Why Neutrals and Grounds are Separated in a Sub Panel
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Here we go over the reasons behind why neutral and ground wires are separated in sub panels. I also simulate what happens if you leave the neutrals and grounds bonded with a bonding screw or strap and where the current goes within the grounding system in a bonded neutral scenario.
I learned years ago that electricity doesn't just flow in the path of least resistance, it flows in every path available with the majority going to the path of least resistance.
You can really think of electrons in the conductor like a nearly incompressible fluid in pipes. Flow is established via propagation of pressure waves back and forth until equilibrium is reached - on non conducting paths, equilibrium just means static voltage/pressure rather than flow along a voltage/pressure gradient.
I suppose bonding the EGC to the Neutral conductor on Sub-panels would force MCB's to erratically not break the circuit spontaneously in case of overloads ?
Certainly current loops would cause data corruption on data lines between devices present on different sub-panels.
I am a Factory certified York, Trane, Carrier, (list goes on) Chiller Technician, and Factory Freq Drive Tech. HVAC, Controls Tech. 25+ years. I just wanted to say to you, that you are very knowledgeable, and make some excellent training videos. I point my apprentices here quite often. Great Job!!!
How much do you enjoy being a factory rep as compared to working for a privately owned HVAC contractor? Thanks.
@@bradvincet1848 For me, There was good and bad. The smaller shops don't have a lot of the support but working for the Factory, there is way more corporate bullshit you have to deal with. It all depends on what you can tolerate. When I worked for York, it sucked completely. Corporate would take all of our profits from our office division, and then peddle back pennies for our tools etc... Siemens was the same way. I work for the largest privately owned contractor on the west coast, now, a Union Shop, and we have almost 100 HVAC techs in Service.
I'm turning 57, and my body can't take a lot of the knees and carrying around 28ft extension ladders. I do straight piping construction install now. Working at Microsoft building their new 80 acre campus in Redmond wa Thumbs up!!! No more oncall!!!
I spent years working on electric controls for cranes and conveyors but never had any reason to work on service entrance panels or sub panels. You did a great job of explaining why the neutral and ground need to be separated in the sub panel. I really appreciate your teaching skill.
I did a lot of industrial controls work when I was a EE engineering co-op and transitioned into the software side. This was in the early 80's and our dainty little circuit boards had to live with 3ph motors, etc. This was in the early 80s, and a lot of the heavy stuff was not as sophisticated as they are now. Man, talk about EMF, current, etc.
Purdue had a lab in the basement full of motors, caps, coils, and big wires we had to connect up various scenarios for dealing with startup and phase shift andetc. All 440 3ph. Just the potential (pun intended) for disaster forced one to think, re-think, check, re-check many times before throwing the switch.
Plain and simple to the point. This makes it easy to explain to homeowners. Great video.
THANKS!
Great Job!! I am a licensed electrical contactor (in NC) with my Unlimited License and you have explained "Why Neutrals and Grounds are Separated in a Sub Panel" very accurately. Thanks for the time and knowledge you have shared with others!
I still dont understand why you connect them in the main panel .... ?? in Europe people NEVER connect neutral and ground in any panel .. not the sub panels not the main panels .. ever ....
@@ZILAwelds What.. what are you talking about? Yes we do?
We've had electrical service for over a century. If it took them until 2008 to put the kibosh on this, it can't be THAT great a safety risk, can it?
@@ZILAwelds u guys dont have lightning in europe?
@@bcubed72 Your observation is correct. This has been in the NEC for well over 50 years.
You did a great job explaining this. I’m 36 years into this trade and this was one of the better explanations I’ve listened to.
Agree Have 36+ myself and THIS explanation IS the best by far
4Biz surfing around TH-cam I’ve seen so many guys giving how to videos on various wiring methods and Installations that have no business teaching anyone. It makes me sick. Unfortunately someone’s going to follow their advice and get someone killed or burn someone’s house down. There’s been a couple things his done on some of his other videos that sort of made me cringe a little and I think man if I could just show him a few things it would really help him and he’d really excel
Damn shame 36yrs in trade calling yourself an electrician, and your taking tips from this amateur.
Dre Day where did I say I was taking tips. I heard this try to be explained by so many “electricians and trade teachers and even engineers” and all I said was this was one of the better explanations I heard given. You need to read what I wrote a little closer. I said I’d love to be able to show him a few things. Besides that I am always learning new things, you have to in todays world because things change so rapidly. I don’t use methods today I used 30 years ago. If you think you know everything and are unwilling to adapt your not much of a electrician. Although Maybe your one of those people that know everything.
@@scottg444 I like to get other opinions,too. I'm 30+years in the trade,but I'm rewiring my 132 yr old house and I'm not a residential guy. Industrial control work and commercial are completely different. Im not a know it all who wired the sun. As a side note,another electrician could tell an ind/comm guy did this work by looking at the EMT piping for my porch ceiling fans and lights. My wife loves it. Lol.
Awesome video. Suggestion: To identify the possible source(s) of leakage to ground, turn off all breakers, monitor the current on your sub panel ground conductor, and turn on one breaker at a time. Note which breakers cause current to be present on the ground wire.
process of elimination right
There is some bonding on the furnace if you are getting a reading on a gas line. Look for a ground clamp inside the furnace service panel that installed by the installer.
I am a retired electricl engineer that worked for a power company for 36 years. If you have current on the gas pipe it is VERY dangerous. . Case grouns connect the case of stove, clothes washers, refrigerators so that if you touch one appliance and another and the hot leg/ground is reversed you get a bit of a shock. A case ground/neutral should never be connected to the actual ground. That current showing at the gas pipe could cause damage and gas leak through the pipe and than a fire. Don't fool around if you are at all nervous about working with electricity. I would recommend a licensed electrician.....many "electricians" ARE NOT licensed and while they may be OK....they could also make a mistake. Should you have a fire the insurance company would most likely check if wiring was incorrect and if it was the homeowner that did the work...THEY could be SOL.
When i see TH-cam videos trying to show how to do something like his it scares the hell out of me. There is a good reason why cities require work like this to be inspected after done. There are also issues with balancing the load across both circuits but I won't get into that.
@@RobertKarlBerta I do electrical work and find plenty of licensed electricians who miss half this stuff. Its about education and support to pay for the needed work to be done correctly. Ive followed these guys around for a full day troubleshooting a job and they never solved the issue and the next day I located the problem myself and corrected it. And you cant believe the BS song and dance Ive heard from licensed professionals which I know is totally false in order to charge for repairing "broken wires" in the walls. And Ive paid top-dollar electrical contractors and had them leave me with an "Open Ground" which messed up the voltage, creating about 90 volts house-current, after the inspector checked the work as ok. And I called the inspectors back and they called for corrections ASAP. (I wont name any names, but they're well known in my home town) You cant depend on a certification, it simply gives you leverage on the need to correct bad work.
@@RobertKarlBerta just because one is licensed or not, means little, people with no training can be very very clever and pick up stuff quickly, they can read and absorb stuff and apply it to practice, licensed house electricians know zilch, they are unemployable in industry, mining, aviation and ships engine rooms and reticulation, I do all my own stuff, switching in star/delta etc, I wire the vessels i build but get it signed off by a licensed person
sure you are correct about the furnace, this guy just put up a good vid, give him some praise
The weird current you're getting can also be from your stove or dryer not having the neutral/ground separated out when they made them 4 wire. There is a bonding jumper added to both dryers and ranges for 3 wire configurations that use to be allowed.
Stoves for sure
I didn’t think of that. I am going to check this in my house now.
This just smells like "ah, more work for a licensed electrician to charge for and fix". 😁 (Run a new feed that has four wires so ground is properly done.)
My issues was my hot water tank, and I never found it till one time we lost one leg of power to the shop and a few lights on the down leg glowed slightly and I turned off the hw breaker and it quit. Now any phantom loads I always start turning off 220 breakers til it quits...
The bonding jumper is usually pre installed on the equipment so if the installer doesn’t know that they need to take it off then RIP
yup, absolutely, I work in HVAC and I had a service call once at an old farm house in Kane Co Illinois here. I went to pull the panels off their old furnace in basement, kneeling on the damp concrete floor and got nailed. I got nailed about 3 times before I realized the furnace and gas line was electrified with about 90 volts. I touched the panel of the furnace with one lead of my Fluke and touched the concrete and got 90 volts. After some investigating I found the grounding rod strap was broken off the grounding rod by lawnmower and the panel still had the bonding strap installed. So, I learned about all this the hard way and sometimes, that is the best way to learn them because you;ll never forget.
Same thing happened to me (well similar thing). My last rental house, had a chrome pedestal fan in the shed. After a few days rain, in bare feet, went to move the fan and almost latched onto it. Measured from the neutral to a steel rod on the concrete and got 140v. On further inspection, it turned out whoever had replaced the feed from the house to the shed had only run twin. No earth at all.
@@jimmyb1451 lol, no Earth ground at all. That'll do it.
@@johnnyb8629 well.... in this case, yes.
There are times when a floating supply is far safer than an earthed one.
But yes, given that it's grid power... no earth'll do it every time.
You mean a sub-panel still had the bonding strap installed, right? Because there is no bonding strap in a furnace. Also, they must not have had two grounding rods pounded in. Redundancy is important for something like this. And another thing, I bet the rust on the bottom of the furnace made it insulated, because if you got a shock, then it had to be electrically isolated.
@@katemoon7476 It was the strap that connects the grounding rod to the panel broken off by lawn mower or something, and yes they still had the ground buss connected to neutral buss. everything was electrified, the furnace chassis , the gas pipe, was 90 vac from chassis to concrete floor.
I worked for the Gas company for 35 years. A fellow employee and close friend was changing a gas meter on the side of the house. He was on his knees as he attempted to stand up due to limited room on the side yard. He put his hand on the fence and the other hand on the meter set assembly to get up and was electrocuted and fell unconscious.
The house was feeding electricity back through the gas line. As a result employees now use a low voltage tester to test the meter set assembly before working on the gas meter. The employee after several years regained use of his arms after severe nerve damage.
Thank you for this video, very educational.
I always wondered how people get shocked when touching a grounded piece of metal. Was it perhaps a very dry sandy climate? Otherwise it seems like the electricity would normally take the path of less resistance, and a metal pipe being buried for miles under ground would seem the natural path.
Or Can the gas co. use plastic or other insulating materials as pipes or junction points? Maybe they do this to protect themselves?
Appreciate your thoughts and insight.
@@Rick-the-Swift
The employee completed the ground by touching the hot house line and current went through his body to the chain link fence.
The employee had removed the gas meter prior to touching the fence.
On all gas meters sets an insulating bushing or Union is installed if the gas service is steel.. Over the last 40 years or so only plastic service and mains are installed.
The incident occurred due to improper house wiring. Just an example if wiring is not done correctly.
Thank you for your input, I hope this explanation helps.
By the way, the employee was nick named
“SPARKY” and was called Sparky for many years after.
That makes sense that the gas pipe was insulated while the metal fence wasn't. Regarding the bad wiring, I've encountered times when grounds were "borrowed" for neutrals because I'm guessing whoever wired it that way likely didn't have the proper amount of wires when installing or didn't want to fish for a neutral. Combine that with the fact that many people have their panels grounded to a gas or water pipe and I could see the potential for these things to happen. Thanks for helping to make me feel a bit smarter.
I love a good anecdote!
@@jessehooper8491 this guy sparky channel right now?
It's amazing how often I used to have to correct neutral-ground connections on sub-panel submissions from major vendors. Good vid.
First & foremost, thank you. I have been in the electrical industry since 1978. Master electrician since 1990. This is clear and well explained as it relates to isolating these conductors. Secondly, the load center is tied in nicely. A true craftsman. Not sure who tied it in, but coffee is on me. Stay safe!
Great video. I also worked as an electrician during my career (now retired) and knew some of this but didn't realize there were so many other paths for the electrons to find their way back to ground. Proves that we never stop learning.
If you're retired, the reason you have to keep learning is because of CRS. I learn the same thing 4-5 times per week according to my great grandchildren.
It's crazy how life works.. 3months ago (11 months into my apprenticeship) I did not understand a word this guy was saying.. I would just watch something else.. now?! I understand so much more! I always come back and I learn something new.
You said something important here , namely online learning is valuable. I agree fully.
Great video, great job explaining why to separate and what happens if they aren’t totally separate. Not sure what you have for other utilities in the house, but I have seen where you also get amperage on the neutral and ground from phone and cable aswell. About 10 years ago all the utilities started bonding everything together so if the electric company has an issue like a bad insulator for example it will bleed into phone and cable aswell and in some cases onto customer grounds depending on if customer ground is better than their system and cause issues. I have had to install neutral isolation boxes at some houses due to amperage on the ground about 4 amps even when power is completely shut off to the house all coming in on the cable.
Love the way you simplify and break things down making complex concepts easier to understand.
Best explanation I've seen of this. I did a lot of googling and read a lot of useless information on this before it finally made sense, and you just explained it in a completely logical way in a matter of minutes. Great stuff! Subscribed
As an older electrician, a lot of this is a great refresher and some is stuff I never knew. I am not 100% in the electrical field because I ventured over into the HVAC&R career
Thank-you so much! After watching your video, I realized that I never removed the neutral crossbar in a sub panel that I installed in my basement (next to the main service panel). I removed it, and the grounds and neutrals are now separated. It 'looked' correct with all the grounds installed on one side and the neutrals installed on the other, but both bars were tied together with the crossbar!
Good job! Note; there can also be leakage to ground finding a path through appliances or any connected equipment, i.e. the appliance grounding is doing it's job.
This is the best explanation I heard. You did it with examples when they are connected and when they are not. Thank you!
As a fellow Minnesotan, I really appreciate the information you share! Keep the great videos coming!!!
I really appreciate videos like this. I am not an electrician but I do work on my home from time to time (including working on installing solar right now) and I really love to learn as much as possible. The fact it was passing to ground via the gas line .. freaks me out a bit.
no need there is no risk. i have disconnected a gas line and lit it up with my torch it wont combust it just puffs and puts itself out. gas is only a danger when it is allowed to fill an empty space slowly from the ground up like a basement. the gas is more dense than oxygen so it immediately falls to the ground in an enclosed area. if you ever open your basement door and smell gas there is a very good chance the entire basement is full of gas. my 0.02$
Great video. I have never seen a practical explanation so well illustrated. Many dryers or cooking units come equipped with a bonding jumper from the neutral to the ground for use with older electrical systems that didn't bring a neutral to the receptacle. The NEC allows for this in article 250.140 Exception. Many times you will find this bonding jumper not removed as it should be for newer installations which then bonds the neutral and equipment ground.
Ben I am a master electrician and wanted to say your demonstration was spot on and is an excellent teaching tool to show the importance of bonding and always trying to handle your loads. In Maryland we use to bond to gas pipes and had to install ground jumpers across unions on gas pipes . I subscribed to your site and will be checking your videos out. Keep up the good work !
But why say power and not current.
I’m 2 years into my own apprenticeship 🥺 also MD :o
Never ground to a gas line. gaslines are plastic! The black pipe is only 2.5 feet long.
@@robertkattner1997 If I understand right it is propane; metal but still very short and should be wrapped where it is contact with the soil.
It is a natural gas pipe line underground 3 feet, yellow plastic. Comes up to the meter with black steel pipe covered with polyurethane. No ground contact. BC Canada. Groundrods are steel rods electroplated
with a thick copper layer.
Wow, finally on TH-cam I can watch a video by someone that knows what they are talking about! Good job and explanation!
Great tutorials for those who do not know much about electrical circuts. Added a new GFCI circuit to an outside shed, when I powered up the breaker it tripped. I immediately knew I had a problem, well, not anymore. Thanks for sharing your knowledge with the world. Subscribed to your channel and look forward to viewing more of your videos.
I knew that the neutrals and grounds needed to be separated in a sub panel but could never figure out why. Your explanation was great!! Thank you for putting out this video!!
Learned a lot from this. I was an electrician's helper for a couple of years, but I never really got an explanation on the loads for panels and balancing since it was pre designed I just followed the blue print. Now it makes a lot of sense, thanks.
You did not get an explanation probably because of the person training you did not understand the theory.
@@Lost1inDetroit Most of the companies I went to we were basically cable pullers. The journeyman that got me in to electrical taught me basics of 3 phase, length, gauge, and doing a legal install. But, theory was not taught to us low level workers since we were considered labor. I was pretty excited just to learn conduit bending from journeymen when they were up to it. Then went about the time I started apprenticeship school the recession hit and the company folded. Hell we had a lot of temp guys that didn't even own a drill.
You really nailed it. This video could be part of an electrical training curriculum. Great work
Thanks for this video, I have explained this many times but your delivery makes it much easier to follow. Not just claiming the path of least resistance. Thanks .👍
A couple of years later, still really good stuff. Thanks, Benjamin.
I really appreciate someone who has gained enough knowledge and experience that they are able to explain concepts to people in a clear manner. That is a skill not many people have, even in their supposed area of expertise. I congratulate you. And thank you. I am learning a lot from you, even in my old age.
It helps to understand the reasons for the requirements of the NEC. (Bot: "NEC" is the acronym for National Electrical Code.)
I also appreciate it when someone can explain ideas clearly. I agree not many people have that skill. And I don't think Benjamin Sahlstrom has that skill. He is not always choosing his words carefully, and sometimes he ends up saying something that could be interpreted more than one way, he says something ambiguous and therefore I don't know which of the 2 or more possible meanings is the correct meaning. He does this quite freqently.
Loved the explanation! Good job :) My sister is adding on a bathroom to a guest house and will be doing some electrical work so I am back watching this again as a refresher. You're the man Ben! 💪💪💪
I’m pretty sure you don’t need more ground rods at your sub panel.
Maybe a little more on why the scenario you explained is dangerous,
@@dennisbielinski3611 Voltage on the furnace, gas line or whatever is looking for a path to ground. It doesn't care if that path happens to go through your heart.
Since grounding is grounded (aka 0 volts) it carrying a current. Lets say for some reason he had to disconnect his gas line. Now there is potential (aka voltage between to separate pieces). Which contacted together can gas a spark.
2. Suppose the he cut himself working with that seperate pipe. He could get shocked if rest of him is well gounded. (Your skin is somewhat insulator until voltage overcomes it. But your blood has a much lower breakdown voltage).
So is the equip ground bar in the sub completely isolated from the metal sub box? If a sub is right next to main and connected to main with a metal conduit wouldn’t the sub effectively be part of the main box?
I been doing electrical wiring for years ( Elevator electrician) your review and code applications is excellent, easy to follow and understand, keep up the videos
Hey great video great explanation. I've 33yrs experience as electrician and am a c10 electrical contractor in California since 2000. Again great explanation. This is something most electricians fail to grasp... and I use a a test question during employment interviews. I'd like to hear you explain more on this but explain the path of fault current in a branch circuit from the sub panel , with the binding jumper installed at sub
Im SO glad you reconsidered your idea to disconnect your neutral wire.
If you disconnect the large neutral wire as you know, you'll send all the neutral return current through the jumper. Now at the moment you did this test, you didn't have a great many loads running in the house - only about 15-16A, but because you turned off every other breaker, you caused a pretty unbalanced load between the two hots. If more and larger loads happen to come on, you could easily see 40, 60, or more amps on that jumper wire and of course it doesn't have overcurrent protection either. Well, at least you'd be there to respond to the melting jumper wire.
Whoah. Sounds really dangerous. You know that warning sticker...DO NOT PLAY ON OR AROUND its for kids. You need 1 on your breaker box!
Or how 'bout KEEP CLOSED
This is essentially the ongoing argument...
3 wire 220 stove vs
4 wire 220 stove. Grounded chassis or not..
btw Some 220 v. Pool Equipment won't work with Neutral shorted to Ground. Best they're kept separate. Ground is for grounding the electrical chasi. Only. I do understand you're looking for leakage. Trying for safety. I'd unplug 1 appliance at a time until I find them. Vampire draw.. parasitic draw..
Motion sensors... TV actively searching (watching) for remote control signal to power up, well that consumes power!
Thank you 4 food 4 thought!
An unbalanced load without a neutral can destroy all your lamps and appliances.
I’ve been watching a video a night for the past week. This one has probably been my favorite as it explains what is happening to current flow and not to mention something every electrician ought to understand! The wiring diagram brought it all together for me. I’m a first year wireman apprentice and watching your videos have been helpful to my education. Keep em comin!
Cool video man. I had an apprentice ask me about this the other day, I could see it in my head, but the words escaped me. I'm glad you went above and beyond and actually tested the gas line.
Appreciate the actual visual aspect of your videos. It actually clicked when watching this vid and was always trying to understand bonding. Big thanks and much respect. 👍
Benjamin, very well done explanation. I've spent 30 years onbaord Army ships and familiar with home and shipboard circuits. Looking forward to more of your discoveries.
It is one thing to know, and another to be able to communicate that knowledge. Thanks
Great video! This also applies to RVs.. You will pop a GFCI breaker in the supply panel if your neutral and ground are connected. Kept me quite busy as technical crew on a large horseshow! Very glad to have found your channel. Best to you~
In your panel the two black "hot" conductors are passing over the ground wires coming from the various outlets in the home. Although they are insulated, the AC current in the hot conductors generates a changing magnetic field which will induce a small current in the ground wires. This follows the same principle as to how your Clamp Amp Meter is able to measure current flow. Other devices in your home that draw lots of power could be doing something similar (ie. inducing current on the ground wire).
Exactly.
The reason that in the main panel the neutral and the ground wire are connected together is that if the neutral wire becomes disconnected (e.g.falling tree limb) then the main panel may end up with unbalanced voltages (e.g. 160 volts across 1 hot leg and 80 volts (240-160) across the other hot leg. This means that by separating the neutral and the ground at the sub panel then the same 🎉disasterous situation could occur if the neutral to the sub panel is disconnected for any reason.
To add, the possibility of a neutral break in the line between the main an sub panels would be unlikely since the wire is enclosed in pipe. The falling tree limb scenario would not happen with this neutral line
@@crellis2000 Why would this cause an unbalanced voltage? Also, would the return current now be returning through the grounding electrodes?
@@SteveSmith-nh6ms sorry Steve, I didn’t answer the second part of your question. Yes, if both the neutral and the grounding wire are connected, and the neutral wire is broken, i.e. falling tree limb, then the ground will provide the route back.
Ben do a visual inspection of insulators or isolators on your neutral bus bars. You can also pull the cooper wires away from your sub panel to test the insulators.
From a master electrician best explanation and proof why to separate that I've seen my local inspector didn't know this! You sir have done a great job with this video!
Inspectors are only failed contractors or someone who could not make it in the real world contracting...they do not know shit unless they can find it in a book or conjure it in their their little shit heads....Virginia...I do not know about other localities.
Thanks! This was great. There's nothing like good data to help solidify an understanding of the practical difference between a Safety Ground and a Circuit Neutral. Bravo!
4th year apprentice here. This is the best explanation I've seen on this topic thus far. We should play this video at my trade school. Well done.
great vid, watching in quarantine. We have a house energy monitor already (Efergy, it works ok) or I would buy the sense right away. Everybody reading, support Benjamin and buy a sense with his link. It's very cool to see when you turn on the heat, microwave, lights to see the power usage for the house. It helps you track down silly power losses and do things like upgrade to LEDs for frequently used lights and think about how power is used in your house. In our house we have a heating system that uses electric resistance heat (! so expensive) when the thermostat is more than 2 degree difference from target, so we learned to only bump up thermostat 1 degree at a time to prioritize heat pump use which is 3-4 times as efficient.
Very good explanation. I installed a subpanel on my house years ago, I followed instructions and did it correctly for the exact reasons you describe. In fact all should be aware of any situation that could have return current on ground line(s). You used the word "power" interchangeably with current. The potential (voltage) will always be there, but you won't have power without current in a circuit. Thanks and subscribed!
It is interesting how many sub-panels have been installed years ago and WORK on the old standard but no one goes around checking them and requiring the changes.
I went over to a friend's house and he has a sub-panel that a break was broken, worn out ...
So I pulled the old one out replaced it and saw that that panel the GREEN and WHITE were bonded to the same ground bar.
I might need to make a visit to change that someday.
Also, his Dryer and Ranger use a 3 prong heavy amp plug that the NEC has not sent him a notice to update from several years ago when it was originally installed.
Could be other items as the house was built in the '40s and updated as needed over the years.
I should add that in the early 80s his insurance company paid for these LICENSED electricians (he check the licenses they had) to change his 2 slot outlets to 3 prong ones, I checked recently, and not one of those outlets are grounded. The original order charged the insurance to ADD a ground wire at each electrical box, not one of them was grounded. Explains why anything 3 prong with a circuit protection circuit shows a wire failure.
The Electricians did ground the 3rd prong to the Neutral wire.
Now he wants me to come in and rewire his home, not sure if I want that task, I do Low Voltage, but anything I do is better than what an ELECTRICIAN did.
There is a load somewhere in the system that connects its ground and its neutral. I would check the leaking current while switching each individual breaker off until identifying all ground and neutral connections.
Could be induction as well. I see they followed the 90 degree rule on all those grounds (after the 90 up is a little close to that second leg) we see in the video but, I would have routed them the long way around to avoid this. Just my 2 cents.
Maybe he has a 3 wire range or dryer in his house. Not sure if that is why but I'm just speculating.
Dimmers and electronics sometimes leak a small amount to ground. Or possibly some leakage on the coax ground.
@@philliphensley7748 LED lights, UGH I have to connect the Ground Neutral then HOT to keep from getting a buzz to the hand.
Surprisingly when I connect the neutral after the ground many times I see an arc.
So not sure those Chinese are following NEC and UL specs all that closely.
MADE IN CHINA is the new warning label.
Likely it is inducted.
I do a lot of 'side-work' on really old homes in Chicago. Everytime I open a main panel, it's a rats nest of wire - ground wires everywhere, whites hooked up to breakers, blacks to neutral bus, and green, red, blue wherever.
I so appreciate seeing a panel that looks like the one you are working on here. I get a little choked up at the beauty.
Nice neat load center wiring !!!!!!
When we install home generators, the hardest part is usually separating the grounded conductors and the equipment grounds in the main load center. The new transfer switch becomes the first means of disconnect, therefore requiring this. Also the we have to move the electrode grounding system to the new transfer switch.
You've answered something I've wondered about for 20 years. Thanks!
Good video! I'm a fellow HVAC/R skilled tradesman. I saw on your "About" page that you've ventured into the plumbing and electrical trades as well. That makes sense, since the HVAC/R trade requires that we know both of those trades as well.
Truly excellent! Well done. This was as clear as an instructional video from the Home Inspector coursework. Superb work. You have a natural talent.
Great Job, I commend you for having the Guts to try and explain why the ground, and grounding conductors are not bonded together in the sub panel, but are grounded in the main panel.
One of the branch circuit neutral conductor is grounded at the load. Start with the electric oven, dryer, air cond. Great video
You did a very thorough job explaining why the neutral and ground are separated in sub panels. Thanks!!
Very precise and accurate explanation. Great job. I have seen far too many incorrectly wired sub-panels during my career.
Thank you for demonstrating a concept that Nobody could explain to me.
I think it's because he assumes nothing and does this as if the person is intelligent but has never done this before and he lays it all out so nicely with details that others just forget to add for the layman that doesn't know that little tidbit of information the normal worker doesn't think twice about but is essential for true understanding of the topic. I personally knew 3 phase at the outlet wiring and thought the neutral was another word for ground but now like youself know what that wire does. What amazes me is the gas line does not explode with electricity running on the copper since copper is conductive I'd think the gas would just explode but that was an incorrect assumption on my part but that scares the hell out of me gas and current together just makes my old fashioned mind twitch with anxiety of gas explosion without warning.
@@shawnh8498
Yes. I have never gone to school for it, but I have been wiring for 40 some years. I knew not to do it,but never knew exactly why. I guess the demonstration clicked in my head.
And yes, I agree that gas and electricity don't go together!
Right sir
@@shawnh8498 An explosion is a chemical action. That action requires a fuel, oxygen, and an ignitor - all present together. For an explosion to occur, the fuel (gas) must be in the presence of oxygen and a heat source (like a spark) to cause the fuel and the oxygen to combine.
Great video!
Regarding the source of the current in the ground line mentioned at 12:55. Power line line filters like those used on computers have a capacitor from hot line to ground. This may account for what you measure. Cheers
You earned a like and a subscriber; thank you. I could never get an explanaton as to why neutral and ground wires were in the same bus and you made it make sense.
I subscribed because of how amazing you did at explaining this.
No one else has been able to explain this well enough for me to understand the full concept. Thanks for putting in the effort man, seriously.
Great job with the explanation. Very simple to understand. Now you just need to find your leakage problem. It would be nice to see how you work through that diagnosis.
@Benjamin this is a great video, I work in the Cable TV industry and run up against similar issues to this where there is current flow on the customers cable lines since it is bonded at the pole to the verticle, as the coax we use is not rated for current it tends to melt the coax and also cause peoples modems and cable boxes to lose sync with the network. When I turn this over to have an electrician correct this 9 out of 10 have no idea where to start trouble shooting this type of issue. Many is the time where the customers neutral becomes broken or disconnected and the Cable line to the home starts acting as a path to ground for the home.
As a sparky from Australia, thank you. Clear, concise and relevent.
Also your leakage could be from what ever has an element... Kettles, hot water systems and even [old] toasters.
Ben: You asked why you still had some current leakage on your EGC without the bonding jumper connected between the neutral and the EGC in the subpanel. There are two scenarios where this will take place. The first and most likely scenario is there is some current leakage in the connected load served by your subpanel; dimmers, pilot lights, surge protectors, transformers and old worn lamp holders are the usual suspects (could be in the control voltage of your furnace). The good news is the current wants to travel back to the source, and installing a dielectric union on that gas connection will make the ground wire of the supply circuit to the furnace a higher potential than the gas line. The second least likely scenario is that there could be a potential difference between the grounding electrode system of your main panel and that of your subpanel, and you could have some neutral current from your main panel finding its way to the GES of the subpanel. By the way, your video is the best explanation for the existence of Article 250.24 (A)(5) that I have seen so far. Good job!
That was nice thanks for the explanation. I was thinking cheap China wifi switches 😂
Hello, So that I understand. Your saying that the Dielectric union will fix that low current leak because it isolates at the union? Thanks for the explanation. I initially figured that may be the issue but not sure
@@MichaelDillin I think it is BigClive that has a video of a european USB charger that has a USB shield connected to hot (220VAC!!!) through poor design and careless construction!
Serious knowledge there!
This is why for jobs more complex than installing a light or outlet I just pay the electrician.
Thank you so much. After watching like 10 videos of how to troubleshoot a water heater. Yours is the only one that actually thoroughly explained everything enough for me to fix the water heater myself. God bless you sir
That's great!
I finally understand. That’s scary how much stray current could be flowing back through equipment grounds. Thank you for this explanation.
Some of the old Dryers and Ranges had a bonding jumper in them for the 3 to 4 wire change in plugs back in the 90's
Best explanation I’ve watched to date! Getting ready to do a 125 amp Sub Panel using the same style box and this answered a couple of my questions! Great Job!
Thank you Benjamin for presenting information in a clear easy to understand exciting manor. Much appreciated.
What a great video not only explaining , but showing ground loop current. Your sound is crisp and clear and your videos are well lit and in focus. Your video editing is well placed, like when you measure the current, then show the value you have stored on your meter. I have watched this video several times showing my friends why you don't bond the neutral to ground in their garages and sheds. I have but one correction for you and it is minor and does not detract from your video. You refer to current as power as in "1.5 amps of power" throughout the video, but power is a product of voltage and current. You did mention that current flows to ground which is correct. All in all I give this video my two thumbs up.
The reason you are still getting current (albeit much less current) flowing through every single pathway to ground is because current is flowing from your main panel (which IS tied to neutral) through every single possible parallel pathway to any ground source. So some current is back flowing from the main panel ground/neutral back to the subpanel ground wires to anything that is connected to the earth (chassis, copper pipes, etc.). Electricity takes ALL available paths. Remember, even paths of relatively high resistance that are in parallel with other paths of low resistance will pass current. Think of it like a big water tank sitting on a hill. Sure, most of the water will flow through the biggest pipes, but even a pin hole will allow droplets to weep out too.
Excellent explanation.
@@BenjaminSahlstrom Thank you for your kind words. Electricity is a fascinating force, and I don't think we realize how little we really know about it.
So, you can disconnect to ground back to Main panel outside and measure your neutral to see if the 2.2A is added to your remaining grounded (neutral) measurement.
If you have bonding as you said then there is a path from all of your earth grounds to the earth ground at the power pole which is connected to the neutral of the transformer. That path is in parallel with the neutral wire from the pole to the house and can take some of its current. If you don't have bonding anywhere in your house system then there is still a tiny current because of high resistance leakage and even more by capacitance inside of equipment. I once connected a transformer to the line and measured 80 volts from the secondary to ground using a VOM. You can determine the presence of AC by feel if you are grounded (a high resistance ground is safer) and you lightly rub your hand against a live metal surface (it is safer if the metal is painted). The feeling is a buzz which is present only while your hand is moving and it is caused by the electrostatic attraction that is present with the voltage. This is called a poor man's voltmeter.
Your response makes sense and alludes to other potential sources: Induced electricity, such as can occur when current passes through one wire and the other wire picks up a charge when the two wires are close together, spinning motors or other means. When I am teaching basic electrical system theory I use the water pipe theory. Black is your water supply line, the sink is the equipment where work is done, white wire, like PVC pipe is your drain or return/neutral line and the ground wire is the bucket you put under the drain in case it leaks. The ground is never intended to be a primary source of drainage. That in general helps most people visualize residential energy flow. I explain that bonding is a type of grounding that connects various systems to the ground. So, to your point, if it was your intention, is that current in ground systems can flow both from the panel or to the panel. I have a suspicion that the energy flow could very well be flowing into the panel and out the ground and or neutral and could be independent of the energy that originated from the panel (think as a drastic case, lightening strike). The sources of electricity could be multiple, hard to track down and possibly impossible to completely eliminate. That is why the system is there, to allow for a method to drain this induced electricity that some equipment can store up a charge as a capacitor would. The bonding and grounding systems provides a low resistance pathway. That said, to the best of one's ability, those stray sources should be identified and eliminated where possible.
Great explanation that brings to bear why on yachts (or any boat with shore power) the neutral conductor floats on the electrical panel, NEVER jump the nuetral and grounding conductor together on a boat. This happens back on shore at the source.
We test for potential on boats because the water around the boat can be energized with AC current....FATAL mistake if you fall into the water.
When we find low current such as you find on the gas line we shut off all breakers and energize one at a time until we find potential. When we find voltage to ground we turn off or isolate items in that circuit until the leak stops.
A number of times it is an appliance or piece of equipment that has a ground fault of some type will be discovered.
Energized grounding conductor will then create electrolysis with interaction of dissimilar metals underwater the water becomes an electrolyte to carry current potential between the disimilar metals. Boats have sunk, metal appendages have wasted away and has proven fatal to swimmers as a result.
This can cause electrolysis with neighboring boats as they share the common grounding conductor through the power pedestal on the dock.
My boat has an isolation transformer to disconnect me from the potential stray current from other boats while grounding my system.
Marine electrical systems are specialized systems with potential to mortally
Well stated Tom!
Excellent Video!!! I like the OPEN Neutral example at the end. Which is one of the main reasons why we do not tie the sub-panel neutral to ground there.
Great information...thank you! I posted a photo of the inside of my electrical box for a bit of humor, as the wires weren't neat at all and it's probably as old as the house (1970's). Someone pointed out that my grounds and neutrals are all on the same 2 bars at the top of the panel. Of course, they suggested I have an electrician look at it but I'm really not thrilled about having the wires all reworked or possibly getting a new box. Your video helped me to see that there could be a real danger to leaving it as it is, so I will have it looked at. Passed inspection 6 years ago though, so I don't know what changed...unless they never looked in the box!! Thanks again!!
Yet, it might be a cheaper route to go, buying a new box, than to have someone injured or killed because of 1/2 assed wiring solutions, …
What a nicely organized pannel!
I'm glad you're teaching people. They need to learn this stuff. I used to do rough ins in Columbus Ohio. So other words I had electrical background. Well when I had my place put in I just went ahead and let an electrician hook everything up. Everything went fine for about eight years. Then when I build a CNC machine things started acting crazy. For some reason my cable and internet line kept getting shorted out AKA cooked. Wasn't making any sense it happened like three times. So I would always go to the box test everything everything would show up good. Well where I was at they would lock the meter box. After replacing the cable lines about three times I finally called The Electric Company to come take their lock off my meter. Obviously I could have done it but you get in trouble for it where I'm at. Once they did I can find the problem very quickly. They had my neutral wire slid up in there but they never tighten the lug. So basically for years my house is running fine off just the wire pushing against the lug. When I would kick on that CNC spindle it would pull all the power through the ground. So it was using any ground it could find. Including the grounding wire for my cable TV. So yeah it's very important to separate your neutral and ground. Makes me wonder how much equipment I lost due to this.
Wow! I recently had to change out a meter socket that had a similar problem. Whoever worked on it never tightened one of the hots coming in. It was fine for years, but when the cold hit this winter, I guess that was too much for the loose connection. Melted some stuff big time.
Wow!
Im most areas, if you call the power company and tell them you cut the lock off and why, they will just replace it next time they check it and no big deal. I've had to do that as couple of times to remove the meter so I could upgrade the primary service box to a higher capacity. No way to change it without removing the meter.
@@donaldshimkus539 The meter "socket" as well as the meter and lines from the pole all belong to your power company. You should have just called them. With your situation, they would have expedited it.
@@jimdavis6833 in N. Carolina, as in most states, the meter socket is the homeowners property. Only things the power company owns is the meter and the line to the pole.
Smart man. I've been in rooms full of electricians that didn't get this at all. Great explanation and spot on.
Excellent description, I'm learning a lot about AC electric from you. I'm an auto mechanic by trade.
I do want to let you know, when you use your Amp clamp, try not to allow it to snap closed as you are causing damage to your tool.
If I had to venture a guess, I would say that you're probably picking up some small current from low-voltage transformers which are typically grounded to the cabinets that they're mounted in on their secondary common.
Could also be induction from other devices drawing current
Unwanted ground current is probably shared ground current from the main panel due to a better/good ground in the subpanel. Think of a parallel path to ground.
Good video, thanks for the well articulated description of the panel grounding issue.
agree, in other words, the N is not zero volt at main panel.
Beginner here, I love how you explain things. Thank-you
I have watched at least 4 other explanations but this is the one that got me to actually understand it! Big thanks!
Not Only Does Ben know his....Stuff! He is an Excellent Teacher...Codous and THUMBS-UP...Thx. Vince
Spelled "kudos"
NO. NO he is NOT and excellent teacher. He is obviously not a Master Electrician let alone an Electrical Engineer. He should not be teaching as he is learning and "discovering" things that he did not know before. This is pure lunacy. Countless times he said "Power" when "Current" was the proper term.
Check your refrigerator. Fan motors operate in a damp environment and leak current into the ground system. Refrigerators often will trip a GFCI.
@@michaeljorgensen790 makes me cringe a bit, "amp meter" rather than ammeter too, 0.9A rather than 900mA , basic terminology should be fluent for anyone with reasonable experience.
Guys suppose that we have unbalance phases in our electrical system, as a result our neutral wire carries certain amount of current back to the source let's say 20 A with 5 V to the transformer. Why do engineers say that connecting that neutral wire to a ground rod on the transformer will cause the neutral to be 0 V? Isn't voltage suppose to be energy per charged particle? If so, then how come those 20 A can make it to the transformer? Like with what energy per charged particle can those electrons get to the transformer if their potencial energy was taken ? I hope you can undestand my point and help me out with this question that nobody in colombia knows how respond to.
Thank you, thank you, and thank you for making this detailed video. Finally someone who explains it in detail why you separate the neutral and ground!
I'm sure there are even more reasons than what I explained here but this is a good start. Thanks for watching and for subscribing!
@@BenjaminSahlstrom See my comment for the lightning protection aspects.
@@BenjaminSahlstrom The most important reason for not bonding them is for lighting protection. If you have the neutral and ground buses bonded and theres a lightning strike and you don't have a good enough earth bond with your grounding grid you could potentially fry everything in your house, not to mention someone possibly getting a nasty shock. It's the same reason Utilities are required to drive two grounds at the pole on Delta systems, (where theres no system neutral), to separate the transformers lightning protection from the customers service, hoping to avoid sending a lightning shot into the customers home if the transformer takes a shot. This is also a possible reason for the remaining stray amps on your sub panel ground. If your sub panel's grounds have a better earth bond than your main panel's, you could be getting back feed from your main panel's neutral bus, back through the ground wire into your sub panel's ground bus. It can be a needle in a haystack though, as we get this call a couple times a week, where a telephone or a cabe tech won't hook up someones service because of stray amps on the customers ground.
This is the best video explanation I have watched on this subject. Thank You.
Benjamin, I stumbled into your channel by chance and I am so glad that I did. I used to be a journeyman electrician many years ago. I still love electrical work and your channel is just that interesting to me. BTW, I subscribed!
I like this kind of video where the guy is not afraid to challenge the norm and look around and discover "issues" and not worry about the armchair electricians on TH-cam. The reason why is because it challenges me as well. I am a construction inspector and I do a lot of electrical inspections. In this scenario I would also look out at the MAIN service entrance panel. You could be getting a small crossover of amps from the neutral to the ground out there and it is carrying all the way thru the system into the house. Anyway good job with this video. I never thought of running a test like this when I found a subpanel bonded like that.
I believe that in order to have current flowing from the panel outside into the house, there would need to be a high-resistance or open center tap on that transformer.
As a 3rd generation carpenter ive spent a whole lot of time talking to electricians, i cant say ive ever enjoyed it. That being said, i just subscribed to your channel and clicked the bell so i can be notified of any new videos you share with us. Thank you for not being a condescending jackass and giving us a very thorough explanation WITHOUT the ever present patronizing delivery that ive come to expect from a Sparky lol. Great video, and thank you for sharing it. Stay Safe.
One of the best explanations on this subject I have seen. I am a geek about this stuff.
One of the better demonstrations in practical terms! Great vid!
Dear Ben, love your explanation here! You do a wonderful job representing our great trade. I would say that the difference in potential between the ground and neutral would represent induction in appliances and harmonic distortion from the use of fluorescent lighting and certainly LED lighting. I am retired from working in the field, however, harmonic distortion should be on our radar as we see the use of electronics in the home. The sub-panel grounding is in my view very interesting. I have always understood that the NEC requires a separate ground not connected to the neutral bar simply because we need the main breaker feeding the subpanel to open as quickly as possible if there is a fault. Multiple paths to ground would provide a pathway for current to circulate through the house and injure people and potentially prevent the main breaker from opening.
Question 1. Is there a dedicated, unique and special Grounding for Sensitive Electronic Equipment?
2 Question.
In the event of a lightning strike near my property is it recommended to unplug my electronic devices?
3 Question. Why is there always a little (0.3 Amps) current flowing from the neutral bus bar (on the main panel) to the ground rod ?
Does it mean that some of that current could leak out
through the equipment grounding conductor form the main panel to the sup panel energizing the equipments conected to the EGC?
I would appreciate it so much if you help me answering those 3 questions.
correct, each builing /subpannel requires its own grounding rod(s)
@@miguelac6872 Hi Miguel, I will try my best to answer your questions as I understand theory and interpret the NEC rules.
#1. Isolated ground devices and wiring is used in commercial installations and healthcare facilities where critical equipment is in use.
#2. Grounding electrode wiring is meant to help with transient voltage from lightning. That said, there are several devices available to help protect sensitive equipment from a surge of voltage. Stil, if you have something particularly sensitive and valuable, it's a good idea to unplug it.
#3. Some current on the neutral bar can be seen in a normal circumstance. Electronic loads cause harmonic distortion and as a result causes a non-linear load in which the current and voltage becomes out of sync with the rate of hertz. The resulting out of sync value of voltage and current goes to the neutral and then back to the source of generation. If the neutral conductor remains intact all of the way to the source, all is good. We have to be aware of the amount "unbalanced" load on the neutral conductor and size it appropriately. With regard to your question about leaking current? Everything in an electrical service and panel is designed to be bonded and grounded to ensure that there is a effective ground fault current path to the source so that the over current device can open and prevent electrocution. Current takes the least path of resistance to the source. Please be sure to correct me if I am wrong about this, it's been a number of years since I thought about this information. I always found that mikeholt.com is a wonderful source of current NEC and theory information. Best
@@frankie21963 I have to disagree with a statement you made. “Current takes the least path of resistance.” This is incorrect. Current takes all the paths, but will be highest on the path of the least resistance. That is the point of this discussion in the first place, and the thing that many seem to not be understanding. If there is a path available, even if that path is not the best/designed path, electric current will take it also, not instead of the designed path.
@@CaseDadToo, I believe you're correct. However, the context of the NEC and protecting life and property, the goal is to avoid multiple pathways so that the main breaker has enough current to open.
You do an excellent job of explaining things in a way that’s easy to follow! Subbed.
Helped me understand much more than I did. Very clear explanation. Thanks.
Finally understand the "why" to this bonding situation. Great job.
Your small current on the EGC: induced as others mentioned, but also ground and neutral are still connected at the main panel. Ground from your subpanel still offers a path.