stereo, relay board in the range and who knows what else. A guest staying with us said the vcr was crackling like bacon frying and the tv looked like it was in the poltergeist movie. Honestly I'm surprised more devices didn't fry.
That is quite the story. Lost neutrals can definitely be dangerous.
If the neutral on main board were so well grounded with a structural ground on building structure, the chances of damages would be so reduced, I've had a lost neutral too, if my neutral weren't grounded, would be bye bye to my microwave oven and my frost free refrigerator at once.. but fortunately, I did my neutral grounded, it's a *TN-S* system! 😅
I always kinda knew why the high/low voltages were happening but this explanation really solidified my knowledge of why. Thanks so much for the video!
Thanks for the feedback. I’m glad it was helpful.
thanks for the reply. At 2:10 you said they were phases or legs. That’s two different things. Either way you look at it, it’s a single phase transformer. What we really mean when we mention phasing is time. Are the two legs out of time with one another? No they are not. There is nothing that can cause a delay. So they are in time. An oscilloscope would show a 120 volt sin wave or a 240 volt sin wave with their peaks being at 170 volts or 340 volts. The two legs do not add together to create 240 but rather we are breaking the 240 in half with the center tap. By doing so we are only changing the amplitude of the sin wave. All measurements are relative with respect to reference.
My phone always gives an error when replying to a comment so I have to leave another comment.
Excellent comment!
Single phase , each leg to neutral 120v. 240 across both legs.
@@Randall-mt7jkcorrect. One sin wave has twice the amplitude as the other and that’s the ONLY difference between the two voltages. They are the same phase.
Good points. Note that loads which only require 240 volts (e.g. electric heater) do not need a neutral, though they should be grounded.
@@aspensulphateso the 3rd (round) prong on a 220 volt plug, is it a neutral or ground?
Friend bought an old house, old 2 wire no ground romex. Some later wiring added with ground. Got shocked in bathroom, even though had working GFI outlet. It tested okay, but everything supposed to be grounded, was HOT, intermittently. Overhead fixture, device frames, cover screws, etc.
After looking around, what was rewired, added over the years. The bathroom had been rewired with floating ground wire not connected back to panel. Along with added ceiling fans in nearby living room. A single tiny strand of hot wire on fan was sticking out of wire nut, touching floating ground wire. Creating intermittent shock hazard whenever fan switched on. Fixing that fault, running ground wire to panel, that problem was repaired.
Hard to tell what hazards lurk in walls and attics. Even if things seem to be working.
Wow! What a story. That definitely was a dangerous situation. Sounds like a hard thing to track down.
The best explanation i have ever received. Thank you for sharing your knowledge!
Thanks so much for watching and for the feedback.
Thank you for taking the time and effort to produce this excellent tutorial!
You’re welcome. I appreciate you watching, and I appreciate the feedback
This is an excellent explanation. You were absolutely correct except at 6:01. It should have been, "instead of turning left". Otherwise, it was perfect.
A lot of confusion, conflict, and controversy exist, however, because some folks don't have a proper understanding of the term phase and the different meanings it can have. When you say that the 2 ends of the transformer, or legs, are 180° out of phase with each other, that's correct. They are. That doesn't mean that there are 2 phases in the circuit. A 2-phase circuit doesn't exist. But there are some people who believe they do. There are only single-phase circuits, with the two legs 180° out of sync/phase with each other, and 3-phase circuits. You could build a generator and circuit with more than 3 phases, but there'd be no advantage to it, and it would cost more for the transmission lines.
Good job!
Excellent explanation/demonstration. Congrats and thank you.
Thank you
Just had FPL out and this was exactly my issue with dim lights with microwave, table saw etc. I always thought it was me replacing with smart switches, omitting 3-way red wire etc. thank you so much for giving me the kick to finally call them out instead of wasting hundreds on an electrician.
I appreciate your feedback. I’m so glad the video was helpful.
Problem fixed! You Sir are a blessing! Much appreciated!
Thank you for the time and effort you put into this demostration, it's very well done and I learned something new today!
You are very welcome.
great demo. thanks!
You’re welcome
Excellent, excellent demonstration.
Thank you
Just had another issue with the neutral line going to the transformer on the pole. I had some strange power fluctuations again but not as drastic. So I put my clamp meter on one leg going into my panel. Then I turned every other breaker off putting a larger load on one leg. It showed a voltage delta of about 15 volts. I called FPL and they sent a service truck out. He pulled the meter and put a device on it to check and it showed it was just over the allowed difference. After inspecting the ground cable he saw where my neighbors tree was chafing the wire. It was warn down to a single strand. They replaced the neutral drop and it is now fixed.
Good thing you caught that and followed through on it. I really appreciate you sharing that. I and my viewers learn from everybody else’s experiences.
Absolutely makes sense. Awesome.
Thank you
Great video. Can you speak to the dangers of having a bonded neutral on your generator versus it being a floating neutral when using it to power your house through a manual interlock? Thanks!
Excellent, precise explanation. Thank you.
You’re welcome!
I worked as a cable tech for 16 years. I also worked in a beach area where the grid was copper but all there service lines were aluminum. The two different metals would cause the neutral to fail fairly often. Very dangerous, if you were not careful. Low volt guys get little to no training on this. Most of the time the connection point at the bond would completely melted and that was a dead give away. But sometimes it wouldn't be and if you didn't hit it with your FVD you would get sparks flying when the wrench touched the coax fittings.
Ouch, that’s terrifying.
Very interesting. Thanks for watching, and thanks for your comment. Yes, these lost neutrals can be very dangerous.
Excellent explanation and demonstration.
Thank you
This is a wonderful explanation & video!
Thank you!
I think I finally understand this. Thank you.
I’m glad it was helpful.
My brother had this happen at his house when a lady hit the power pole across the street and he also had a bad ground at the breaker panel which caused the whole house to try and back feed through the 14 gauge ground wires on the furnace and dish washer as one was connected to a gas line and the other a copper water line into galvanized iron water line. Needless to say, I am glad that his daughter skipped school that day as she quickly went back and turned off the main after seeing smoke start rolling out of everywhere. I had to go up and replace all the wiring on both appliances and ended up installing a new ground rod outside along with bonding it to the gas and water lines.
Wow! That’s scary. Good thing the daughter knew to turn off the power. These situations can definitely be dangerous.
A hint, if your house isn't made of wood, use your iron structure as earthing grid, it's an awesome earthing, and saved me of appliances losses, I'd lose my microwave oven and my frost free refrigerator if my neutral weren't so well grounded on building's steel structure, look for structural earthing, my system is a TN-S.
Thank you so much for posting this video! We had a big wind storm roll through yesterday and knocked out the neutral wire to our home. I wasn't sure why our lights were acting strange; but now I know. Thank you!
I am glad the video was helpful. Thanks for watching and thanks for the feedback.
Thanks for the good demonstration.This will help other save themself. Can be a very dangerous situation. I have seen this happen a few times. One has to learn this before one plays with it. The fist thing he taught me was to respect it and treat like it is HOT!
I was 12 years old Back in the 60's and I was wiring houses with my father. {unknown to me at the time. When he was in the USN he was a an EM and also was an electrical instructor. I wounder way he had all those books around that I read.) As a teenager I joined the USN and was an Electricians Mate and advanced right to C school. and Aced it was not much to right home about. Skipped A school all together. Any navy guy knows what that is. later in life acquired a BS Electrical Engineering. Build power plants and switch yards and control yards. Sorry about ringing my own bell. May next do 3 and 4 way switches. I just shake my head at times when it's not understood by someone that call's themself and electrician.
So true. Thank you for your service. I too am former navy. Nuclear propulsion officer on the submarine USS Florida back in the early 90’s. Learned a lot about electricity doing that.
Depends on how you ground your neutral wire, if you don't have an wood house and use your steel structure as earthing grid, and earth your neutral properly to your structure (I did my connection welding, so no bad contact never), your neutral never gonna become a HOT wire, I did my system as a TN-S and it saved my appliances from the lost neutral on public electric grid, I'd lose my microwave oven and my frost free freezer if my neutral wire weren't so well grounded, and guess what? My kind of earthing creates a Faraday's cage, never gives a shock inside my building perimeter, even if happen a direct short circuit on structure, I tested, it's like the phase's potential vanishes on ground.
Nice demonstration. Thank you for sharing your knowledge.
My pleasure!
Thanks for the great video. Well thought out. Well demonstrated.
Thanks so much for watching and for the feedback.
Lost neutral situation can happen also on 240volt circuits or anything sharing the neutral like 12/3 circuits
Wow Tgis video is super educational and solid information. Tgis is great to know. And recommend it to be tougt to anyone wanting to get into the electrical trade. I appreciate it.💪😎
Thanks so much for the positive feedback. I sure appreciate you watching and commenting.
@ no problem 😌
I’ve had that happen at my house during a hurricane. A tree fell on the drop to the house separating the neutral. As soon as the lights went bright I knew what happened and ran to secure the breaker. It took out the refrigerator, microwave, oven, dishwasher and clothes dryer. Completely fried three surge protecting power strips and burned out a bunch of light bulbs.
Yes, it can be very destructive to electronic equipment. Good thing you knew enough to recognize what was happening and shut off the power as quickly as possible.
Damaged the dryer? Wow. They use 240V usually, but some use 120 also to run some circuits, if that side goes high it could do damage. If it goes low, not so likely.
@@franklofarojr.2969 It fried the circuit board. I replaced it with an old 1980s dryer that has been refurbished. No electronics works better than any new dryer I have had.
Back in the day when a washing machine had a more mechanical clock timer for cycling.
I already had a Neutral lost, but luckily, I've previously grounded my neutral mains cable to the house's iron structure, doing an structural TN-S earthing system, so even with a lost neutral, the internal cable that was neutral didn't gave any electrical shock, even during a test with all appliances out the outlets and purposely shorting one live leg to the grounded wire, the phase wasn't able to give any shock while connect to the structure, I was like the potential had vanished to the ground, I know it's actually the Faraday's cage effect inside the building, only a perimeter circulating grounding like the case of using the steel structure can do this effect, but about the appliances, I had an air conditioner working on about 120v on one leg, and a microwave and two refrigerators on other leg, but the microwave was on standby, the current on kitchen was lower, so if my neutral wire weren't so very well grounded, I'd lose my microwave and my electronic controlled frost free freezer.
It's so important *ground the neutral wire* very well, this can save you during neutral losses or even when a high voltage wire hits the neutral on road.
Not only that. As the neutral is bonded to the ground wire the voltage on the neutral gets to any grounded equipment case. This could in worst case kill. Here the instruction is to get out and call the power company and not to return until it is fixed but we have higher voltage.
You are correct. Thank you for clarifying that.
I don't know about US but in Czech (EU) you have to have 3 wire system and connecting neutral to ground is forbidden. Yes there still might be old houses to have it but in own interests should rewire it asap. Also every house have to have "ground protector" which measure current leak from main to ground and Tripp in matter of milliseconds.
@@VavrMar You mean the ground wire? That is known as TT. It is used in many countries in Europe. Others use TN-C-S where the ground wire connects to the neutral at the entry. Such a system does not require RCDs to work though they now are mandatory as additional protection.
@@VavrMar It's because one ground rod never gonna be enough to ground the neutral and still be safe even on a neutral loss, the only kind of earthing that remains secure even with a neutral loss is the *structural* one, the kind that use your building's steel structure, and have to be a so well performed connection, welding, this kind of earthing creates a *Faraday's cage* and is the only secure option to use *TN-S* system, my installation earthing is TN-S and is secure, I had a neutral loss but nothing on my house gave any shock, because more important that just grounding, is equalizing, and my structure is literally a *Faraday's cage* and I didn't had any accident, and it even saved my microwave oven and my frost free freezer of having their electronic circuit boards fried!
Thanks for the reminder.
You are welcome.
maybe this is a better way to explain and understand. If you remember ELI the ICE man we know that a reactive load causes voltage and current to be out of phase with respect to one another by some amount of angle. That is to say they are out of time with each other. Voltage happens first or current happens first. This is because a capacitive circuit delays the voltage and an inductive circuit delays the current.
With 3 phase, the 120* angle between each phase comes from the power company with their generators being 120* out of sync with each other.
In the case of a single phase transformer secondary, this is not a load but rather a voltage source. There is nothing in it that would cause a delay in time.
I did watch your video and your meat and potatoes of what you’re explaining is spot on. It’s just that when things are taught with misunderstandings, it causes confusion to set in and the confusion gets taught to the next group and so on.
When I studied in the 90s I went above and beyond what was taught in the classrooms and I missed a lot of test questions because of it. One that I remember was marking a question false that said current can only flow in one direction through a diode. I knew how a voltage regulator works by flowing current through the diode backwards so I marked it false. My teacher had no clue what a zenor was. I’m an hvac contractor now and work with electricity every day but I’m not an electrician. Sometimes I wish I’d learned that trade instead.
Whatever you are, you sound like you really know your stuff. I was guessing you were an electrical engineer. I honestly have always heard and believed, and therefore thought that the two 120 V legs were 180 degrees out of phase. I learned that because of one being wound clockwise and the other being wound counterclockwise that they are 180° out of phase, and that makes total sense to me. You have gotten me to thinking, and I am going to do some more research, and get ahold of an oscilloscope. I will probably make a new video based on this discussion and what I learn. I hope to talk to you more.
Excellent demonstration. Thank you for sharing.👍🏽
Thanks for watching, and thanks for the feedback.
I had a bad neutral at the transformer. The symptoms were a voltage difference between the phases. I showed the lineman the voltage differences, but he didn't seem to believe me. Took the bucket up to the transformer and shook the neutral. A shower of sparks confirmed the diagnosis. They replaced the transformer.
Great story! Thanks for sharing
Thanks Mike. I’ve done heat and air most of my career and started my own business 5 years ago. I’m near Memphis. I struggled with this very concept but the guys at our local power company are the reason I understand it now. I’ve been up there several times early in the morning when they get there to start their day and pick their brains. There are still concepts I don’t understand so I’m always learning. For example, nowadays they are teaching that voltage is not a force and I’m really struggling with that one because that was the entire basis of electricity when I studied in college back in the 90s. Electromotive force = voltage.
I really struggle with computers. I don’t have the patience nor do I understand all the errors I get. With an electrical circuit, a switch energizes a load. When you apply voltage to that load, current WILL flow and the circuit WILL work. Sort of like pressing a key on a mechanical typewriter. You press the key and the hammer WILL hit the paper. With a computer, you give it an input and a thousand things have to happen before the computer decides to energize the load. Or you press a key and the computer receives a request, thinks about it, and decides if it wants to respond. I hate computers and right now I’m frustrated because I’ve tried again for about an hour to figure out how to respond to these comments and I get an http status error 400 error when I reply. Nothing on TH-cam or Google has worked. I’m using an iPhone 15 pro max that is 3 months old.
But yeah I’d love to see you do a video on this. I’ve done a couple videos myself but I don’t know how to use the computer to do the animations and stuff and I don’t know how to edit a video so mine are just one take and they were just on capacitors proving that current can flow through them. Experimental stuff. I’ll subscribe so I can catch it.
Well, I have an engineering degree, but I’ve been a home inspector for the last 22 years. I love learning and I love teaching. I have learned that I love making animations and I’m trying to make better and better videos. I’m getting older and spend almost all of my free time working on new videos because right now it is my passion. I often have to learn things before I make my videos so I can sound like I know what I’m talking about. You have inspired me to continue on. It’s been good talking to you.
I understand your misunderstanding.
I have generally been in the automotive
field and know that a hot & a ground makes 12 volts. Hence, an electrical component works. Occasionally, the addition of a resistor or relay change that basic Hot/Ground logic. No problem , I'm still on board.
Then came the computers. I throw my hands up and say, nope, ain't gonna try to understand.
Well , then I dabble a little and get a tiny understanding.
Don't trust my logic on this, and I gladly stand corrected if I'm totally off base.
Your observation of flipping a computer switch and it simply sends a signal is correct , IMO.
In my world (automotive) , the revelation came to me from watching a college student explaining their "Robotics" class. The student went into Can Bus theory. Can Bus ? (maybe I've spelled it wrong) , where have I heard that before ?
Yep , in newfangled automotive electronics diagnosis.
Can Bus - High.
Can Bus -Low.
From my understanding, the Can Bus system runs on 5 volts or less. The Can Bus system goes through a system of checks of this, and that before energizing the desired component.
All sensors sending signals ?
Seat belt fastened ?
You get the picture .
From what I understand, Can Bus High generally operates critical components.
Ignition, fuel supply , Etc.
Can Bus Low generally operates secondary components.
Seat belts , heated seats , radio,Etc.
Going back to the Robotics class theory.
A robot, theoretically, cannot move its right leg until it receives a signal that it has already moved its left leg in a walking scenario.
Cars are now robots.
The car will not start (hypothetically) until it receives a signal that the seat belt has been fastened.
Thank you. Great video.
Thank you
Got called out on a washing machine having problems finishing the cycle. When i got there i turned it on and the laundry room light got super bright. The washer motor was overheating from low voltage. Neutral was broken at the main entrance.
Thanks for sharing your experience with a lost neutral! It's a great example of how dangerous these issues can be.
Excellent video!
Learned something today! Thanks! How would a panel mounted surge protection device affect this situation?
I can’t imagine that it would change anything. Surge protectors are designed to shunt very high voltages. 240 or 250 V would not even be detected by a surge protector, I don’t believe.
awesome video, great explanation
Thank you!
A really great video, Bravo!
Thank you
Took my electric company sending 6 guys out over months to figure out they had never tightened my neutral in my meter panel. Whole time they blamed me. Took a new guy to find it and replace it.
Wow! Glad they finally found it. Sometimes those lost neutrals can be difficult to track down.
Excellent video Man, I learned a lot. Much appreciated.
You have a new subscriber.
Thanks so much!
Wow that's scary I never thought about that. Very well explained thank you.
You're very welcome
I think that problem only happens in countries using 120 volts because they have three cables going to their house from the transformer (+120v, 0v, -120v). In countries using 240 volts that's not a problem because they only have two cables going to their house from the transformer. If they lose one of the cables the light won't turn on.
Yes, you are correct. It only happens in countries where the voltage is split at the transformer, so countries that only use 220 or 240 V do not encounter this same problem.
@@morganinspectionservices3840This sort of thing does happen in countries using 240V systems, because the distribution is 3-phase. Factories, apartment blocks and other large premises get a 3-phase supply (that is supposed to be 415V between any two phases and 240V between any phase and neutral) and most houses get one of the three phases, rotating from house to house along the road. Loss of the neutral causes different voltages on the different phases according to the loads on them, and you can get things burning out because of excessive voltage.
Few countries use 240 V. Most of Europe is 400 V three phase and the same thing can happen. With 240 V there is another problem. Remember the neutral and ground are connected. What is in the neutral will be on the equipment cases. In single phase 240 V that is full 240 V. Now one can avoid this by not connecting the neutral and the ground and relying on RCDs.
In the UK EV charging points need to be protected against the broken neutral or PEN-fault as it is called there. This can be done by using a ground rod for ground. As it is RCD protected it will be safe. There are also more sophisticated methods.
We had this on a 3 phase 240 V European system. Something was blown at the transformer and the lights were dim. We had a heavily loaded phase with the dishwasher turned on where everything survived and two almost unloaded phases where many power supplies were blown. Since most switching mode power supplies can operate on 240 V without issues it's not a huge issue in the US nowadays, but here in Europe we get over 400 V which blows most of the power supplies. Luckily if it's manufactured correctly the high voltage will make a component short to the earth (and sometimes a capacitor will also blow up), protecting the electronics behind so only the power supply needs to be replaced.
@@okaro6595 In all the US service panels I have seen, it is impossible to separate the neutral from the ground, electrically, unless you insulated the neutral bus bar from the panel, and I would think that would be a code violation. I was wondering as I watched this if the building ground wouldn't mask a lost neutral, as the neutral is also grounded at the pole. Granted, many if not most buildings have inadequate grounding, but I would think that in a properly grounded system it would be impossible for a lost neutral to cut all current flow on the neutral on the building side of the system.
One thing that I didn't see really mentioned, though no real good electrician would run into this problem, is that the "neutral" of the right side of the circuit will now be positive with respect to ground. So if you think you can touch or work on that neutral and be safe, you better think again
Very true. I do think I mentioned somewhere that there can be voltage on the neutral. I did recently release a new lost neutral video. It specifically covers and even measures the voltage on the neutral.
Call the power company as the problem is their neutral.
If you call a electrician you will be stuck for service call $ , and they don't work on power company lines.. This could be over $100 for a minimum call
The power company will service and fix the neutral connection.no charge.
These electrical neutral problem s are dangerous and eerie.
Our aluminum framed screen porch was measuring 40 to 70 volts. My dog yipped as she went outside because the aluminum frame and door was electrified.
I put my fluke black lead into the nearby ground (soil) and the red lead on some aluminum - ac voltages were all over the place. I think the electricity found a ground but also found a ground that energized the aluminum frame which was also grounded. 😮😮
Good point. Thank you.
There's an issue with your grounding system, on my house, my steel structure is the grounding grid, if I short one phase to it, the phase potential vanishes on earth (Faraday's cage effect) and I can even touch the grounded phase wire with my bare hands during the test, so my ground grid is secure to do a TN-S system and it's what I did, on day I've lost my neutral, my ground and neutral wire on my internal installation didn't got electrified, I could touch the appliances metal cases without getting shocked due the*Faraday's cage effect* what prove structural earthing is secure, but also has to be done properly, and this is what I done, my connection to structure is welded, never gonna be lost.
Interesting video...I'm in the UK and often wondered how you guys managed to have both 120v and 240v in the house. Out of curiosity, if a customer has a lost neutral, could it be detected by plugging in a simple GFCI tester in the outlets? Also, do you guys have a separate ground/earth/CPC wire in your electrical ccts?
Nice video. Power company came out today and ran a temporary neutral to my meter and they will bury wires in a few weeks. Have had flickering lights for some time.
Thanks. Glad that you discovered that you had a problem before it got any worse.
Interesting. Here in UK the consideration is typically diverted neutrals because of subtle differences in the way you & we feed supply current. In the UK case it's where neutral currents end up flowing in the ground/earth/protection wiring (as most distributions have repeated connections to Earth).
does this prevent or mitigate the issue or is the issue just happening differently? i sound stupid i know but apart from being able to wire a plug i am an electrical idiot.
@@mysterycrumble In the US system you have two live or 'hot' feeds which are anti-phase (opposite polarity) so that you can have ~240V power hungry devices connected between them.
When you 'lose the neutral' then you have your two sets of 120v loads connected in series, so 240V, without the neutral stabilising the 'mid point' voltage at zero (the two hots being +120 and -120v relatively speaking). At this stage the weaker side of the two hots tends to 'blow' from having over voltage, and hence on that spur, over current.
Meanwhile back in UK we have far more domestic circuits distributed from local substations where the neutral and earth are connected for multiple household supplies (often US supplies being a local transformer so only one or two with the common neutral/earth at the supply pole). so..
Now with our older infrastructure we have more cases where the supply cable has lost the neutral ("broken PEN") and instead the local 'earth' conductor is doing the work of the return path. And that return path (i.e. the whole supply current for other properties & services that neutral also fed) can prefer to run through your household earth wiring, especially if you have rock solid earth bonding, earth rods, copper water piping etc.
An example could be the (faulty) street lighting that is seeking to return via your household wiring which isn't sized to carry such currents. Also makes for EV charger risks (an outside power point nearer the street light than the house) requiring extra detection for spurious earth voltages and sneak current paths and multi-way isolation).
Everything is great when it works as designed. We're just getting better at being concerned about real world faults!
Back in the 1970s, at a railway locomotive shed owned by a railway preservation society in Britain, an idiot decided to turn off the yard lights by removing the neutral link on the lighting fuseboard (3-phase 415V supply), with the result that there was an immediate cascade of blown lamps.
I agree with the term idiot. That’s crazy. And that’ll certainly do it.
Thank you excellent information delivered 👏
You’re welcome
Good information thank you .
You’re welcome
EXCELLENT object lesson. I'd be curious to know what would happen if a UPS (Uninterruptable Power Supply) were wired in place of one of those light bulbs, and that lightbulb was plugged into the UPS.
If each lightbulb had its own UPS, would they be protected from burning out?
The UPS would likely protect the lightbulbs from burning out because once it detected the voltage fluctuation, it should either shut down the power to each individual lightbulb, or switch over to battery power, depending on how it is designed to operate.
The current flow at 3:45 is backward for a balanced load with no neutral current. The diagram shows the neutral current as additive when it should be subtractive.
I had to go back and watch the video. I’m not following you because I am showing balanced loads on the two legs and then no current flowing on the neutral so I am showing it as subtractive. Please explain a little more and we can discuss this.
A few years back went on a service call where the homeowner had smoked up a flat-screen, DVR, and stereo system after a 1500 watt electric fireplace had been running for about an hour. It was a lost neutral on a MWBC feeding the master bed & living room with backstab connected receptacles. A backstab connection upstream burned out on the neutral. Home was built sometime in the 1970s if memory serves me right. This expensive ordeal would have been avoided had the receptacles been installed in accordance with 300.13 (B) which states the neutral of a MWBC cannot be interrupted by removing a wiring device.
Great info/example. Thanks.
Thankfully, I live in Chicago, where everything (almost) is in conduit, and MWBCs are not as common, especially in older buildings.
I do run into hack jobs where someone had scabbed in an illegal 14 or 12/3 'BX' and either ran both legs on a tandem or 2 separate breakers where the handles were not tied together. The Chicago NEC upped the allowable length for 'BX' to 25' from 6' (whips) for 'enclosed/protected' spaces. I expect to see more problems popping up as people (either DIY or remodeling cos.) run new circuits without the knowledge of how to do it properly and/or use 'backstabbing' on devices.
MWBC = Multi-Wire Branch Circuit
I got these symptoms but no electrician was able to diagnose. I had to change many cables hoping the problem went away, and yes, at the end it was a broken cable coming from the street. The more you know
It's amazing how one wire can make such a big difference.
This is so important. Thank you for causing a bit of fear and interest in abnormal electrical workings. I remodel and occasionally wonder why strange things happen. Thank you.
Thanks for watching. I appreciate the comment.
Am I correct that if you turned off the third light on leg 1 that all the lights on leg 2 will turn off due to being an open circuit?
Yes, that is correct.
Excelent! Thanks for sharing
You’re welcome. Thanks for watching.
Great animation!!
Thank you, great information. Neutral for dummies.
Thanks for watching!
Nice job Mike!!!
Thank you
Is there no ground on the transmission lines?
No. There’s only the hots and the neutral on the transmission lines.
An open or high resistance neutral conn in the panel or meter can will also cause this. Not always upstream. I've been on many trouble calls where the nipple between the two was glowing because of a loose neutral in the panel. Some were never actually tightened by the original installing electrician.
Great info. I guess when I said upstream of the panel, I actually intended prior to any of the branch circuits, so yes the neutral lug on the panel would certainly qualify. Thanks for the clarification.
@@morganinspectionservices3840 You are correct though. Probably 90 percent of my trouble calls were due to homeowners allowing trees to grow up into the service wire and either breaking the neutral, or rubbing it in two midspan on the drop. People don't understand that the power company isn't responsible for their negligence.
This is a good video, but how does this work with grounding? Isn't the neutral bonded to ground at the panel? How would that affect your diagram and your demo circuit?
Hi. Thanks so much for watching and thanks for the question. Grounding really does not affect this because the Earth has such a high resistance that you will have a small amount of current flowing down the grounding electrode conductor to the ground rod, but it will be very minimal and will have almost no effect on what I am showing.
However, all of the ground wires running from the receptacles and lights back to the panel will not be at 0 V. They will be at a voltage that is determined by calculating the difference between the voltages on the two legs and dividing that by two. So let’s say you have 180 V on one leg and 40 V on the other leg. You’ll have 70 V on all the ground wires in the home. This obviously makes a lost neutral, extremely dangerous. I re did this video several months ago to include this. Here is a link to that video.
th-cam.com/video/YY5Fur7S-KE/w-d-xo.htmlsi=8XB2134lleqX_Yb7
@morganinspectionservices3840 Thank you for the explanation and the excellent videos!
Now can I ask an electrical engineer a question. It has always seemed to me that AC voltages of 120 or even substantially lower are very easy to get shocked from, but DC current don't seem to be this way at these voltages. What I am asking is this, is messing around with batteries that are 90 volts or 130 volts a dangerous shock hazard? Landline telephones operate at 60 volts DC power. Antique 20's era radios had battery banks that operated up to 135 volts. I have been powering old radios like this by putting together 9v batteries in series to about 90 volts but have always been a little leery about the safety of handling such things. I have carefully tested lower DC voltages on the back of one hand and couldn't seemingly feel any current. I have somewhat assumed that 60volt DC may not be quite as dangerous for the simple fact that phone wiring is pretty wide open in the public sphere. Could someone clarify this. I have looked quite a bit online a few times to try and find some discussion of this.
I will start off by saying that both AC and DC voltage can be dangerous and fatal, however, the human body seems to tolerate DC voltage better. One study I read says that the human body can withstand approximately five times the DC voltage than it can AC voltage. If this is correct, then it would take approximately 600 V DC to give the equivalent shock that 120 V AC gives. AC voltage, which is alternating current, seems to affect the body more than direct current does. Alternating current has a greater tendency to cause atrial fibrillation than DC voltage does. The human body seems to have a higher impedance (resistance) to direct current than it does to alternating current. Having said this, every body is different, and low DC voltages can sometimes be fatal to some people.
When I was building electric cars 35 years ago, I got shocked by a 72V DC battery pack. Not bad, but shocking. It's about as bad as getting hit with az24V AC (thermostat or sprinkler valve). I can feel 42V DC as well.
I was taught it takes approx 40v before you feel anything, having said that, the current is what hurts you so it depends on the power supply. For example, static electricity is thousands of volts but is very low current so you feel a “pin prick” at worse. The North American public telephone system was around 40v DC (?), it gave you a bit of a buz under the right conditions enough to feel it but no kill you (depended on individual circumstances, humidity and skin resistance). The path the current takes in the body is most important too. If in doubt and you must touch the wires, I was taught to use the right hand thumb and index finger or just one finger, the idea there is that the loop urgent would be localized and not travel through the body across the chest through the heart down to the legs into the ground. Current needs a path through you to another conductor, usually ground in most cases of shock. Having said all this, the safe way is to not touch wires above 30v (I was taught that) and gamble with fate, there’s enough testers out there to safely indicate live wires.
Generally voltages below 50 V AC and 120 V DC are safe in case of an accidental exposure. The primary safety method is always to avoid the exposure. Laptops operate at 19.5 volts because 20 V has been considered the limit below it is safe.
If you operate with 90-130 V treat it like it was mains voltage like have no exposed contacts.
Happened at my friend's house a couple yrs ago,strange things started happening to lights etc.wind caused limb to break the neutral at the pole
@@jimmybaker4610 yes, It definitely create some crazy symptoms - especially if you don’t know what it is.
@morganinspectionservices3840 we tripped main service first thing.didnt take long for power co. to locate problem.
Worst case scenario from a floating neutral at the service drop could be electrocution from energized water pipes and metal case appliances with 3 prong plugs, because until I believe the 1978 NEC, a cold water pipe could serve as the sole grounding electrode if at least 10 feet was in contact with the earth, and the connection to the grounding electrode conductor is made within 5 feet where it enters the building, and plastic pipe could have been used to replace a section of corroded metal pipe. Because the neutral and ground are bonded at the main service panel, a double loss of ground and neutral could have lethal consequences. To combat this, a water pipe used as a grounding electrode must be supplemented by grounding electrodes in contact with 8 feet of earth with a resistance not to exceed 25 ohms.
Thanks for the info. I really appreciate it.
Water pipes still are bonded and that is for safety. In case of broken neutral you do not want 120 volts between your stove and the water tap. It is safer to raise the potential of the water pipe.
Thanks for video. I have a follow up question. Does bonded grounding and Neutral at service panel help to mitigate serious consequences laid out?
No. When your service loses a neutral, nothing done at the panel that I can think of will change the fact that you will have the two legs in series on a 240-volt service.
How do you test for loss of neutral?
If neutral is still bonded to ground, the ground can serve as a return path to the transformer, though it's not an efficient path due to earth's high impedance.
Great video, I have been having problems, I had the electric company come out they said on their side it good, so I bought a multimeter and sure everything is good until I turn on the microwave on certain days some days the microwave doesn't change anything and other days it makes the fan speed up so I go to the meter pole and leg L-1 is 132 and L-2 is 117 so is the problem on me or electric company and could the bad neutral come from half a mile away i don't share a transformer i live way out in the mountains.
You definitely have a lost neutral. However, the symptoms are the same whether it’s on your side or the power company side, so it is impossible to say where the problem is originating. It’s just going to take some investigation. I will tell you this that you would not be the first person I have heard of the power company saying that it’s not their problem and then later discovers that it is.
And the reason that you have the problem on some days and not on other days, depends on the load distribution of what is currently running in your home. If you have a heavy load running such as air conditioning,clothes dryer, or things like that, then turning on the microwave will have a much smaller effect on the voltage than it will when very few things are running.
I wish I could help you more, but long distance troubleshooting is very difficult. If you can give me any more information, I will help you as much as possible. I would definitely be interested in hearing what you find.
@@morganinspectionservices3840 Thank You so much, and I will give the update of the cure if I ever find it, today I turned everything I could find to bring one leg down, but it would only drop 2 points, the kitchen is on leg 2 so I had hot plates refrigerated, space heater , L 1 at the meter pole showed 120 L-2 showed 124 nothing was running on L-1 but in a few days seems it is usually a hot day it will actually up again. I can measure the house or at the meter pole it's always the same, I was told if the legs are unbalanced at the pole it would be the electric company problem.
I have both legs hooked up again in order to find the problem.
How does the ground affect this? The neutral and ground are bonded at the panel.
You will have some current flowing from the panel into the earth due to the groundingelectrode conductor. Since the earth has a high level of resistance, there will not be a lot of current flow, but probably a few amps.
@@morganinspectionservices3840 Thanks for your answer and this great video. But I'm still a bit confused. What then is the purpose of connecting the panel neutral bus bar to a local ground rod?
@@hueywallop2461 ---- the neutral busbar shouldn't be connected to the ground rod. The neutral busbar should be connected to the neutral from the meter. The ground wire comes from the ground rod and either cold water pipe before the shut off valve(residential) or building steel (commercial) and up into the service panel hitting a ground hub on the connector used for the ground entrance into the panel then to a ground busbar or to a ground lug attached to the panel box with a nut and bolt or a hole that has been tapped with threads for a screw to tighten into.
For demonstration purposes this is an okay way to explain it, but this is the reason that the NEC doesn’t like you to share neutral wires anymore for a long time now. The 240v circuits would single phase but that should trip the breaker because of unbalanced loads to protect them, this is also the reason that you are supposed to balance your panel loads. This explains better what happens when you lose your neutral from the power company, but not really what happens to individual circuits in your home, but it’s a good simplification of the situation.
Yes, it was only a demonstration to show what happens when you lose your neutral from the utility company. But yes, I guess it also demonstrates why shared neutrals are not a good idea.
Great demonstration! Is there a monitoring unit that you can install on your load centre that would cut power the instant neutral was lost, for example due to a fallen branch in a storm or perhaps an ice storm?
Thanks for the feedback. I am not aware of anything that monitors for this. I will have to do some research.
@morganinspectionservices3840 I envision that it would be simple. Perhaps monitoring neutral to ground in a strategic location outside that would pass a small current and when that current stops, you could have a lost neutral condition.
Which country are you talking about? What type of installation?
This is the type of system used in the US.
@@morganinspectionservices3840 Problems of that kind are very dependent on country and distribution system, so it is context one needs to know before voewing a video like this.
The three (3) bulbs on either leg are wired in parallel.
(Although the two (2) legs are now in series to each other with the lost neutral.)
When one bulb is turned off, the Resistance goes up and the Current
goes down (in that leg) because they are in parallel.
Naturally the leg with the highest resistance (series circuit) has the highest voltage drop.
"When one bulb is turned off, the Resistance goes up and the Current
goes down (in that leg) " - i understand that resistance goes up if we swich off 1 light in the circuit because its parallel so it is as if we closed 1 of the 3 roads for the current - so more resistance. More resistance means less current in that leg but both legs are in series so the current is the same. So if the same current is flowing while the voltage is much higher means that a lot more energy is on the side when 1 light is off. Does it make sense the way i rephrased it?
8:48 damn i really need to go back to school, but why is the resistance higher with 2 lights compared to 3? Isn't light burning cause it has a resistance so if you remove 1 of those resistances how is there more resistance all of a sudden ?
With three lights on you have three equal paths for the current to flow. With only two lights on, you only have two of those paths for current to flow. The more paths, the lower the resistance.
I had a shared neutral on 6 plugs in my garage. A wire nut failed and I had a lost neutral in my house but just on 4 plugs. It destroyed a charger before I noticed the problem.
If a neutral becomes disconnected inside the home, then that’s actually a different situation than what this “lost neutral“ video discusses. We typically call your situation an open or disconnected neutral. I have a separate video on that. Sounds like you were already able to solve the problem. However, if you need it, here is a link.
th-cam.com/video/BVcNnBKfC8Q/w-d-xo.htmlsi=7Gb7tGew_n87GCKy Temperature
@morganinspectionservices3840
That video did a good job describing a lost neural on a 120v circuit. I’m referring to a shared neural. Which acts more like this video. So imagine this.
You install a 240v circuit breaker. Then you take a 14-3 from the circuit breaker box to an electrical box with 2 receptacles in it. So going into that box you have red, leg1; black, leg2; white, which is a neutral shared between the black and red; then green, your ground.
Red goes to a 120v plug on the right. Black goes to 120v plug on the left. Both plugs have a pigtail going to the single shared white wire.
Now disconnect that white wire inside the electrical panel. Plug a lightbulb into both 120v sockets. The energy follows this path.
Black wire
Light bulb
White pig tail
Second white pigtail going to the other plug
Second lightbulb
Red wire
So you have 240v going through 2 120v lightbulbs. Being protected by a single 240v breaker.
Now you have your demonstration but inside a house. Fun fun watching things smoke. 😁
Would a whole house surge protector help at all with preventing this?
No. A surge protector will not help at all with this condition.
what is the impact on the consumer meter reading if in a three pages meter, neutral wire is directly connected from supply to the wire of consumer i.e input neutral is not connected to the meter input and neutral output of meter is not connected to the consumer neutral wire? Pls note the three phases are still connected via the consumer meter.
Hi!
Hope i didnt miss anything in the video, but what would happen in this situation if the electrical supply ground was lost but your neutrals and grounds were (obviously tied somewhere) tied in the panel and you had a good ground rod out side (obviously tied to your ground, and neutral bar if they were tied together)? would the rod them act as your neutral and help alleviate the situation of a lacking neutral? And if it did, would it affect grounding safety through your house? thanks!
The ground rod would not act as the neutral because it does not tie back to the transformer. Some amount of current would flow through the grounding electrode conductor, through the ground rod, and into the ground. However, the earth is a very poor conductor, so the amount of current flowing would be limited. I would estimate 4 or 5 amps only. As a result, the voltage difference between the two legs would be lowered to a degree, but not by a lot.
@ Thanks for the reply! Cool stuff
Interesting, I'm surprised it doesn't just go to ground since nuetral is typically grounded at the panel if neutral is broken upstream of the house.
A small amount of the current does go to ground, but the earth is a good insulator, so the current is fairly low. I cannot say how much, but I would guess that less than 5 A will go to ground.
Great demo. Scary too. Is there not a way to detect that ? Or protect ? Specially if lost neutral can be an external event.
Thank you. I don’t know of any way to detect it other than noticing lights dimming or brightening, or other things running faster or slower than normal.
Can you do a video about a floating neutral as opposed to a lost neutral?
Sure. I will put that on my list to do soon.
@@morganinspectionservices3840 thanks so much. Can I ask you a different question q: so in this guys video here ….is he talking about a “lost neutral” or a “floating neutral” ? He calls his video “floating neutral” but after watching it I realized…..he is talking about “lost neutral” right? And why is his system diff from yours? His has 3 homes connected to the secondary but in America we only do one? So 3 phase means 3 homes and 1 phase means one home ?
m.th-cam.com/video/b9hDHGxaufM/w-d-xo.html&pp=ygUQRmxvYXRpbmcgbmV1dHJhbA%3D%3D
Thanks for the video. I tested the plugs of my home and I found that a few plugs have 50v between neutral and ground (220v power supply) , may I ask why the voltage is not zero between neutral and ground lines?
Are the outlets where you’re getting the 50 V close together where they could all be on the same circuit? If so, it’s likely that there is a bad neutral connection somewhere so you’re getting some resistance on the neutral wire. As current flows through the neutral wire, you will get a voltage drop, which will put some voltage on one side of the neutral.
@@morganinspectionservices3840 Thank you. I guess they are in the same circuit. Btw, would that be a hazard if it is a bad neutral connection that I should be concerned?
@@erihsehc2 It certainly can be a hazard, but it’s not definitely a hazard. It just depends on exactly what’s going on. Loose connections can result in arcing which creates heat which can result in a fire. It also puts voltage on neutral wires switch can, under certain conditions, cause somebody to get shocked. If you’ve done any electrical work and feel comfortable, you could check the affected receptacles to see if there’s a loose connection there, or it could also be in the electric panel where the wire is connected to the bus bar. Best thing to do would be to call an electrician.
Partial 'lost neutral' can be caused by having an inadequate ground, such as a grounding rod that is too short and in a rocky base (such as your grounding rod going into dry limestone).. also, this is why fueled gensets have a neutral grounding post..
The lost neutral and poor grounding should have nothing to do with each other. In fact, there’s a lot of older houses still around without a ground rod. Typically the ground lack of a ground rod doesn’t cause a problem - unless there’s a voltage spike or some transient voltage on the powerlines.
It's called an 'Open Neutral'. And yes, it's the most important connection in any system that has a Neutral. Always identify and connect the neutrals first when doing any kind of switching,controls,loads to minimize problems. If you make a mistake the circuit/logic may not perform correctly but at least if the neutals for the loads are connected the chance of a dead short or a shock are greatly reduced. The neutral is the most important connection.
Thanks for watching and for the comment.
Is this an issue you have to only worry about in North America or if you have a 3 phase supply?
usa is 3 phase
How would you get a lost neutral condition? Don't these circuits typically have independent neutrals back to the breaker? Also I thought the neutrals and grounds are bonded at the breaker panel.
A lost neutral occurs before the breaker panel. As a video explains, a lost neutral can occur anywhere between the transformer and the breaker panel. Maybe the neutral gets corroded or pulls loose at the weatherhead. Maybe a tree rubs on it, and overtime breaks it. There is also a situation called an open neutral, and that’s something that affects an individual circuit or a portion of a circuit. That is a very different situation.
This happened to me and it smoked every 120v transformer and motor in my house, including the hvac blower. What a pain that was. Even the refrigerator fan, and it took me a few months to even realize that one.
Wow! Another example of just how much damage this situation can cause. Thanks for watching, and thanks for your input.
Even worse in my opinion is when this fault occurs and the return current finds its way back through the equipment bonding conductor tied to utilities, e.g. catv. Imagine the grounded shield on catv carrying back dozens or more amps. Whole home bonding junctions are a good thing but this is what can happen more easily now.
Yes, that is definitely a dangerous situation.