FINALLY, this is a topic that surprisingly little people have attempted to explain and in a simple and yet deep well put together way. It's honestly felt like a roadblock for electronics to me, google searches only get you so far. Thanks :)
EXACTLY!!! I feel like nobody fucking understands what it means and so just rehash what others say. Hobby electronics people just use wires for everything, and I have never met an electrician who actually knows the physics intimately. They all just again rehash what they heard before without ever questioning it. All trades are like that tbh. Its disappointing. Its like the man version of beauty pseudoscience
I always make sure to include a few hundred grams of soil inside of every product I design, ensuring a reliable ground connection for the enclosure by shoving a wire into the soil and guaranteeing safety of the device. Proper grounding is very important! Sorry, I had to.
In North America I often see “common” on schematics where it’s not really an earth ground like, for example, on circuit boards and vehicles. I have been involved in many situations where that distinction indeed matters, and the more experienced the electrician or electrical engineer, the more they seem to care about the distinction in the documentation. My circuit board designs often have had a different net for common and earth ground so that the coupling between the two can be managed.
This is a topic that is a bit specialized, but there can be reasons to have separate "grounds" (a.k.a. signal returns) for analog and digital circuitry on a board. A metal housing might need to act as a shield against RF noise, and might need to have special care taken when connecting it to the signal returns. This is typically referred to as a chassis ground. These issues usually come under the heading of electromagnetic compatibility, and are discussed in those sorts of texts. As with many things, you can get by for quite a while without knowing too much about it.
@@prolarkaIt's used in particular when you have circuits that are mixed analog, digital and power electronics. Most of the time, each of those have their own specific common reference, and sometimes it's even not allowed in the electrical code to have a shared ground between the power (high voltage) and control (low voltage) parts of the circuit.
Ground loops are one of those things that really deserve explaining. They are unintuitive and can have some major impacts on circuits, even ones that are seemingly unrelated.
Where I live in Portland Oregon the utility uses earth ground return for the high voltage distribution to residential neighborhoods. That means that on the top of the power pole there is only a single conductor coming from the utility that then feeds into a transformer. The other conductor that goes into the transformer makes its way down the pole and into the ground which completes the circuit with a similar conductor stuck into the ground back at the power distribution station. (Over a km away) I can only assume that back in the 1920s when they put the power in this neighborhood , this saved on copper. There are of course big warnings on this ground conductor that makes its way down the pole telling you not to cut it since if you did, that would then put that loose end attached to the transformer at some very high voltage. It's pretty fascinating that they did it this way and I think it's somewhat unusual for inside a city. It also means if a single tree branch falls on the HV conductor nothing happens but if a tree falls on that's still attached to the ground, you get a short circuit. I have no idea if this ends up being more or less reliable in the long run. On top of that, my house has earth ground with a rod driven into the ground. My earth grounding rod is probably only 25 m from the power pole which has the transformer on it with the earth ground return rod... It's all fascinating that it all just works and goes to show how amazing of a conductor the earth really is.
@@j--xe3ke remember that residential power in the US is split-phase, so the lack of a neutral on one side of the transformer is really no matter, since the other side is gavanically isolated anyway. The neutral, which is bonded to ground at the home, is the center tap of the 240V secondary of that pole transformer. The two 120V phases created this way are then referenced to that incoming neutral. The distribution neutral not being present means nothing in this situation. Although, yeah. Having a broken ground end up exposing a 11 kV floating potential is not great.
A couple of clarifications, one short, one long. 1) My understanding is that in North America the use of the term Ground is synonymous with Earth. In Europe we tend to use Earth to refer to the Protective Earth (PE) connection, and sometimes a functional earth in RF systems, and use the term ground for all other functional 0V connections. 2) There can be many different earth/ground networks for many different reasons in a system, and these are often designated using different symbols in schematics and on connector markings. When using international electrical safety standards, such as ISO, IEC and EN standards, the symbol usually used by Great Scott consisting of three horizontal lines with decreasing length top to bottom, making a roughly triangular shape, is reserved for the Protective Earth (PE) connection only. Functional ground connections, such as the common 0V network in analogue and digital circuits, and which is not intended to carry fault current to protect users from electric shock, use different symbols. In my design schematics I use an open triangle for low current functional ground networks and a filled triangle for high current power ground connections. Some people use a thick horizontal line instead. But I only ever use the three horizontal line symbol for PE connections to conform to safety standards. I wouldn’t want my circuit to be misunderstood and for an electrician to wire a PE connection to a circuit that was not capable of handling fault currents and was not connected to Protective Earth by a sufficiently low impedance to ensure safety in the event of a fault.
I think your understanding is correct, though I would put it a different way: In the US (not sure about Canada, etc), instead of making a distinction between "earth" vs "ground" (which I personally think is needlessly confusing, really), the two concepts are formally identified as "protective ground" and "signal ground" instead. However, when the distinction is not necessary/important, both can (and often are) abbreviated as simply "ground", for convenience.
In German, it's usual to refer to the Protective Earth as "Erde" (the German word for earth) or also as "Erdung" (a connection to earth), while the English word "Ground" is used for the common zero voltage in a circuit or something. (I'm not an electrician or anything, but that's how I as an electronics enthusiast know the words.)
Protected Earth is often specified with a circle while chasis groud uses slanted vertical lines. Open triangle is used for signal ground. The horizontal line triangle "ground" is too often used for the negative electrode of a battery or power supply.
Re 2) When conforming to proper specs, sure different symbols for different 0V potentials. However, when a circuit only has a single 0V potential it's common to use the three horizontal line ground. Here's an interesting fact, Desktop PC power supplies are deliberately NOT isolated. The 0V rail is explicitly tied to the metal case, which is tied to ground.
I'm an engineer who works in the grounding field; my favorite part of grounding is the research performed by Dalziel and Lee to determine the human body's withstand to various voltages and currents. Their research is the basis behind the decision making process for various overcurrent protective devices. Your video is great and does a good job summarizing the basics behind grounding
i'm going to copy/paste another reply (slightly extended here)i just posted under another thread in this video, without going into how many miliamps kill humans, because it's beside point, and because many places have no protection whatsoever: neutral is always grounded on substation (step down transformer) side. and that's exactly what killed 1000s of humans in the past. ie prioritizing the protection of equipment (transformers, generators) vs. protection of humans. because if you don't ground neutral, you can't kill a human, electricity has no will to go to ground when it has a better path (ie the other wire) , but this layout increases chances of lightning destroying equipment of the electric grid. one more thing to mention: many places in the world (probably half the world) lack both rcd and grounding at customer's side, which means that a) contact of live wire to metal housing won't trip the rcd or fuse b) it's easy to end up dead (if you get a good ground connection, for example outside, for example construction site) even if you don't hold live in one hand and neutral in other. why? because neutral is always grounded at substation and you'll get electrocuted via live and earth. no need for 2nd wire if earth is your 2nd wire. so, beware of all exposed metal that potentially carries charge. you don't know if protection is employed at that circuit. it's good to have rcd and grounding, but this was not installed in many old buildings and houses, and it never will be installed. esp. in the "non western world".
I am absolutely in awe at how nice and tidy modern German electrical panels are in general. Good use of plastic for touch surfaces and electrical boxes. In Canada, we just love making everything out of stamped steel like we did 100 years ago and earth the ever-loving heck out of everything. Leaves a lot of safety in the hands of the installer, and much room for error.
4:41 Germany uses the TN-C grid system (Earth and Neutral connected together in distributionpanel) but also the TT electric grid system (Earth and Neutral separated). If you have a TT electric grid system, and the Neutral wire comes in contact with the PE wire (chassis home device etc....) your RCD will also trip. Here in Belgium we use the TT electric grid system, and depending on the load of the grid, and how far removed from the grid transformer, there can be a voltage between Neutral and PE between 0,5V up to 5V. The exact amount of current that is available i'm not sure off, but it is way above 100mA because i have seen RCD's of 100mA trip when the Neutral touched the PE wire. Because the current in the PE wire is not monitored by the electricity company, this voltage / current between Neutral and PE is in fact free electricity if you stay below the tripping point of the RCD. 🙂 Grtz
Ah, that explains why the RCD always tripped, when I cut wires with only the breaker disconnected. I always thought it was bad wiring or devices that created that neutral to ground voltage.
@@j--xe3ke , with 500mW you can run some small LED's, but in reality is less then 500mW. The 5V is somewhat maximum that is possible between Neutral and Earth. In reality here at home, i useally measure arround 1,5 to 1,8V (i'm not measuring this every day). With a RCD of 30mA installed for the entire house, that leave not much room, max 15a20mA of use, because there is always leakage present due the X and Y capacitors leakage in switching powersupplies through the entire house. So with 1,8V at 20mA it's only 35mW, enough for a couple small LED's. With a Joule thief, it can be scaled up a little for more LED's.
Here in India we follow TT earthing system. Without a RCCB, human safety is compromised in TT system. Practically the earth rod resistance cannot be maintained at o. Minimum possible is between 5 to 20 ohms in domestic service. Our house earth pit resistance value is around 12 ohms that too after watering! Between earth and neutral terminals the voltage is around 2V.
my dad was working for a broadcasting company in germany. they had 3 metel towers for sending programs in medium wave frequency. they highest was about 188m in lenght. the stabilisation of the tower was build with steel wires to the ground. the wires had isolators at the end with a cable bridge to secure the towers to ground (earth) from electrostatic charging. the mass of metal in the towers made the electrostatic athmosphere effect very dangerous. my dad demonstrated this to me on a sunny day, he got safety clothes on and attached the ground cable. an ca. 10 cm long electric flash appeared. later he told me, that on rainy days there can be one flash about 30 cm and there can be ca. 10000v and more in it and a lot of current strenght.
This is the best video I have seen in TH-cam about Ground. Thank you! I encourage you to make more videos about ground, in case there is anything interesting to add.
I'm probably too late and there's likely already a comment pointing this out, but: The PE on your mains connection is especially important in Germany because your plugs are never polarized. Since even the earthed ones can be inserted both ways, you can never assume which wire is neutral and which is live. This is not true in North American wiring (for example), where there is supposed to be a guarantee of which one is neutral. Thus, for example, you can put your device's switch and fuse on just the live wire. In practice, though, that's not something that's good to rely on for safety since it's fairly common for them to be reversed by mistake.
I do not see your point. If the case gets energized the fuse will not blow, not even on inside the device. Device fuses are to limit damage to the device.
@@okaro6595If the case is grounded, it cannot be live and grounded at the same time--if a live wire touches the case _something_ will blow, whether it's the device's fuse or a breaker on the mains circuit.
@@okaro6595with respect to the comment I made about the switch--if you have an unpolarized mains plug and a switch only on one leg of it, then if the switch happens to be on the neutral leg, turning the switch off means the whole device is live (since it's connected to the live leg and there's no current flow to drop voltage).This is why many such devices have a double-pole switch to disconnect both legs. The same is true with the fuse.
without earth or ground aka an IT-System we would actually be safer (thats also why its mostly used in hospitals). without any connection to earth the live wire can come loose and onto the housing or rather speaking you could touch one wire without anything happening. if its an checked system (hospitals) electronic devices detect the problem and shutdown the connection or bring an alert if it cannot be turned of. (ie. if its someones life support or simmiliar) if it is unchecked then nothing happens until an second problem occurs (ie. the neutral wire comes also loose or another phase).
Some old televisions had what was called a “live chassis” in which an isolation transformer was pretty imperative to use while performing service work on them to protect the technician from a lethal electrical shock. It is worth noting that a respectable repair shop would perform a leakage test by measuring either the resistance of any exposed metallic pieces on the set to the neutral and live spade on the plug. Or, perform a voltage test of any exposed metallic piece to earth while the set was plugged in and on. . These types of tests were completed before the set was returned to the consumer.
It's not just old TVs and radios. Just about any modern power supply will have circuitry on the "hot" side. On many gadgets such as "smart" switches and other electronic control circuitry it's also common for all the internal circuitry to be live. In terms of safety when troubleshooting you really just need to be careful not to touch the wrong thing. The safest way to do this is to (with the device unplugged) attach clip leads to your test points, then plug it in without touching anything. Personally I've been doing work on an old TV with a true hot chassis (a huge hunk of metal directly connected to one side of the power line) and most of the time I would just plug it in so the chassis is connected to neutral, and I would also use a GFCI. I did get shocked a few times but it was shocks between locations on the chassis, something an isolation transformer cannot not help with.
Some more things I'd add: - Static discharge can start fires, especially if there are any frisky substances in the air like petrol or natural gas. - You sometimes see circuit/signal ground marked as "COM" for "common" to emphasize that it may not actually be ground. - Another thing that is generally grounded is your plumbing, if your pipes are copper (or lead). Thus, most of the water that comes out of taps in your house is likely to be at ground potential.
Another important reason why everything is bonded to ground: isolated systems are impossible at the scale we use it, e.g. the wiring from your transformer to your house but also to all neighbors in the street. Every device, power outlet and wire is galvanically connected to each other within this subsystem. With hundreds of meters of cable you always get a significant capacitive impedance to ground and thus there is always the chance for current (high enough to harm humans) to flow as soon as the circuit gets closed at another point. Ungrounded systems are used for example in operation rooms because the surgery has to continue even if one appliance has an electrical fault.
In Finland PE Ground is called KeVi. That abbrevation comes from words Kelta-Vihreä, meaning Yellow-Green. Official name is "suojajohdin", protector wire, but everyone uses "kevi".
I had an electronic teacher in high school showing a somewhat lost girl how to ground an input by shoving the wire into the plant next to the us. He was great.
I have seen a triangle symbol used for common connections. The commonly-used ground symbol (3 decreasing length horizontal bars as in your video) is then reserved to show the connection to the earth.
This is just a preference thing of the designer, there's no standard usually for electronic schematics. When actual "ground" needs to be referenced in a circuit it's usually mentioned explicitly as PE (Protective Earth) in order to avoid confusion. There are national standards for electrical wiring diagrams however, such as the wiring of your house because those need to ensure proper electrical safety (both from shocking hazards and from electrical fires). So, whenever you see a circuit diagram with electronic components laid out on a PCB, the symbol for the ground there just denotes a common reference point. When you see electrical wiring diagrams, i.e. putting wires through walls etc. you will see an "N" (stands for "Neutral", the actual common point of all your household appliances) and a "PE" (stands for "Protective Earth", the thing that connects to the actual soil eventually) along with L1,2,3, etc (for "Line 1,2,3", i.e. each of the 3 phases coming from the utility pole).
@@InTimeTraveller The symbol shown in this video is actually the IEC symbol for protective earth (iec 60417-5017). So more like an ignorance thing, not a preference thing
Thanx for explaining this, it explains a lot about why losing earth is dangersous. Your electrical system in Germany is very similar to our Country's one.
PEN, nice. A sensible country. I've got 3x230 where I live. Every wire is live all the time. Except for PE, which is completely separate and virtual from all 3 phase wires. Truly fun stuff
Great video! Grounding has always confused me a bit, and it's great to learn this from someone who shares my electrical grid. I just didn't quite understand why the neutral is connected to Earth. 8:56 Hope this means a more in-depth video is in the works!
The neutral is connected to earth for a "well-defined" reference. If you didn't ground any of the active conductors (IT-grid), the wires still form a capacitor between themselves and earth. You wouldn't "get rid" of any earth reference completely in an (extended) distribution grid, but get a "floating" voltage with respect to ground and touching any of the conductors could still lead to a current flowing to earth. Monitoring an IT-grid for insulation problems (to ground) and fault finding is much more difficult than it is in a TN- or TT-grid (where the neutral is grounded). A single (ground) fault in an IT-grid would basically only "degrade" it to a TN-grid, but not result in a short circuit or anything triggering overcurrent protection. Imagine your neighbor tied L1 to earth somehow. In a TN- or TT-grid that would basically result in a short circuit and trip his circuit breaker (and RCD if there is any) and it would be obvious that something is wrong. But in an IT-grid the problem wouldn't be that obvious, but now you (and everyone supplied by the same transformer) now also have L1 at earth potential, and what you think is the "neutral" at 230 V (and L2 and L3 at 400 V) with respect to ground. Technically, everything should still work fine, but you can no longer assume that touching the neutral or a lighting fixture with the (single-pole) switch or circuit breaker turned off is "safe". (And you could draw current from the neutral by connecting devices between neutral and earth, maybe without sufficient overcurrent protection, depending on where the ground fault is located.)
In French, ground usually has two names. If the ground is the earth itself, we will call it earth, and if it’s not (like in electronics), then we call it the Mass, I guess as it acts kind of like a mass that attracts potentials, or something like that, referring to how it’s the 0V point
RCD = GFCI for American viewers. (And GFCI are typically only used in outlet plugs and not at panel breakers in American houses, and typically only in wet areas.)
This video was very informative. I remember being very confused by grounding when I first started off in electronics and the differences between the schematic ground symbols and Earth ground. It took me a while to gain a better understanding of it. Your video is going to help clear it up quite a bit for electronics beginners. The only video that I've come across that is even remotely similar was the video "EEVblog #279 - How NOT To Blow Up Your Oscilloscope!" by Dave Jones of the EEVblog channel. That was somewhat related because it addressed the importance of placing the ground properly for an oscilloscope probe and whether or not it is actually connected to Earth ground (and the consequences of not connecting it properly if that oscilloscope is actually connected to Earth ground). Thank you for being willing to tackle such a difficult subject.
Electronics is such a great varied skills choice. Once there... you are surrounded by a thousand and a half pigeon holes to drop into make contact with. BA Electronics>Cable TV Installer>Substation Helper>Hydro Helper>Apprentice operator>Journeyman Operator>Hydro Operator>System Operator>Cook>Powerhouse Operator>Hydro Operator>System Operator>Groundman>Opal Miner>Opal Cutter/retailer>Gold Mine Mill Electrician>Chrysocolla Miner>Online Gem Sales> NFT Creator. The nimble thrive.
PS the ground wires in Subs and around generators are not bolted together. We have a mold that is filled with a copper melting compound that is lit and melts both wires together in pure copper filling. If not the lightning & fault surges would blow the connections apart & what it was trying to protect would be frizzled to a partial frazzle.
I'd rather just keep it a hobby. There's too much involvement with governments ect. Great list BTW 😂 maybe after 20+ year's and after your required extra schooling for those field's. Engineering is where most want to be but fall back to electricians because of the amount of government work available but most don't realise how little they'll suffer and be underpaid.
@@hulkgqnissanpatrol6121 They're just entirely different types of work for entirely different types of people. Electricians can earn really good money.
Can you make a video about different kinds of grounding? I don't really understand that topic. For example how do we ground electronics in cars which are isolated from the ground? What's a floating ground?
Agreed, I‘d be interested in particular in a video about digital and analogue grounds in PCB designs. The articles and videos I‘ve seen give me the impression that not everyone fully agrees about whether the distinction is really necessary, and if so how to implement ground separation on a PCB. IIRC The Great One has some practical experience building boards with digital and analogue components, and can probably demonstrate when things work well or poorly. Thanks @greatscottlab for another interesting video.
@greatscottlab Yes, please do! Also perhaps go into PEN, why neutral is connected to ground. This used to be a little strange when I was starting out, as it intuitively felt like that should kinda be a short or something.
@@slimhazardAnalog ground can be connected to a digital ground, but often needs a some additional isolation from digital ground as the noise generated from digital circuits is often noisy. Ground needs to be close to 0v in an analog signal, but digital systems often can take a range. 5V digital for example can have a "ground" signal that up to 2 volts and it'll be fine for the most part. If you are dealing with communication circuits it gets way more complicated as they are digital signals that act a lot like analog ones when operating at high speeds.
Interesting fact, a few remote consumers here in Norway only have a single wire feed from the grid. The other "wire" is the ground/soil. It is not common (TN or IT nets mostly used) but it proves that mother earth is a very good conductor.
In Germany, i think, the connection of the neutral to the earth is only allowed in old installations where they had only four conductors ran to the house, now they have to include a dedicated earth wire and the connection of neutral and earth is not allowed
Exactly, here in Italy, earth and neutral are connected together only and I repeat only in the distribution substation. I wrote another comment about it.
They are connected. The issue is just where. In the past they were connected at the socket. Now they are connected at the entry to the house. One needs the connection for the TN system to work. On TT used in for example Italy there is no connection but then one needs a house wide RCD to make the earthing work. One then needs individual RCDs for additional protection in both systems.
Nicely presented. Understanding terminology for AC vs DC is important but can be confusing. Many years ago as I was learning about electronics the fact that so many things were marked as "ground" (such as car battery, DC electronic circuits) confused me. It was only when I learned that such "grounds" were really DC "returns" did it make much more sense to me. So when working with battery or DC circuits I now understand that it is really "return" to the source supply and not an earth "ground". Some people I know who insist on calling it "ground" don't get why it is important to me to call it a "return". The distinction helps me understand that someone knows why the two are different. If someone insists on calling it "ground" then I tend to think they really don't understand the concepts and are just regurgitating what they've heard without knowing why. This approach works for me. Your mileage may vary. A point of view from the U.S.
We get 220VAC from transformers which takes 11 - 13.8kV as input. Transformers are just 2 coils with a couple cm gap between HT and LT. If somehow a phase from HT gets into contact with LT which isn't properly earthed, Nothing will blow up, everything will work properly between phase and neutral but the moment anyone gets close enough to electrical fittings, 6.4KV will zap right through them. Grounding also ensures every substation in an interconnected grid measures the same voltage in each phase wrt to earth, that's essential for fault finding.
I'll just add that a RCD is great, but won't save you if you do something dumb like touching both live and neutral (and are insulated from ground, idk, carpet/ fur slippers). Then it won't trip as you will be just another "regular" load.
Difference is when talking 230VAC it's earth, when its digital electronics it's ground, which simply is 0V common reference. Interested to see your take on PEN though 👍 Also, it is usually good practice to flood any layer with ground.
@@j--xe3ke Well its ground shouldn't be earth. You still want current to run in live and neutral then somehow transformed and isolated to produce a DC voltage supply.
@@j--xe3ke The USB connection (female connector) of a PC is usually digital ground and not PE as the actual case might be. This is to shield the signals going into the cable (which usually also has a ground wire).
For those who do not know, actuall the cause of electrical shock from human touching Live wire (not talking about touching both L & N) is because the bonding of Earth and Neutral somewhere in Grid Transformer. Without any bonding to Earth from Neutral, it would not give shock, that is called Floating system and where L and N are both equally the same (both becomes Live but does not give shock if just one wire is touched). But because N and E are bonded, the Live will go through human body via Earth back to N. This is the precise explanation of electrical shock (or danger) that often people worry about.
Man I wish I could have a teacher like you, you are better than my entire ee department faculty. Nice video! This was also one of the concepts I had difficulty grasping when I started out hobby electronics. Especially the difference between earth ground and chassis ground and voltage reference grounds.
Grounding of equipment is a highly complex issue in a wide range of experimental science and instrumentation, in particular at very low signal voltages and large installations. Ground loops can be the bane of an experimentalist and although one possible solution is to have floating equipment i.e disconnected from ground, this can have serious safety issues, since in many applications you have mixes of very high voltages in the 10's of kV range and signal voltages and currents in the 10-6V or pA ranges. I once had an experimental system which worked extremely well and achieved very high sensitivities without any ground noise issues and then I had to change a few components and power supplies and from one day to the next every thing went to pot and it took me a month to find the causes of the new ground loops being introduced by swapping out equipment.
Very nice and clear explanation. I was taught to have separate grounds for analog and digital parts of the same circuit and only tie them together at one point, where the common entered/left the board. But then, I'm a dinosaur. Thanks for sharing.
My understanding with ELCB is as you say, measures current in Vs current out, but it also helps diagnose causes of issues.. so normal fuses and CB are protection for overload, so essentially too high current draw on a circuit or, there is a live touching neutral/Earth.. an ELCB measures or identifies leaks on the neutral and earth lines since even if the live is off, a neutral touching earth will still cause it to trip.. because there is still a potential between neutral and earth even when the live is disconnected from a circuit.. when you're fault finding, that kinda detail helps a lot..
In the US, the grounding electrode in the actual earth caps the voltage rise from induced currents due to EMP from lightning and also when large inductors (motors) are shut off. The moderate resistance between the building grounding electrode and the one at the transformer on the pole creates an always available path for when the induced current hits an open switch or loss of the combined neutral/ground on the triplex from the transformer that would result in a high voltage spike and possible arcing causing damage or fire. It began as a way to reduce arcing between the windings in large motors. In the past, an induced current on the "hot" side would pass through. motor winding or resistive light then be capped on the neutral. With electronics, we use surge protectors which pass voltage spikes to the bonded neutral rather than let the voltage arc through the transistors and such.
Grounding helps alot with Analog sound equipment, record players needs a ground or else there electric motor can be heard in the cable threw the amplifier. the ground ties to the amplifier to your tuner deck and because the motor noise is canceled threw the Preamp or tuner deck, cannot hook the ground on record players right to ground as they will pickup AM radio waves and there tick or noise can be heard. is why the ground is separated on the plug cause you only want the sound receiver to cancel the motor noises and terminate from that point not earth ground as AM can make added noise. anyways nice and informative stuff there glad someone talked about this as i found alot of homes are not grounded anymore, especially in Canada for some reason.
also want to add not only soil or the simple dirt, playdoah does pretty the same thing. I have done it before during one of the electronic projects with my group
I like the idea of individual circuit breaks on each power and light circuit. This way he lights stay on when the toaster gets a shock to its left cheek. Might cost more but in a home at least the fridge still running and the lights stay on
I repair eleoctronics from agricultural vehicles for a living and more often than you think do we get parts which died due to overvoltage. What happens (almost everytime) is, the farmer or a mechanic decides to weld with an electrical welder on the tractor or some trailer and they don't disconnect their electronical devices or their on-board battery from the machine and the chassis. It would be fine if you disconnected it all, because without a common ground potential, these welding voltages of around 30V (and a shit ton of short circuit current) don't matter to the terminals whatsoever. But if you leave your 3000€ Sprayer Computer connected, you might end up stressing the electronics beyond their ratings until a capacitor or a polyfuse burns itself in confusion and surprise surprise: it's dead. It's the same as touching a live 230V wire with crocs on. Doesn't hurt until you take your other hand and touch the sink :))
6:40 for more info on earth as a conductor, look up SWER Single Wire Earth Return. Used in some remote areas in Australia and New Zealand, possibly others.
It is funny that kids don't get taught that wind can cause static build up........ This is also not very well known, but, in very dry climates like in my country where we are an arid country this is a major problem and also why ground mats and spikes tend to be buried and driven deeper into the ground as the ground dries out to a very deep depth here making the "earthing" of structures that much more involved. Well done.
Next part of The vídeo please teach us about the absorbing properties of our beloved ground from EMP's, and protection from undesired interferences, thats other plus when using a bottom layer ground at PCB design!!
You actually only get chocked because at the generators also have their neutral wires connected to ground. If they didnt there would be no path for the electricity to return and no current would flow. E.g. When you touch one terminal of a battery there is no circuit formed and no electricity flows to ground. This is called a « floating » system, since it is normconnected tomground it is floating. This is sometimes used in hospitals or other confined spaces. In a floating system you need 2 ground faults before electricity can flow trough you when you touch the live wire. Adding more security (but mandates that someone follows up on ground faults and detects if the first one happens)
Very very good content, and i apreciate that you are doing experiments, is fun, and a lot of new thinghs to discover in them. You are a very good young teacher for many peoples, and your job is getting better with every new video!👍👍👍
Unrelated but I wanted to share that I fixed my keyboard by fixing like 10 broken traces ( I had a rage moment years ago on the poor keyboard) but it's now fixed! Thank you,, jumper wires!
as an electrician yeah you dont mess around with 230-240v AC unless you know what your doing .... if it doesn't kill you it WILL hurt ALOT trust me had many shocks in my life just never been grounded
GND is not always ground. With the Shelly devices, GND is placed on the hot cable so that a switch can be used to switch against the hot cable. The processor then hangs between the hot cable with 230 volts and 226.7 volts. This results in 3.3 volts only at the hot end. The rectification is a single diode and capacitor.
Protected Earth uses the horizontal line triangle inside a circle. The 0v reference voltage from a battery or power supply will use it without the circle while a half circle is low noise or functional 0v reference ground. Chassis ground uses slanted vertical lines. Additional grounds use an open triangle with an optional letter like A for analog, D for digital, or other symbols like a circle which means points that have the same potential, but may not be ground.
Seeing you playing with metal casings makes me wonder one thing. Nowadays, I've seen tons of products that uses non-standard metal contacts (Like bolts, plates, etc...) to connect multiple parts that need to be easily detachable, i.e. vacuum robots and the charging stations, or cheap bluetooth headphones with tiny metal rods as contact points. In some DIY proyects I have also seen connections made through bolts whose main purpose was just hold two pieces together. How can I measure the electrical properties of such a connection? Like resistance, max current... you know better than me. I think that a video covering such a thing could be interesting!
@greatscottlab I think there is an error: The earth and neutral are connected together in the distribution cabin, at the output of the low voltage secondary, not in the house, that's how it works in Italy. In this way the RCD can trip even with leakage towards the neutral. Because there will be a potential drop in the neutral wire on the way from the cabin to the house, relative to the ground. To verify this, test measure the voltage between neutral and earth in any outlet. It is usually around 5V but increases proportionally to the loads. Because this also increases the drop on the neutral wire from the cabin to the house.
There are different types of "grounding systems" in use around the world. Here in the US (and Canada) neutral and ground actually are connected in the house's main service panel. From the transformer to the house there is not a dedicated ground wire, only a neutral wire. This neutral is grounded at the transformer as well as each house. This is called a TN-C-S system. A TN-S system like you describe being used in Italy is AFAIK what most of the civilized world usually uses. Some countries (like the UK) could have a different setup depending on the specific install.
So in case there is no rcb or what is that (is it the same as phi relay?) the reason why safety works is because when electricity go out through metal parts, it creates big short and from aperage output the disconnectors shut down the electricity? Because I also thought its not only this, but that grounding the outside metal parts create a "better" short through the earth/ground than through me, so deadly current would flow there and not that much through me when I myself touch it. So I think its not only that the electricity goes off and thus safe, but because lower resistance path through grounding when error occurs so even though there is maybe a path through me as I touch it, but its of higher resistance than the probe deep in ground... I also know that ground reference potential can actually do differ is distance is high enough - what I am not sure when this kicks in though. Like I can choose to put the probe right below the room (because floor gets replaced there soon) where key electronics would maybe benefit it or at outside. I don't think though there is much of a difference. Oh and please explain what the hell happens when some in some houses I hear they at the incoming box of electricity someone connected the neutral and ground wires - I think its mistake, but still some people do this and I really wonder what the real effects would be of putting the incoming neutral together with the internal ground wire... In theory it means that if 230V goes to the grounded surfaces, then neutral becomes of same potential as the live wire - also as a side effect for half the street or so. This way touching neutral is bad for your health as it would have a huge voltage. Then again however this way potential difference between live and neutral would disappear / shrink and hopefully still the current finds lesser resistance through the netural of the system than through my body if I touch the metal parts of bad objects. In this sense according to what I think in theory this "bad practice" is actually not that awful as one might think, but still very bad - but mostly because of hazarding the grid power not because of hazarding touching metal parts where the mains live touch someway.
In my parents house in the 90's we had one water pipe that sometimes gave you a bit of a zap. It was an outside tap. So i wrapped copper around a half meter mild steel rod, drilled a hole in the concrete to expose soil, and drive that rod into the soil with the back end of an axe. Other end of the wire I wrapped around the copper water pipe for about 10cm, then welded it with lead and a torche with way to much flux. It worked. Come to think of it now.... that was maybe not the correct fix. It is only hiding a bigger problem somewhere. I was 15 when i came up that that idea.
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FINALLY, this is a topic that surprisingly little people have attempted to explain and in a simple and yet deep well put together way. It's honestly felt like a roadblock for electronics to me, google searches only get you so far. Thanks :)
I totally agree!
Same! I had some silly doubts which I did not dare to ask on Stackoverflow, but ChatGPT and now Greatscott is there for the rescue!
EXACTLY!!! I feel like nobody fucking understands what it means and so just rehash what others say. Hobby electronics people just use wires for everything, and I have never met an electrician who actually knows the physics intimately. They all just again rehash what they heard before without ever questioning it. All trades are like that tbh. Its disappointing. Its like the man version of beauty pseudoscience
I agree
@@melody3741
Exactly
I have asked about it but everyone just said the same stuff more or less I still don't know what a digital ground is really
I always make sure to include a few hundred grams of soil inside of every product I design, ensuring a reliable ground connection for the enclosure by shoving a wire into the soil and guaranteeing safety of the device. Proper grounding is very important!
Sorry, I had to.
Good practice. Everyone should do that.
Dude don't waste effort, You just have to lay the wire down & connect it with a glass of water.
@@greatscottlab 😂
make sure to have ground fault protection included in the product
meanwhile I am just using wireless grounding technology, way easier xD
In North America I often see “common” on schematics where it’s not really an earth ground like, for example, on circuit boards and vehicles. I have been involved in many situations where that distinction indeed matters, and the more experienced the electrician or electrical engineer, the more they seem to care about the distinction in the documentation.
My circuit board designs often have had a different net for common and earth ground so that the coupling between the two can be managed.
Thanks for the feedback. Interesting.
There are different symbols for real earthing and common point. Nobody knows them unless they have to work on something where it matters.
This is a topic that is a bit specialized, but there can be reasons to have separate "grounds" (a.k.a. signal returns) for analog and digital circuitry on a board. A metal housing might need to act as a shield against RF noise, and might need to have special care taken when connecting it to the signal returns. This is typically referred to as a chassis ground. These issues usually come under the heading of electromagnetic compatibility, and are discussed in those sorts of texts. As with many things, you can get by for quite a while without knowing too much about it.
@@prolarkaIt's used in particular when you have circuits that are mixed analog, digital and power electronics. Most of the time, each of those have their own specific common reference, and sometimes it's even not allowed in the electrical code to have a shared ground between the power (high voltage) and control (low voltage) parts of the circuit.
Common is called "Neutral" in Europe, as well as in UK, as well as in Australia, and other former British territories. 🇪🇺🇬🇧
Ground loops are one of those things that really deserve explaining. They are unintuitive and can have some major impacts on circuits, even ones that are seemingly unrelated.
Where I live in Portland Oregon the utility uses earth ground return for the high voltage distribution to residential neighborhoods. That means that on the top of the power pole there is only a single conductor coming from the utility that then feeds into a transformer. The other conductor that goes into the transformer makes its way down the pole and into the ground which completes the circuit with a similar conductor stuck into the ground back at the power distribution station. (Over a km away) I can only assume that back in the 1920s when they put the power in this neighborhood , this saved on copper. There are of course big warnings on this ground conductor that makes its way down the pole telling you not to cut it since if you did, that would then put that loose end attached to the transformer at some very high voltage.
It's pretty fascinating that they did it this way and I think it's somewhat unusual for inside a city. It also means if a single tree branch falls on the HV conductor nothing happens but if a tree falls on that's still attached to the ground, you get a short circuit. I have no idea if this ends up being more or less reliable in the long run.
On top of that, my house has earth ground with a rod driven into the ground. My earth grounding rod is probably only 25 m from the power pole which has the transformer on it with the earth ground return rod... It's all fascinating that it all just works and goes to show how amazing of a conductor the earth really is.
In the UK that would be called a TT sytem. terra terra
@@UberAlphaSirustrue, but in the classic domestic TT system there is still a neutral conductor
This sounds scary for many reasons
@@j--xe3ke remember that residential power in the US is split-phase, so the lack of a neutral on one side of the transformer is really no matter, since the other side is gavanically isolated anyway. The neutral, which is bonded to ground at the home, is the center tap of the 240V secondary of that pole transformer. The two 120V phases created this way are then referenced to that incoming neutral. The distribution neutral not being present means nothing in this situation.
Although, yeah. Having a broken ground end up exposing a 11 kV floating potential is not great.
excellent video, bromigo. Grounding is a deep subject and you're giving some very clear explanations
Thanks for the feedback :-) Happy to hear it.
90 percent of my electronic learning was learnt on this channel..
@@greatscottlabsay, how does ground work on a spaceship?
In some places it is up to 9 meters deep. 🤔
It's very important to ground our knowledge in the basics.
A couple of clarifications, one short, one long.
1) My understanding is that in North America the use of the term Ground is synonymous with Earth. In Europe we tend to use Earth to refer to the Protective Earth (PE) connection, and sometimes a functional earth in RF systems, and use the term ground for all other functional 0V connections.
2) There can be many different earth/ground networks for many different reasons in a system, and these are often designated using different symbols in schematics and on connector markings. When using international electrical safety standards, such as ISO, IEC and EN standards, the symbol usually used by Great Scott consisting of three horizontal lines with decreasing length top to bottom, making a roughly triangular shape, is reserved for the Protective Earth (PE) connection only. Functional ground connections, such as the common 0V network in analogue and digital circuits, and which is not intended to carry fault current to protect users from electric shock, use different symbols. In my design schematics I use an open triangle for low current functional ground networks and a filled triangle for high current power ground connections. Some people use a thick horizontal line instead. But I only ever use the three horizontal line symbol for PE connections to conform to safety standards. I wouldn’t want my circuit to be misunderstood and for an electrician to wire a PE connection to a circuit that was not capable of handling fault currents and was not connected to Protective Earth by a sufficiently low impedance to ensure safety in the event of a fault.
I think your understanding is correct, though I would put it a different way: In the US (not sure about Canada, etc), instead of making a distinction between "earth" vs "ground" (which I personally think is needlessly confusing, really), the two concepts are formally identified as "protective ground" and "signal ground" instead. However, when the distinction is not necessary/important, both can (and often are) abbreviated as simply "ground", for convenience.
In German, it's usual to refer to the Protective Earth as "Erde" (the German word for earth) or also as "Erdung" (a connection to earth), while the English word "Ground" is used for the common zero voltage in a circuit or something.
(I'm not an electrician or anything, but that's how I as an electronics enthusiast know the words.)
Protected Earth is often specified with a circle while chasis groud uses slanted vertical lines. Open triangle is used for signal ground. The horizontal line triangle "ground" is too often used for the negative electrode of a battery or power supply.
Living in the US, I've also heard these distinguished as "ground" and "earth ground".
Re 2)
When conforming to proper specs, sure different symbols for different 0V potentials. However, when a circuit only has a single 0V potential it's common to use the three horizontal line ground. Here's an interesting fact, Desktop PC power supplies are deliberately NOT isolated. The 0V rail is explicitly tied to the metal case, which is tied to ground.
I'm an engineer who works in the grounding field; my favorite part of grounding is the research performed by Dalziel and Lee to determine the human body's withstand to various voltages and currents. Their research is the basis behind the decision making process for various overcurrent protective devices. Your video is great and does a good job summarizing the basics behind grounding
i'm going to copy/paste another reply (slightly extended here)i just posted under another thread in this video, without going into how many miliamps kill humans, because it's beside point, and because many places have no protection whatsoever:
neutral is always grounded on substation (step down transformer) side.
and that's exactly what killed 1000s of humans in the past.
ie prioritizing the protection of equipment (transformers, generators) vs. protection of humans.
because if you don't ground neutral, you can't kill a human, electricity has no will to go to ground when it has a better path (ie the other wire) , but this layout increases chances of lightning destroying equipment of the electric grid.
one more thing to mention: many places in the world (probably half the world) lack both rcd and grounding at customer's side, which means that
a) contact of live wire to metal housing won't trip the rcd or fuse
b) it's easy to end up dead (if you get a good ground connection, for example outside, for example construction site) even if you don't hold live in one hand and neutral in other.
why? because neutral is always grounded at substation and you'll get electrocuted via live and earth.
no need for 2nd wire if earth is your 2nd wire.
so, beware of all exposed metal that potentially carries charge. you don't know if protection is employed at that circuit.
it's good to have rcd and grounding, but this was not installed in many old buildings and houses, and it never will be installed. esp. in the "non western world".
There is a farmer joke somewhere around “grounding field,” but I can’t find it. Let me know if anyone else finds it.
I am absolutely in awe at how nice and tidy modern German electrical panels are in general. Good use of plastic for touch surfaces and electrical boxes.
In Canada, we just love making everything out of stamped steel like we did 100 years ago and earth the ever-loving heck out of everything. Leaves a lot of safety in the hands of the installer, and much room for error.
4:41 Germany uses the TN-C grid system (Earth and Neutral connected together in distributionpanel) but also the TT electric grid system (Earth and Neutral separated).
If you have a TT electric grid system, and the Neutral wire comes in contact with the PE wire (chassis home device etc....) your RCD will also trip.
Here in Belgium we use the TT electric grid system, and depending on the load of the grid, and how far removed from the grid transformer, there can be a voltage between Neutral and PE between 0,5V up to 5V.
The exact amount of current that is available i'm not sure off, but it is way above 100mA because i have seen RCD's of 100mA trip when the Neutral touched the PE wire.
Because the current in the PE wire is not monitored by the electricity company, this voltage / current between Neutral and PE is in fact free electricity if you stay below the tripping point of the RCD. 🙂 Grtz
Nice to know, thx😀 you could plug a usb charger between N and PE😏
Ah, that explains why the RCD always tripped, when I cut wires with only the breaker disconnected. I always thought it was bad wiring or devices that created that neutral to ground voltage.
Well, you could try to get free energ... uhm... I mean electrical power without paying; but what's your plan how to use 500mW at best?
@@j--xe3ke , with 500mW you can run some small LED's, but in reality is less then 500mW. The 5V is somewhat maximum that is possible between Neutral and Earth. In reality here at home, i useally measure arround 1,5 to 1,8V (i'm not measuring this every day). With a RCD of 30mA installed for the entire house, that leave not much room, max 15a20mA of use, because there is always leakage present due the X and Y capacitors leakage in switching powersupplies through the entire house. So with 1,8V at 20mA it's only 35mW, enough for a couple small LED's. With a Joule thief, it can be scaled up a little for more LED's.
Here in India we follow TT earthing system. Without a RCCB, human safety is compromised in TT system. Practically the earth rod resistance cannot be maintained at o. Minimum possible is between 5 to 20 ohms in domestic service. Our house earth pit resistance value is around 12 ohms that too after watering!
Between earth and neutral terminals the voltage is around 2V.
my dad was working for a broadcasting company in germany. they had 3 metel towers for sending programs in medium wave frequency. they highest was about 188m in lenght. the stabilisation of the tower was build with steel wires to the ground. the wires had isolators at the end with a cable bridge to secure the towers to ground (earth) from electrostatic charging. the mass of metal in the towers made the electrostatic athmosphere effect very dangerous. my dad demonstrated this to me on a sunny day, he got safety clothes on and attached the ground cable. an ca. 10 cm long electric flash appeared. later he told me, that on rainy days there can be one flash about 30 cm and there can be ca. 10000v and more in it and a lot of current strenght.
This is the best video I have seen in TH-cam about Ground. Thank you! I encourage you to make more videos about ground, in case there is anything interesting to add.
Great Scott really gives some useful tips n information
Glad you think so!
Thanks for clearing this out. I have heard other people complaining but it did. It really sink in completely before. Thanks again
You’re slowly turning into electroboom.
I'm probably too late and there's likely already a comment pointing this out, but: The PE on your mains connection is especially important in Germany because your plugs are never polarized. Since even the earthed ones can be inserted both ways, you can never assume which wire is neutral and which is live.
This is not true in North American wiring (for example), where there is supposed to be a guarantee of which one is neutral. Thus, for example, you can put your device's switch and fuse on just the live wire. In practice, though, that's not something that's good to rely on for safety since it's fairly common for them to be reversed by mistake.
I do not see your point. If the case gets energized the fuse will not blow, not even on inside the device. Device fuses are to limit damage to the device.
@@okaro6595If the case is grounded, it cannot be live and grounded at the same time--if a live wire touches the case _something_ will blow, whether it's the device's fuse or a breaker on the mains circuit.
@@okaro6595with respect to the comment I made about the switch--if you have an unpolarized mains plug and a switch only on one leg of it, then if the switch happens to be on the neutral leg, turning the switch off means the whole device is live (since it's connected to the live leg and there's no current flow to drop voltage).This is why many such devices have a double-pole switch to disconnect both legs. The same is true with the fuse.
without earth or ground aka an IT-System we would actually be safer (thats also why its mostly used in hospitals).
without any connection to earth the live wire can come loose and onto the housing or rather speaking you could touch one wire without anything happening.
if its an checked system (hospitals) electronic devices detect the problem and shutdown the connection or bring an alert if it cannot be turned of. (ie. if its someones life support or simmiliar)
if it is unchecked then nothing happens until an second problem occurs (ie. the neutral wire comes also loose or another phase).
Some old televisions had what was called a “live chassis” in which an isolation transformer was pretty imperative to use while performing service work on them to protect the technician from a lethal electrical shock.
It is worth noting that a respectable repair shop would perform a leakage test by measuring either the resistance of any exposed metallic pieces on the set to the neutral and live spade on the plug. Or, perform a voltage test of any exposed metallic piece to earth while the set was plugged in and on. . These types of tests were completed before the set was returned to the consumer.
It's not just old TVs and radios. Just about any modern power supply will have circuitry on the "hot" side. On many gadgets such as "smart" switches and other electronic control circuitry it's also common for all the internal circuitry to be live.
In terms of safety when troubleshooting you really just need to be careful not to touch the wrong thing. The safest way to do this is to (with the device unplugged) attach clip leads to your test points, then plug it in without touching anything.
Personally I've been doing work on an old TV with a true hot chassis (a huge hunk of metal directly connected to one side of the power line) and most of the time I would just plug it in so the chassis is connected to neutral, and I would also use a GFCI. I did get shocked a few times but it was shocks between locations on the chassis, something an isolation transformer cannot not help with.
Some more things I'd add:
- Static discharge can start fires, especially if there are any frisky substances in the air like petrol or natural gas.
- You sometimes see circuit/signal ground marked as "COM" for "common" to emphasize that it may not actually be ground.
- Another thing that is generally grounded is your plumbing, if your pipes are copper (or lead). Thus, most of the water that comes out of taps in your house is likely to be at ground potential.
my house was made in the 50s and has screw in fuses. looking at your 'fuse box' is like something from a spaceship.
Another important reason why everything is bonded to ground: isolated systems are impossible at the scale we use it, e.g. the wiring from your transformer to your house but also to all neighbors in the street. Every device, power outlet and wire is galvanically connected to each other within this subsystem. With hundreds of meters of cable you always get a significant capacitive impedance to ground and thus there is always the chance for current (high enough to harm humans) to flow as soon as the circuit gets closed at another point. Ungrounded systems are used for example in operation rooms because the surgery has to continue even if one appliance has an electrical fault.
thank you so much for touching on this subject!
Ground is important for way more things than electricity. It's one of my favorite things for standing on too.
Hi @GreatScott! Thank you for presenting that very important topic 🙋🏻♂️
Finally one of my greatest mystery is solved! Thank you!
You did a great job of explaining and demonstrating how important proper grounding really is. Good work, keep it up!
In Finland PE Ground is called KeVi. That abbrevation comes from words Kelta-Vihreä, meaning Yellow-Green. Official name is "suojajohdin", protector wire, but everyone uses "kevi".
I had an electronic teacher in high school showing a somewhat lost girl how to ground an input by shoving the wire into the plant next to the us. He was great.
I have seen a triangle symbol used for common connections. The commonly-used ground symbol (3 decreasing length horizontal bars as in your video) is then reserved to show the connection to the earth.
This is just a preference thing of the designer, there's no standard usually for electronic schematics. When actual "ground" needs to be referenced in a circuit it's usually mentioned explicitly as PE (Protective Earth) in order to avoid confusion. There are national standards for electrical wiring diagrams however, such as the wiring of your house because those need to ensure proper electrical safety (both from shocking hazards and from electrical fires). So, whenever you see a circuit diagram with electronic components laid out on a PCB, the symbol for the ground there just denotes a common reference point. When you see electrical wiring diagrams, i.e. putting wires through walls etc. you will see an "N" (stands for "Neutral", the actual common point of all your household appliances) and a "PE" (stands for "Protective Earth", the thing that connects to the actual soil eventually) along with L1,2,3, etc (for "Line 1,2,3", i.e. each of the 3 phases coming from the utility pole).
@@InTimeTraveller The symbol shown in this video is actually the IEC symbol for protective earth (iec 60417-5017). So more like an ignorance thing, not a preference thing
@@WhiteBreamQuite so! My comment details the different networks called earth/ground and why it’s important to reserve the PE symbol for PE use.
@@BillySugger1965Yeah, but the IEC PE symbol specifically uses a circle around it to specify that it is protective earth.
Thanx for explaining this, it explains a lot about why losing earth is dangersous. Your electrical system in Germany is very similar to our Country's one.
8:40 this was the best explanation i’ve ever heard on grounding. Thanks
PEN, nice. A sensible country. I've got 3x230 where I live. Every wire is live all the time. Except for PE, which is completely separate and virtual from all 3 phase wires. Truly fun stuff
Great video! Grounding has always confused me a bit, and it's great to learn this from someone who shares my electrical grid. I just didn't quite understand why the neutral is connected to Earth.
8:56 Hope this means a more in-depth video is in the works!
I was hoping this too!
The neutral is connected to earth for a "well-defined" reference. If you didn't ground any of the active conductors (IT-grid), the wires still form a capacitor between themselves and earth. You wouldn't "get rid" of any earth reference completely in an (extended) distribution grid, but get a "floating" voltage with respect to ground and touching any of the conductors could still lead to a current flowing to earth. Monitoring an IT-grid for insulation problems (to ground) and fault finding is much more difficult than it is in a TN- or TT-grid (where the neutral is grounded). A single (ground) fault in an IT-grid would basically only "degrade" it to a TN-grid, but not result in a short circuit or anything triggering overcurrent protection.
Imagine your neighbor tied L1 to earth somehow. In a TN- or TT-grid that would basically result in a short circuit and trip his circuit breaker (and RCD if there is any) and it would be obvious that something is wrong. But in an IT-grid the problem wouldn't be that obvious, but now you (and everyone supplied by the same transformer) now also have L1 at earth potential, and what you think is the "neutral" at 230 V (and L2 and L3 at 400 V) with respect to ground. Technically, everything should still work fine, but you can no longer assume that touching the neutral or a lighting fixture with the (single-pole) switch or circuit breaker turned off is "safe". (And you could draw current from the neutral by connecting devices between neutral and earth, maybe without sufficient overcurrent protection, depending on where the ground fault is located.)
In French, ground usually has two names. If the ground is the earth itself, we will call it earth, and if it’s not (like in electronics), then we call it the Mass, I guess as it acts kind of like a mass that attracts potentials, or something like that, referring to how it’s the 0V point
RCD = GFCI for American viewers. (And GFCI are typically only used in outlet plugs and not at panel breakers in American houses, and typically only in wet areas.)
This video was very informative. I remember being very confused by grounding when I first started off in electronics and the differences between the schematic ground symbols and Earth ground. It took me a while to gain a better understanding of it. Your video is going to help clear it up quite a bit for electronics beginners.
The only video that I've come across that is even remotely similar was the video "EEVblog #279 - How NOT To Blow Up Your Oscilloscope!" by Dave Jones of the EEVblog channel. That was somewhat related because it addressed the importance of placing the ground properly for an oscilloscope probe and whether or not it is actually connected to Earth ground (and the consequences of not connecting it properly if that oscilloscope is actually connected to Earth ground).
Thank you for being willing to tackle such a difficult subject.
I remember that video! Watched it years ago before I bought my oscilloscope and went on a deep dive into grounding concepts.
Electronics is such a great varied skills choice. Once there... you are surrounded by a thousand and a half pigeon holes to drop into make contact with. BA Electronics>Cable TV Installer>Substation Helper>Hydro Helper>Apprentice operator>Journeyman Operator>Hydro Operator>System Operator>Cook>Powerhouse Operator>Hydro Operator>System Operator>Groundman>Opal Miner>Opal Cutter/retailer>Gold Mine Mill Electrician>Chrysocolla Miner>Online Gem Sales> NFT Creator. The nimble thrive.
PS the ground wires in Subs and around generators are not bolted together. We have a mold that is filled with a copper melting compound that is lit and melts both wires together in pure copper filling. If not the lightning & fault surges would blow the connections apart & what it was trying to protect would be frizzled to a partial frazzle.
I’d rather be an electrical engineer
@@FemboyEngineer That's another great option.
I'd rather just keep it a hobby.
There's too much involvement with governments ect.
Great list BTW 😂 maybe after 20+ year's and after your required extra schooling for those field's.
Engineering is where most want to be but fall back to electricians because of the amount of government work available but most don't realise how little they'll suffer and be underpaid.
@@hulkgqnissanpatrol6121 They're just entirely different types of work for entirely different types of people. Electricians can earn really good money.
Can you make a video about different kinds of grounding? I don't really understand that topic.
For example how do we ground electronics in cars which are isolated from the ground? What's a floating ground?
I can put it on my to do list
@@greatscottlab Thx!
Agreed, I‘d be interested in particular in a video about digital and analogue grounds in PCB designs. The articles and videos I‘ve seen give me the impression that not everyone fully agrees about whether the distinction is really necessary, and if so how to implement ground separation on a PCB. IIRC The Great One has some practical experience building boards with digital and analogue components, and can probably demonstrate when things work well or poorly. Thanks @greatscottlab for another interesting video.
@greatscottlab Yes, please do! Also perhaps go into PEN, why neutral is connected to ground. This used to be a little strange when I was starting out, as it intuitively felt like that should kinda be a short or something.
@@slimhazardAnalog ground can be connected to a digital ground, but often needs a some additional isolation from digital ground as the noise generated from digital circuits is often noisy. Ground needs to be close to 0v in an analog signal, but digital systems often can take a range. 5V digital for example can have a "ground" signal that up to 2 volts and it'll be fine for the most part. If you are dealing with communication circuits it gets way more complicated as they are digital signals that act a lot like analog ones when operating at high speeds.
This video was amazing at explaining earth gnd. So happy I found your channel
Interesting fact, a few remote consumers here in Norway only have a single wire feed from the grid. The other "wire" is the ground/soil. It is not common (TN or IT nets mostly used) but it proves that mother earth is a very good conductor.
In Germany, i think, the connection of the neutral to the earth is only allowed in old installations where they had only four conductors ran to the house, now they have to include a dedicated earth wire and the connection of neutral and earth is not allowed
Exactly, here in Italy, earth and neutral are connected together only and I repeat only in the distribution substation. I wrote another comment about it.
They are connected. The issue is just where. In the past they were connected at the socket. Now they are connected at the entry to the house. One needs the connection for the TN system to work. On TT used in for example Italy there is no connection but then one needs a house wide RCD to make the earthing work. One then needs individual RCDs for additional protection in both systems.
Nicely presented. Understanding terminology for AC vs DC is important but can be confusing. Many years ago as I was learning about electronics the fact that so many things were marked as "ground" (such as car battery, DC electronic circuits) confused me. It was only when I learned that such "grounds" were really DC "returns" did it make much more sense to me. So when working with battery or DC circuits I now understand that it is really "return" to the source supply and not an earth "ground". Some people I know who insist on calling it "ground" don't get why it is important to me to call it a "return". The distinction helps me understand that someone knows why the two are different. If someone insists on calling it "ground" then I tend to think they really don't understand the concepts and are just regurgitating what they've heard without knowing why. This approach works for me. Your mileage may vary. A point of view from the U.S.
"Common" is another term, particularly if other voltages are referenced to it.
We get 220VAC from transformers which takes 11 - 13.8kV as input. Transformers are just 2 coils with a couple cm gap between HT and LT. If somehow a phase from HT gets into contact with LT which isn't properly earthed, Nothing will blow up, everything will work properly between phase and neutral but the moment anyone gets close enough to electrical fittings, 6.4KV will zap right through them.
Grounding also ensures every substation in an interconnected grid measures the same voltage in each phase wrt to earth, that's essential for fault finding.
I'll just add that a RCD is great, but won't save you if you do something dumb like touching both live and neutral (and are insulated from ground, idk, carpet/ fur slippers). Then it won't trip as you will be just another "regular" load.
Difference is when talking 230VAC it's earth, when its digital electronics it's ground, which simply is 0V common reference. Interested to see your take on PEN though 👍
Also, it is usually good practice to flood any layer with ground.
And as soon as you connect your (digital electronics) phone to your computer via a usb cable it's ground is earthed. Or is the earth grounded then?
@@j--xe3ke Well its ground shouldn't be earth. You still want current to run in live and neutral then somehow transformed and isolated to produce a DC voltage supply.
@@bogmaerke I'm speaking of desktop PCs. Their metal case is grounded.
@@j--xe3ke The USB connection (female connector) of a PC is usually digital ground and not PE as the actual case might be. This is to shield the signals going into the cable (which usually also has a ground wire).
For those who do not know, actuall the cause of electrical shock from human touching Live wire (not talking about touching both L & N) is because the bonding of Earth and Neutral somewhere in Grid Transformer. Without any bonding to Earth from Neutral, it would not give shock, that is called Floating system and where L and N are both equally the same (both becomes Live but does not give shock if just one wire is touched). But because N and E are bonded, the Live will go through human body via Earth back to N. This is the precise explanation of electrical shock (or danger) that often people worry about.
Thank u for expleaning this thing, It Always got me in the past.
I can see your good work all the way from Africa. 👏👏👏
I do enjoy a "dont try this at home" episode 👍👍
Glad to hear it :-)
Yes, I'm sure the wife wouldn't be happy with finding burn marks on the toaster!! :-D
5:10 The RCCB or residual current circuit breaker is the equivalent to a GFCI or ground fault circuit interrupter in North America.
Well, Great Scott, that was a Great Tutorial. Much better then the lessons in school about 45 years ago.
After watching this video, I am glad, this guy is still alive 😅!
Toasters generally don't have a protective ground in the US. This has always bothered me, since the electrically live heating elements are exposed.
Man I wish I could have a teacher like you, you are better than my entire ee department faculty.
Nice video! This was also one of the concepts I had difficulty grasping when I started out hobby electronics. Especially the difference between earth ground and chassis ground and voltage reference grounds.
If you wanted to trip only the RCB (FID) you should have connected the Neutral wire to the case of your Toaster instead of Live wire.
Grounding of equipment is a highly complex issue in a wide range of experimental science and instrumentation, in particular at very low signal voltages and large installations. Ground loops can be the bane of an experimentalist and although one possible solution is to have floating equipment i.e disconnected from ground, this can have serious safety issues, since in many applications you have mixes of very high voltages in the 10's of kV range and signal voltages and currents in the 10-6V or pA ranges. I once had an experimental system which worked extremely well and achieved very high sensitivities without any ground noise issues and then I had to change a few components and power supplies and from one day to the next every thing went to pot and it took me a month to find the causes of the new ground loops being introduced by swapping out equipment.
Very nice and clear explanation. I was taught to have separate grounds for analog and digital parts of the same circuit and only tie them together at one point, where the common entered/left the board. But then, I'm a dinosaur. Thanks for sharing.
My understanding with ELCB is as you say, measures current in Vs current out, but it also helps diagnose causes of issues.. so normal fuses and CB are protection for overload, so essentially too high current draw on a circuit or, there is a live touching neutral/Earth.. an ELCB measures or identifies leaks on the neutral and earth lines since even if the live is off, a neutral touching earth will still cause it to trip.. because there is still a potential between neutral and earth even when the live is disconnected from a circuit.. when you're fault finding, that kinda detail helps a lot..
In the US, the grounding electrode in the actual earth caps the voltage rise from induced currents due to EMP from lightning and also when large inductors (motors) are shut off. The moderate resistance between the building grounding electrode and the one at the transformer on the pole creates an always available path for when the induced current hits an open switch or loss of the combined neutral/ground on the triplex from the transformer that would result in a high voltage spike and possible arcing causing damage or fire. It began as a way to reduce arcing between the windings in large motors. In the past, an induced current on the "hot" side would pass through. motor winding or resistive light then be capped on the neutral. With electronics, we use surge protectors which pass voltage spikes to the bonded neutral rather than let the voltage arc through the transistors and such.
Shoutout to your ABB electrical cabinet ❤
7:39 That's truly a PCB torture machine!
Grounding helps alot with Analog sound equipment, record players needs a ground or else there electric motor can be heard in the cable threw the amplifier. the ground ties to the amplifier to your tuner deck and because the motor noise is canceled threw the Preamp or tuner deck, cannot hook the ground on record players right to ground as they will pickup AM radio waves and there tick or noise can be heard. is why the ground is separated on the plug cause you only want the sound receiver to cancel the motor noises and terminate from that point not earth ground as AM can make added noise.
anyways nice and informative stuff there glad someone talked about this as i found alot of homes are not grounded anymore, especially in Canada for some reason.
Most A equipment are double insulated so grounding does not help. One ca get rid of the hum by putting a galvanic isolator on the antenna.
That's crazy watching you.Draw something so neat and tidy with your left hand
I am right handed but have dyslexia So even my right hand is Terrible 😂😂
Finally, the explanation I was looking for, thanks!
6:18 Electricitiahh😌
also want to add not only soil or the simple dirt, playdoah does pretty the same thing. I have done it before during one of the electronic projects with my group
In the UK we tend to call the green AC ground "earth" and DC Black negative "ground"
I like the idea of individual circuit breaks on each power and light circuit. This way he lights stay on when the toaster gets a shock to its left cheek. Might cost more but in a home at least the fridge still running and the lights stay on
I repair eleoctronics from agricultural vehicles for a living and more often than you think do we get parts which died due to overvoltage. What happens (almost everytime) is, the farmer or a mechanic decides to weld with an electrical welder on the tractor or some trailer and they don't disconnect their electronical devices or their on-board battery from the machine and the chassis. It would be fine if you disconnected it all, because without a common ground potential, these welding voltages of around 30V (and a shit ton of short circuit current) don't matter to the terminals whatsoever. But if you leave your 3000€ Sprayer Computer connected, you might end up stressing the electronics beyond their ratings until a capacitor or a polyfuse burns itself in confusion and surprise surprise: it's dead.
It's the same as touching a live 230V wire with crocs on. Doesn't hurt until you take your other hand and touch the sink :))
6:40 for more info on earth as a conductor, look up SWER
Single Wire Earth Return.
Used in some remote areas in Australia and New Zealand, possibly others.
It is funny that kids don't get taught that wind can cause static build up........ This is also not very well known, but, in very dry climates like in my country where we are an arid country this is a major problem and also why ground mats and spikes tend to be buried and driven deeper into the ground as the ground dries out to a very deep depth here making the "earthing" of structures that much more involved. Well done.
Next part of The vídeo please teach us about the absorbing properties of our beloved ground from EMP's, and protection from undesired interferences, thats other plus when using a bottom layer ground at PCB design!!
Unexpected topic but everyone needs to know
Clear explanation super bro 👍👏👍
So nice of you
In Canada we like to live dangerously. My metal toaster has a two wire ungrounded plug.
Thank you for this excellent learning video!
You actually only get chocked because at the generators also have their neutral wires connected to ground. If they didnt there would be no path for the electricity to return and no current would flow.
E.g. When you touch one terminal of a battery there is no circuit formed and no electricity flows to ground.
This is called a « floating » system, since it is normconnected tomground it is floating. This is sometimes used in hospitals or other confined spaces. In a floating system you need 2 ground faults before electricity can flow trough you when you touch the live wire. Adding more security (but mandates that someone follows up on ground faults and detects if the first one happens)
Really great explanation! Thank you
nice video! it's almost midnight and this video is a feast for my tired eyes
Haha happy to hear that :-)
Wish america's grid and electronics were more like that, clean and deterministic, maybe except the 230V
Very very good content, and i apreciate that you are doing experiments, is fun, and a lot of new thinghs to discover in them. You are a very good young teacher for many peoples, and your job is getting better with every new video!👍👍👍
9:14 I had a design which used such a system as a sort of ground. Basically replacing the dirt with a dense source of electrons.
☠️☠️☠️🤓🤓
@@NaveedAhmedpuri Yes it was a deadly weapon. I'm not going into specifics for a reason.
I have some smart home switchable outlets with a 5v dc circuit inside. Depending on the L/N connection, the DC 0 reference is 230V.
Unrelated but I wanted to share that I fixed my keyboard by fixing like 10 broken traces ( I had a rage moment years ago on the poor keyboard) but it's now fixed! Thank you,, jumper wires!
as an electrician yeah you dont mess around with 230-240v AC unless you know what your doing .... if it doesn't kill you it WILL hurt ALOT trust me had many shocks in my life just never been grounded
Fun fact: One of the main hurdles to establishing a Mars colony connecting the Earth wire. The amount of resistance is crazy!
GND is not always ground. With the Shelly devices, GND is placed on the hot cable so that a switch can be used to switch against the hot cable.
The processor then hangs between the hot cable with 230 volts and 226.7 volts. This results in 3.3 volts only at the hot end.
The rectification is a single diode and capacitor.
Protected Earth uses the horizontal line triangle inside a circle. The 0v reference voltage from a battery or power supply will use it without the circle while a half circle is low noise or functional 0v reference ground. Chassis ground uses slanted vertical lines. Additional grounds use an open triangle with an optional letter like A for analog, D for digital, or other symbols like a circle which means points that have the same potential, but may not be ground.
Beautiful video.
Great video, ElectroScott 💥 ! 😉👍
Seeing you playing with metal casings makes me wonder one thing. Nowadays, I've seen tons of products that uses non-standard metal contacts (Like bolts, plates, etc...) to connect multiple parts that need to be easily detachable, i.e. vacuum robots and the charging stations, or cheap bluetooth headphones with tiny metal rods as contact points. In some DIY proyects I have also seen connections made through bolts whose main purpose was just hold two pieces together. How can I measure the electrical properties of such a connection? Like resistance, max current... you know better than me. I think that a video covering such a thing could be interesting!
@greatscottlab
I think there is an error:
The earth and neutral are connected together in the distribution cabin, at the output of the low voltage secondary, not in the house, that's how it works in Italy.
In this way the RCD can trip even with leakage towards the neutral. Because there will be a potential drop in the neutral wire on the way from the cabin to the house, relative to the ground.
To verify this, test measure the voltage between neutral and earth in any outlet. It is usually around 5V but increases proportionally to the loads. Because this also increases the drop on the neutral wire from the cabin to the house.
There are different types of "grounding systems" in use around the world. Here in the US (and Canada) neutral and ground actually are connected in the house's main service panel. From the transformer to the house there is not a dedicated ground wire, only a neutral wire. This neutral is grounded at the transformer as well as each house. This is called a TN-C-S system.
A TN-S system like you describe being used in Italy is AFAIK what most of the civilized world usually uses. Some countries (like the UK) could have a different setup depending on the specific install.
So in case there is no rcb or what is that (is it the same as phi relay?) the reason why safety works is because when electricity go out through metal parts, it creates big short and from aperage output the disconnectors shut down the electricity?
Because I also thought its not only this, but that grounding the outside metal parts create a "better" short through the earth/ground than through me, so deadly current would flow there and not that much through me when I myself touch it. So I think its not only that the electricity goes off and thus safe, but because lower resistance path through grounding when error occurs so even though there is maybe a path through me as I touch it, but its of higher resistance than the probe deep in ground...
I also know that ground reference potential can actually do differ is distance is high enough - what I am not sure when this kicks in though. Like I can choose to put the probe right below the room (because floor gets replaced there soon) where key electronics would maybe benefit it or at outside. I don't think though there is much of a difference.
Oh and please explain what the hell happens when some in some houses I hear they at the incoming box of electricity someone connected the neutral and ground wires - I think its mistake, but still some people do this and I really wonder what the real effects would be of putting the incoming neutral together with the internal ground wire... In theory it means that if 230V goes to the grounded surfaces, then neutral becomes of same potential as the live wire - also as a side effect for half the street or so. This way touching neutral is bad for your health as it would have a huge voltage. Then again however this way potential difference between live and neutral would disappear / shrink and hopefully still the current finds lesser resistance through the netural of the system than through my body if I touch the metal parts of bad objects.
In this sense according to what I think in theory this "bad practice" is actually not that awful as one might think, but still very bad - but mostly because of hazarding the grid power not because of hazarding touching metal parts where the mains live touch someway.
Thank you for Explaining not my questions are cleared ❤
In my parents house in the 90's we had one water pipe that sometimes gave you a bit of a zap. It was an outside tap. So i wrapped copper around a half meter mild steel rod, drilled a hole in the concrete to expose soil, and drive that rod into the soil with the back end of an axe. Other end of the wire I wrapped around the copper water pipe for about 10cm, then welded it with lead and a torche with way to much flux. It worked.
Come to think of it now.... that was maybe not the correct fix. It is only hiding a bigger problem somewhere. I was 15 when i came up that that idea.
Great one Scott! You should probably make some telsa coil drivers, ZVS circuits etc. High voltage circuits
thank you.
Good topic my friend 👍👍🤝
Holy cow! I wanted somebody to do a video like this. You read my mind mah dude!
Very nice explanation 😁👏👏👏👍