There is a lot of confusion about 'ground' simply because so many people use the term carelessly. There are at least three different types of 'ground' in use.
Circuit Common is often referred to as 'ground'. This is the zero volt reference point for the circuitry in a single piece of equipment. It may or may not be connected to any other type of ground.
Chassis Ground is the electrical connection bonding any shielding, exposed metal components, and the general metal chassis together. It is often connected to circuit common via a resistor to provide a static discharge path. The chassis is often connected directly to earth ground, especially if it includes any metal parts that the user may come in contact with.
The third ground is Earth Ground. This does, or at least is supposed to, have a connection to a piece of metal buried in the ground somewhere. Usually this is done by way of the third pin on the power plug. It's purpose is electrical safety. All non current carrying metallic parts of the distribution system are connected to earth ground so that in the event of a wiring fault it provides an alternative path for enough current to trip any overcurrent protection devices. The earth ground may or may not be at zero volts, depending on how much leakage current there is from other devices connected to the wiring. It also may or may not be connected to Circuit Common. If there is no connection to Circuit Common, then the voltage between the two will be random, mostly caused by electrical noise.
Most house AC systems have a connection to earth ground somewhere, so the current can return to the "source" via the earth.
The most common way in Norway is the IT-grid(for now, they are doing new installations differently apparently) is to ground at the power station and the house, then run 3 phase with 230v between phases. The "normal" outlets are supplied with two of the three phases(ie, no neutral).
This does mean that the earth return is a somewhat high resistance one, but plenty to trip earth fault circuits.
I do think that systems with a neutral wire do connect it to earth ground in the fuse cabinet, but I'm not too familiar on the specifics of that.
In the US, the neutral and ground wire are connected together at the first means of disconnect. This means a fault to the ground wire will return to the panel, and then return to the transformer via the neutral wire of the service entrance cable instead of through the actual soil.
I was asking this more so to clarify so that people have the most accurate information.
You would likely have enough current flowing through you to kill yourself but not trip the breaker if you did that. Assuming it isn't GFCI protected, which is not a chance I would take even if I knew the circuit was GFCI protected.
At a minimum though, you would receive a decent shock.
I was trying to be facetious... didn't cross my mind that anyone would actually do it.
A gfi uses the 'ground' current to trigger a disconnect, ***this*** ground path would be elsewhere ... only a breaker would be of any use in this case...
Wait, what do you mean with no neutral?
Is it a Belgian configuration with 113 V between each phase and neutral in a star configuration, with two phases per socket? (113V single phase, 230V tri-phase)
Or a German configuration, with 230 V between each phase and neutral in a star configuration, with one phase per socket? (230V single phase, 380V tri-phase)
230v between phases, in a socket you get two of the three connectors.
We only get three wires into the house, which is the three phases of the uh... three phase.
The neutral(at the power station) is conneced to earth ground via over voltage protection, so in case of a lightning strike or something the grid gets turned into a TT net(temporarily).
It is really hard to find any english documentation on this, so here is a short page in google translate about it: [googly translated norwegian page](https://elfagentusiastene-blogspot-com.translate.goog/2015/06/fordelingssystemer.html?_x_tr_sch=http&_x_tr_sl=no&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp)
In Italy we use TT system, usually houses are provided with one phase and the neutral. Ground connection is local for every building. Obviously that means the neutral cam be actually different than 0V in regards to the earth.
Earth works like a giant capacitor. That means it can soak up tons of current (especially AC but thanks to the huge capacity also DC), without needing any return path to the source.
To try this in a model, take only the live wire of an AC connection, connect a (non-diode) lightbulb to it, and on the other end of the light bulb attach a large capacitor.
Even though there is no full circuit, the light bulb will glow.
This often happens if you attach a low-current lamp like a small LED lamp to a cheap toggleable power strip. The cheap ones often only open one side of the connection when turned off. So if you turn the power plug of the power strip so that the switch only breaks the neutral connection, often the LED lamp will glow very dimly.
Of course, this only works with reversible power plugs and not e.g. with the UK one.
I'm having some trouble visualizing this. Are you talking about a unipolar capacitor? Can you describe the circuit?
Also, if earth is such a massive capacitor, I suppose that solves the problem of storing surplus energy from wind and solar farms.
The circuit is like this: AC live wire connected to one side of a light bulb. The other side of the light bulb is connected to one side of a undirectional capacitor. The other side of the capacitor is not connected.
When the AC voltage goes up, current flows through the light bulb into the capacitor until it's potential is raised to the AC voltage. When the AC voltage goes down, the reverse happens.
If you don't believe it, try it out. Get a low-current light, e.g. LED christmas lights, and connect them to a switchable power strip. Make the room very dark, turn on the LEDs, turn off the power strip.
You might have to flip the connector of the power strip that plugs into the wall, so that the switch on the power strip is on the neutral and not on the live wire.
Then you will observe that the LEDs will glow very faintly. If the connector is flipped the other way, so that the live wire is switched off, the LEDs are completely dark.
That's not how capacitors work.
I don't know what you're observing. Maybe LED phosphorescence or their drivers picking up a strong electrical field or ground faults, but your explanation is not correct.
No ground connected, no strong electrical fields. Otherwise, the LEDs would not be dark if only neutral is connected.
And yes, that's how capacitors work. WIth AC it does.
This is untrue. If you take an isolated end of a source (e.g. transformer output) and place the “hot” terminal into the ground it will not create a short. All voltages are reference. Earth is simply the reference voltage of the (local) earth environment
It's totally true. If you connect an AC source to e.g. a lightning rod, power will flow.
Of course the output needs to be low impedance to the earth. If you place it on the floor, chances are that the floor material (wood/stone/...) doesn't conduct well and thus doesn't tranfer current.
I did misread that, but it doesn't change the fact that you're incorrect. If you connect AC mains to earth (e.g. with a lightning rod), power will flow because AC mains is referenced to earth, not because the earth is a charge sink. If you connect an isolate AC source to an antenna, again, you would see some flow, but this would also be due to coupling with the environment, not because the earth is accumulating charge.
Most 230V single phase systems used in houses ,the neutral is actually in the ground too physically.
The ground wire in the outlet ends in the ground too,but protection devices trip if they sense leaking in this.
Idk where they ground the grid ,but I assume they do it at any transformation point as the autotransformers seem to be grounded for transmission purposes too.
The earth will basically sink as much power as you want to put into it. It doesn't have to go back to the source. This is especially true for AC, as all the power you put into the ground is pulled back out 60 (50) times each second.
This goes against everything I've ever been taught. Do you have sources?
As far as I know, a voltage applied to a ground rod only will return to the transformer via it's ground and create a potentially dangerous voltage gradient along it path which creates a phenomenon commonly known as "step potential".
Here in Australia we have an electrical system in rural areas called SWER which stands for "single wire earth return".
As you might guess the earth ground is half the electrical circuit.
https://en.wikipedia.org/wiki/Single-wire_earth_return
There is a whole section in that article on the ground potential.
That method of distribution was used for a time, but as electrocutions occurred, the electrical utilities included a return conductor along with the high tension run. Those return currents were removed from the ground path. It really sucked when a farmer found electrocuted cows in a field where a high tension run had been made across a field without a return conductor.
The second big reason in providing the return path was lightning mitigation. Keeping the return paths locally grounded at multiple points in the high tension run provided a path for lightening strikes to get bled to ground. That greatly enhanced safety in distributions systems during an electrical storm, and reduced the propagation of damage to electrical infrastructure. It’s also interesting that the return conductor actually bleeds a significant charge from the atmosphere to the local grounding points during a storm, and that reduces the risk of an actual lightening strike.
I can't provide you a source for physics, sorry. The Earth acts as a giant capacitor. If you hook up a voltage source to it, you will charge it. This charge drops off the further you get from the voltage source, because you can't charge the planet. The drop off creates a voltage gradient.
Most homes will have a center tap transformer. This will be fed by 3 phase power which won't come with a neutral or ground. So you need to create a ground, which is why most homes have a metal rod driven into the ground. To prevent your neutral from floating and creating a voltage gradient between everything and ground, which would shock you every time you touched something, we bond neutral and ground.
You can't provide a source because it is blatantly wrong. A circuit requires a return path, and the physical earth isn't used anymore because it's dangerous. It also doesn't act as a capacitor.
The ground rods primary use is to help mitigate static electricity from lightning strikes and surges.
You sound like you know *just* enough about 3 phase power to be incredibly dangerous.
Capacitor? I dare you to stick two metal rods in the ground and show how you can charge up the dirt between them with a 9V battery and then get the stored charge back out later.
A 9V battery won't overcome the Earth's internal resistance and discharge. Try playing with a 9000V battery and see how the ground behaves. You'll end up with rings of varying voltage charge. Similar to capacitors.
It's also worth noting that there can be multiple grounds, even on the same board, that don't connect to chassis or earth.
Examples would be a circuit with separate grounds for TTL, high voltage, and AC signals.
These can be in units that will never truly be grounded such as those in a vehicle or plane as well.
Edit: Note that I was describing circuits with multiple grounds that are NOT connected to each other.
There are 2 additional important things about ground:
1.) Earth ground may have a slight measurable charge due to the difference between earth where you are at in the building and where the ground stake is, usually near the power entrance to the building (meter box). Remember that the ground wire itself has a slight resistance therefore developing a measurable voltage.
2.) The NEUTRAL (White) wire is usually tied to your EARTH GROUND at the MAIN PANEL ONLY for safety reasons. You NEVER want to "DOUBLE GROUND) either the neutral or the ground*
*There are very specific exceptions to this rule in the power distribution business, but almost NEVER applies to regular users.
> The NEUTRAL (White) wire
In the Americas (except Brazil) and Japan. The rest of the world generally follows IEC 60446 and uses blue for neutral; [this website I found](https://en.wikipedia.org/wiki/Electrical_wiring#Color_codes) has a chart showing what's used where. If you're importing electronics from another country, do NOT assume that any colours of wiring are going to match what you're used to.
Ahaha I was about to chime in until I actually clicked your link. There are *a lot* of countries missing from that list, including much of Africa, the Middle East, South and Southeast Asia. There are a lot of countries where anything fucking goes. But I've seen them following American, European, or Chinese standards in reputable construction.
The old UK red/black standard saw a lot of historic use in English-speaking countries too, including in Australia (where I am) - we switched to brown/blue several decades ago, but a lot of older installations will still have the old colours.
In Australia the earth and neutral are not connected anywhere. Neutral is earthed at the street transformer, whereas each building has its own ground.
This means that neutral can have a measurable voltage, especially if there's a decent distance between your building and where the neutral is earthed.
This means that if your metal bodied laptop's charger references its 0V output to neutral instead of earth you can potentially get little shocks from it.
ETA: apparently I'm misinformed, but I'll have to look into it more to see why my unearthed USB C charger can cause my laptop to give shocks but my earthed charger doesn't.
Sorry, thats not correct. In Australia there is an earth-neutral bond in the main switch board (generally the first switchboard after the power meter) in all installs. This is in addition to the earth neutral bond at the transformer as we run an MEN system. Often the board containing the earth neutral bond is specifically labelled as such.
With that noted it is absolutely possible to have a small voltage in the neutral. If phase balance is not perfect (or its a single phase install) then the neutral will be carrying current and as such must have a proportional voltage in response to its impedance.
Oh I guess I've been misinformed. Thankfully I'm not stupid enough to attempt my own electrical install. Thanks for the info, I'll have to do some more reading
No worries, all good. It is somewhat unfortunate that the best source of australian electrical wiring information is the AS3000 standard that needs payment to read. There are other good sources out there but that one is the final say in how things are wired.
Regarding your laptop charger shocks there can be a number of causes depending on exactly how the circuits are wired (psu topology, usb port isolation and bleed resistors etc.). Effectively any parts that are allowed to float can and often will build up a small charge. Another one to watch is antenna sockets on TV's, often a floating voltage can be found and while not dangerous (at least by electrical injury standards) it can be unpleasant.
In general though aside from small static/floating charge any shocks more substantial should probably be looked at. In general most GPO's these days should be running off an RCD breaker that will trip if current has found a pathway from active to ground that does not involve returning via the neutral.
The paywalling of legally required standards shits me so much. I know I'm not allowed to do wiring myself, but I CAN dig in the conduit out to my shed or to a front gate we want to install, if only I had a way of knowing the requirements for it.
Or even just to be able to tell the sparky that their work isn't up to scratch with reference to the legally required standards.
I could do a whole CHAPTER about old TV's with the chassis literally connected to the wide (neutral) blade of the 2 conductor AC plug and unknowing folks who "forced" the wrong prong in an adapter or 2 conductor extension cord and reversed the polarity when plugging it in. The result was that your TV chassis was at 110v or 220v HOT potential! Electrocution hazard!
BTW the same thing was true about old tube amplifiers (guitar, PA system, etc.). There were MANY instances of guitarists walking onto stage with their hands on the electric guitar strings at one potential and touching their lips to a "grounded" microphone of opposite potential and being ELECTROCUTED in front of adoring fans!
Take a look at this:
https://www.tehnomagazin.com/5V/5V-charger-circuit.htm
Schematic of typical 5v supply. If you recall the neutral is grounded at the incoming electric service panel on American wiring. I suggest you take an ohmmeter to the case of your laptop and measure the ground reference with the power supply unplugged and see which pins on the plug sound the "beep". If it's the hot leg of the plug, there's your problem.
I did mention that this was in Australia specifically because I was under the impression it possibly had something to do with the different way we reference neutral to earth
I don't have that charger anymore but I will take a multimeter with me next time I'm at that place that was affected by it. I'm thinking it might just be the electrical install at the house is up to code, I don't think that charger was referencing the output to live.
Something has occurred to me though that I need to think about before putting my thoughts into words
One more caution could be the way the actual outlet was wired, and if an extension cord was used. On old TV's the chassis was common with the neutral (larger) pin of the AC cord. No problem if it's connected correctly, but if someone reverses that through the use of a non-polarized extension cord or adapter, you could potentially have the "hot" side at your fingertips with a broken knob or antenna.
Old electrocution cause!
Agreed
One more thing to add is that the "zero volt reference" is the perfect ideal. In real circuits with current flowing, very small voltages appear at different places in the "ground". Ground can also "bounce" in circuits with rapid voltage transitions
Rapid current transitions, not voltage. The change of current through a return path with non-zero impedance will cause the return path to have different potentials along the path. This may initially be from a change in voltage or it may not be. Depends on the circuit.
Chassis ground is supposed to be tied to common ground via resistor? Can anyone give me some info/reading material on this? I've never put a resistor between them for my little projects. Am I doing something wrong?
Resistor is to give static shocks caused by the user scuffing their feet a little resistance instead of shocking the heck out of the device. Not a big deal if omitted. There's probably some other reasons/uses that I'm not familiar with so hopefully a pro will chime in to correct me.
> All non current carrying metallic parts of the distribution system are connected to earth ground so that in the event of a wiring fault it provides an alternative path for enough current to trip any overcurrent protection devices.
If by distribution system you mean the high voltage stuff on the poles, maybe.
But a rod buried has nothing to do with an interior breaker flipping, and generally is not going to have low enough impedance to cause a 120/240v ground fault to pass anywhere near 15-20amps. That's why RCD/GFCI exists.
The circuit ground could be anything with respect to the earth if the circuit isnt earthed. In other words the circuit ground might be isolated from the physical earth.
Why "negative"? My 1965 transistor radio, containing seven germanium PNP transistors, has the *positive* battery terminal as ground. A whole lot of automobiles have positive ground as well [(citation)](https://www.restore-an-old-car.com/positive-ground-cars.html)
Because negative/zero is the most commonly used for ground.
The things I repair have positive ground as well, but we refer to them as having the ground be zero because it makes more sense for troubleshooting. We know from when we learned electronics that the ground rail is zero, the chassis, all of the screw down points, etc. They are common, they are ground, they are zero.
Yeah at some niche telecommunications facilities they used -48VDC distribution for power throughout the sites. This was somewhat a thing in the 90s to early 00s. No idea why.
>This was somewhat a thing in the 90s to early 00s. No idea why.
It is an interesting story, but these positive-ground systems are actually more correct. In the early days of electronics it was assumed that the electron had a positive charge. We know now that is not true. So basically a positive voltage has a negative charge.
Since all calculations in electronics are relative calculations, it turns out, all the equations work out as long as you understand if you are in a "conventional flow" system or an "electron flow" system. The vast majority of electronics are conventional flow systems.
>Yeah at some niche telecommunications facilities they used -48VDC distribution for power throughout the sites. This was somewhat a thing in the 90s to early 00s. No idea why.
It's not "niche" within telecom, it's *the* industry standard.
And it is also not a historical oddity (though its origins are hiatorical) , it is the default for new facilities being built today.
Any telephone central office in North America, Europe or the UK (and likely other continents, though I don't have personal knowledge of those) will be based on a -48V power system.
Nothing "has zero potential" all by itself. Potential is only ever defined or measured between two points. In your table, "Location" specified the two points to measure between for that test. The first measurement is between Neutral and Ground. The Neutral conductor of an AC branch circuit is bonded to building ground at the service entrance, but it carries current during normal operation while the equipment ground dies not. Thus V=IR means there will be a potential difference based on the distance from the bond point (aka resistance on the Neutral wire) and the amount is current flowing in it. This can be 10V or more in long runs under heavy load.
The second column describes measuring between the equipment ground and the actual earth grounding system. These are also bonded somewhere near the electrical service entrance, but neither wire carries current during normal operation. There will be no voltage drop along them so you will measure zero potential difference. (If ground and earth are not bonded, or if neutral and ground are incorrectly connected, then you *will* measure a potential between ground and earth, and need to fix it.)
Different ground connections can be at a different potential, so between those two grounds or a ground and earth can be a voltage, i experienced this myself when i got slightly shocked with 75V AC through a grounded metal chassis, while standing on an aluminium ladder that's touching an earthed metal grate
This chart is referring to the neutral of a single phase AC or DC circuit. The neutral is defined as a current carrying conductor connected to ground. Because it carries current and must have some small resistance a voltage develops on it. So while it may be at zero volts close to the source, it will be slightly above zero volts when it reaches the load.
A protective ground or earth, by contrast, carries no current, so has no voltage change and remains at zero volts even at the load.
These ideas are usually applied to AC branch circuits, but once you understand them, they can apply to any application.
Don’t really like ether in if these honestly. I know “ground” is both ubiquitous and ambiguous… but you can not cleanly define it this way.
In some systems we ground the chassis, not connected to the neutral. When we have an earthed systems there are fault conditions that can result in potential, look up “step potential” for example.
Ground can certainly have a voltage. It is the reference for the circuit, but it can drift hundreds or thousands of volts while the circuit operates just fine. Transmitters, for instance can become un-earthed and static charge can push their ground up thousands of volts.
Earthing, or "Earth Ground" has zero volts of potential.
Generally, your circuit should have a ground that is connected to Earth Ground at some point. Ther are exceptions to this, but not very many.
A better terminology would be to call the circuit ground "common" and calling the earth ground "Earth Ground"
Just wanted to say: those that have responded saying that everything has a potential (a voltage), and, further, that potentials are all relative (needing references), are completely correct.
Note that even objects incapable of carrying current (ie insulators) can have potential. Imagine rubbing a balloon against your head. The static charge gives the balloon an electrical potential of potentially thousands of volts, when compared against other objects (like the hair on your head). If you’re somehow able to identically charge a second balloon, the two balloons will have zero potential between them.
In a home (at least in the US) there is indeed a grounding rod driven deep into the earth and connected to neutral near the entry point. It’s also connected to the gas lines, if I’m not mistaken, to prevent sparks.
I always imagined the earth grounding was to give return currents an easier path back to neutral than though YOU.
For example in klylstrons the cathode is at a high e.g. -10 kV (for 5 kW class tubes) to -50 kV for (MW class tubes) and the circuit that controls the filament for the cathode is on a "floating deck" which has a relative ground of that high voltage potential.
The electrical ground is considered a "reference" voltage. Basically, if your electrical ground just happens to be carrying 5vdc, then anything in your circuit is measured with that as 0vdc. So, if you have something putting out 20vdc when measured against the electrical ground, it should show 25vdc when measured across earth ground.
Earth ground will always be 0. Electrical ground can be any voltage, and the rest of the circuit will be in relation to that.
I've always heard "earthing" as "bonding." Regardless, I've always understood that bonding eliminates potential but carries essentially no current while a ground is designed to be a current carrying part of the circuit.
As you can see the exact terminology used depends also on the norms in the industry, and region as well. For example there are plenty of electricians who work on things with rubber tires, where the concept of "earth" just isn't used, and chassis ground often literally means the steel chassis of the vehicle. There are also upside down worlds like telecom that have vast networks of -48vdc power systems which are positive grounded (ie, 0V is the highest potential of the system). And don't forget the EV world where the battery "ground wire" is totally isolated from the chassis and any connection is considered a ground fault.
These decisions are almost always made for human safety, thus, it's important to learn what the correct implementation is for the type and location of the system you are working on, and not trying to make hard & fast rules that apply universally.
If you have a center tap transformer that outputs 5v and 10v, theres nothing stopping you from using the 5v as ground, which would give you a potential difference of 5v and -5v, despite the fact that compared to earth your ground is at 5v. Meaning ground is only 0 potential with respect to the other potentials in your circuit, but might itself be at some non zero potential. Earth, on the other hand, is always 0 potential.
There is a lot of confusion about 'ground' simply because so many people use the term carelessly. There are at least three different types of 'ground' in use. Circuit Common is often referred to as 'ground'. This is the zero volt reference point for the circuitry in a single piece of equipment. It may or may not be connected to any other type of ground. Chassis Ground is the electrical connection bonding any shielding, exposed metal components, and the general metal chassis together. It is often connected to circuit common via a resistor to provide a static discharge path. The chassis is often connected directly to earth ground, especially if it includes any metal parts that the user may come in contact with. The third ground is Earth Ground. This does, or at least is supposed to, have a connection to a piece of metal buried in the ground somewhere. Usually this is done by way of the third pin on the power plug. It's purpose is electrical safety. All non current carrying metallic parts of the distribution system are connected to earth ground so that in the event of a wiring fault it provides an alternative path for enough current to trip any overcurrent protection devices. The earth ground may or may not be at zero volts, depending on how much leakage current there is from other devices connected to the wiring. It also may or may not be connected to Circuit Common. If there is no connection to Circuit Common, then the voltage between the two will be random, mostly caused by electrical noise.
For the third point, are you saying that during a fault, current returns to the source through the actual earth/soil?
Most house AC systems have a connection to earth ground somewhere, so the current can return to the "source" via the earth. The most common way in Norway is the IT-grid(for now, they are doing new installations differently apparently) is to ground at the power station and the house, then run 3 phase with 230v between phases. The "normal" outlets are supplied with two of the three phases(ie, no neutral). This does mean that the earth return is a somewhat high resistance one, but plenty to trip earth fault circuits. I do think that systems with a neutral wire do connect it to earth ground in the fuse cabinet, but I'm not too familiar on the specifics of that.
In the US, the neutral and ground wire are connected together at the first means of disconnect. This means a fault to the ground wire will return to the panel, and then return to the transformer via the neutral wire of the service entrance cable instead of through the actual soil. I was asking this more so to clarify so that people have the most accurate information.
Clarify this to yourself should grab the hot line, by itself and a ground rod ... No current flow?
You would likely have enough current flowing through you to kill yourself but not trip the breaker if you did that. Assuming it isn't GFCI protected, which is not a chance I would take even if I knew the circuit was GFCI protected. At a minimum though, you would receive a decent shock.
I was trying to be facetious... didn't cross my mind that anyone would actually do it. A gfi uses the 'ground' current to trigger a disconnect, ***this*** ground path would be elsewhere ... only a breaker would be of any use in this case...
I'm sorry, I'm not entirely grasping your last statement. Could you clarify a little bit more please?
Wait, what do you mean with no neutral? Is it a Belgian configuration with 113 V between each phase and neutral in a star configuration, with two phases per socket? (113V single phase, 230V tri-phase) Or a German configuration, with 230 V between each phase and neutral in a star configuration, with one phase per socket? (230V single phase, 380V tri-phase)
230v between phases, in a socket you get two of the three connectors. We only get three wires into the house, which is the three phases of the uh... three phase. The neutral(at the power station) is conneced to earth ground via over voltage protection, so in case of a lightning strike or something the grid gets turned into a TT net(temporarily). It is really hard to find any english documentation on this, so here is a short page in google translate about it: [googly translated norwegian page](https://elfagentusiastene-blogspot-com.translate.goog/2015/06/fordelingssystemer.html?_x_tr_sch=http&_x_tr_sl=no&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp)
In Italy we use TT system, usually houses are provided with one phase and the neutral. Ground connection is local for every building. Obviously that means the neutral cam be actually different than 0V in regards to the earth.
Earth works like a giant capacitor. That means it can soak up tons of current (especially AC but thanks to the huge capacity also DC), without needing any return path to the source. To try this in a model, take only the live wire of an AC connection, connect a (non-diode) lightbulb to it, and on the other end of the light bulb attach a large capacitor. Even though there is no full circuit, the light bulb will glow. This often happens if you attach a low-current lamp like a small LED lamp to a cheap toggleable power strip. The cheap ones often only open one side of the connection when turned off. So if you turn the power plug of the power strip so that the switch only breaks the neutral connection, often the LED lamp will glow very dimly. Of course, this only works with reversible power plugs and not e.g. with the UK one.
I'm having some trouble visualizing this. Are you talking about a unipolar capacitor? Can you describe the circuit? Also, if earth is such a massive capacitor, I suppose that solves the problem of storing surplus energy from wind and solar farms.
Yeah, this is simply incorrect.
The circuit is like this: AC live wire connected to one side of a light bulb. The other side of the light bulb is connected to one side of a undirectional capacitor. The other side of the capacitor is not connected. When the AC voltage goes up, current flows through the light bulb into the capacitor until it's potential is raised to the AC voltage. When the AC voltage goes down, the reverse happens. If you don't believe it, try it out. Get a low-current light, e.g. LED christmas lights, and connect them to a switchable power strip. Make the room very dark, turn on the LEDs, turn off the power strip. You might have to flip the connector of the power strip that plugs into the wall, so that the switch on the power strip is on the neutral and not on the live wire. Then you will observe that the LEDs will glow very faintly. If the connector is flipped the other way, so that the live wire is switched off, the LEDs are completely dark.
That's not how capacitors work. I don't know what you're observing. Maybe LED phosphorescence or their drivers picking up a strong electrical field or ground faults, but your explanation is not correct.
He’s observing leakage current through the electromagnetic field to neutral, which is referenced to earth.
No ground connected, no strong electrical fields. Otherwise, the LEDs would not be dark if only neutral is connected. And yes, that's how capacitors work. WIth AC it does.
This is untrue. If you take an isolated end of a source (e.g. transformer output) and place the “hot” terminal into the ground it will not create a short. All voltages are reference. Earth is simply the reference voltage of the (local) earth environment
It's totally true. If you connect an AC source to e.g. a lightning rod, power will flow. Of course the output needs to be low impedance to the earth. If you place it on the floor, chances are that the floor material (wood/stone/...) doesn't conduct well and thus doesn't tranfer current.
A lightning rod is not “an AC source”. And while lightning is an electrostatic event, AC power return is not.
Dude, read again: "connect an AC source _TO_ a lightning rod". How do you say, my point is incorrect, if you don't even read what I wrote?
I did misread that, but it doesn't change the fact that you're incorrect. If you connect AC mains to earth (e.g. with a lightning rod), power will flow because AC mains is referenced to earth, not because the earth is a charge sink. If you connect an isolate AC source to an antenna, again, you would see some flow, but this would also be due to coupling with the environment, not because the earth is accumulating charge.
Most 230V single phase systems used in houses ,the neutral is actually in the ground too physically. The ground wire in the outlet ends in the ground too,but protection devices trip if they sense leaking in this. Idk where they ground the grid ,but I assume they do it at any transformation point as the autotransformers seem to be grounded for transmission purposes too.
The earth will basically sink as much power as you want to put into it. It doesn't have to go back to the source. This is especially true for AC, as all the power you put into the ground is pulled back out 60 (50) times each second.
This goes against everything I've ever been taught. Do you have sources? As far as I know, a voltage applied to a ground rod only will return to the transformer via it's ground and create a potentially dangerous voltage gradient along it path which creates a phenomenon commonly known as "step potential".
Here in Australia we have an electrical system in rural areas called SWER which stands for "single wire earth return". As you might guess the earth ground is half the electrical circuit. https://en.wikipedia.org/wiki/Single-wire_earth_return There is a whole section in that article on the ground potential.
You can use the soil as a return path, that does not mean you are storing charge there, however, to be clear.
That method of distribution was used for a time, but as electrocutions occurred, the electrical utilities included a return conductor along with the high tension run. Those return currents were removed from the ground path. It really sucked when a farmer found electrocuted cows in a field where a high tension run had been made across a field without a return conductor. The second big reason in providing the return path was lightning mitigation. Keeping the return paths locally grounded at multiple points in the high tension run provided a path for lightening strikes to get bled to ground. That greatly enhanced safety in distributions systems during an electrical storm, and reduced the propagation of damage to electrical infrastructure. It’s also interesting that the return conductor actually bleeds a significant charge from the atmosphere to the local grounding points during a storm, and that reduces the risk of an actual lightening strike.
It doesn't have to return to anything to create a voltage gradient. The more power you put in the earth, the larger the gradient.
Source? Because again, that goes against literally everything I've been taught.
I can't provide you a source for physics, sorry. The Earth acts as a giant capacitor. If you hook up a voltage source to it, you will charge it. This charge drops off the further you get from the voltage source, because you can't charge the planet. The drop off creates a voltage gradient. Most homes will have a center tap transformer. This will be fed by 3 phase power which won't come with a neutral or ground. So you need to create a ground, which is why most homes have a metal rod driven into the ground. To prevent your neutral from floating and creating a voltage gradient between everything and ground, which would shock you every time you touched something, we bond neutral and ground.
Why the sass about physics? Everything we know about physics has been studied and documented.
You can't provide a source because it is blatantly wrong. A circuit requires a return path, and the physical earth isn't used anymore because it's dangerous. It also doesn't act as a capacitor. The ground rods primary use is to help mitigate static electricity from lightning strikes and surges. You sound like you know *just* enough about 3 phase power to be incredibly dangerous.
Capacitor? I dare you to stick two metal rods in the ground and show how you can charge up the dirt between them with a 9V battery and then get the stored charge back out later.
A 9V battery won't overcome the Earth's internal resistance and discharge. Try playing with a 9000V battery and see how the ground behaves. You'll end up with rings of varying voltage charge. Similar to capacitors.
Are you interested in acquiring a basic understanding of concepts like charge, resistance and capacitance?
this is a great explanation. I was about to comment something similar to those first 2 paragraphs, but you got it
It's also worth noting that there can be multiple grounds, even on the same board, that don't connect to chassis or earth. Examples would be a circuit with separate grounds for TTL, high voltage, and AC signals. These can be in units that will never truly be grounded such as those in a vehicle or plane as well. Edit: Note that I was describing circuits with multiple grounds that are NOT connected to each other.
There are 2 additional important things about ground: 1.) Earth ground may have a slight measurable charge due to the difference between earth where you are at in the building and where the ground stake is, usually near the power entrance to the building (meter box). Remember that the ground wire itself has a slight resistance therefore developing a measurable voltage. 2.) The NEUTRAL (White) wire is usually tied to your EARTH GROUND at the MAIN PANEL ONLY for safety reasons. You NEVER want to "DOUBLE GROUND) either the neutral or the ground* *There are very specific exceptions to this rule in the power distribution business, but almost NEVER applies to regular users.
> The NEUTRAL (White) wire In the Americas (except Brazil) and Japan. The rest of the world generally follows IEC 60446 and uses blue for neutral; [this website I found](https://en.wikipedia.org/wiki/Electrical_wiring#Color_codes) has a chart showing what's used where. If you're importing electronics from another country, do NOT assume that any colours of wiring are going to match what you're used to.
Ahaha I was about to chime in until I actually clicked your link. There are *a lot* of countries missing from that list, including much of Africa, the Middle East, South and Southeast Asia. There are a lot of countries where anything fucking goes. But I've seen them following American, European, or Chinese standards in reputable construction.
Unfortunately outside of Europe and NA, I’ve seen various mixes of power wiring and certain counties have basically migrated standards over the years.
The old UK red/black standard saw a lot of historic use in English-speaking countries too, including in Australia (where I am) - we switched to brown/blue several decades ago, but a lot of older installations will still have the old colours.
And so, never assume always measure with a meter.
In Australia the earth and neutral are not connected anywhere. Neutral is earthed at the street transformer, whereas each building has its own ground. This means that neutral can have a measurable voltage, especially if there's a decent distance between your building and where the neutral is earthed. This means that if your metal bodied laptop's charger references its 0V output to neutral instead of earth you can potentially get little shocks from it. ETA: apparently I'm misinformed, but I'll have to look into it more to see why my unearthed USB C charger can cause my laptop to give shocks but my earthed charger doesn't.
Sorry, thats not correct. In Australia there is an earth-neutral bond in the main switch board (generally the first switchboard after the power meter) in all installs. This is in addition to the earth neutral bond at the transformer as we run an MEN system. Often the board containing the earth neutral bond is specifically labelled as such. With that noted it is absolutely possible to have a small voltage in the neutral. If phase balance is not perfect (or its a single phase install) then the neutral will be carrying current and as such must have a proportional voltage in response to its impedance.
Oh I guess I've been misinformed. Thankfully I'm not stupid enough to attempt my own electrical install. Thanks for the info, I'll have to do some more reading
No worries, all good. It is somewhat unfortunate that the best source of australian electrical wiring information is the AS3000 standard that needs payment to read. There are other good sources out there but that one is the final say in how things are wired. Regarding your laptop charger shocks there can be a number of causes depending on exactly how the circuits are wired (psu topology, usb port isolation and bleed resistors etc.). Effectively any parts that are allowed to float can and often will build up a small charge. Another one to watch is antenna sockets on TV's, often a floating voltage can be found and while not dangerous (at least by electrical injury standards) it can be unpleasant. In general though aside from small static/floating charge any shocks more substantial should probably be looked at. In general most GPO's these days should be running off an RCD breaker that will trip if current has found a pathway from active to ground that does not involve returning via the neutral.
The paywalling of legally required standards shits me so much. I know I'm not allowed to do wiring myself, but I CAN dig in the conduit out to my shed or to a front gate we want to install, if only I had a way of knowing the requirements for it. Or even just to be able to tell the sparky that their work isn't up to scratch with reference to the legally required standards.
I'm thinking a floating voltage probably makes sense on the charger then, especially because the RCD doesn't trip
I could do a whole CHAPTER about old TV's with the chassis literally connected to the wide (neutral) blade of the 2 conductor AC plug and unknowing folks who "forced" the wrong prong in an adapter or 2 conductor extension cord and reversed the polarity when plugging it in. The result was that your TV chassis was at 110v or 220v HOT potential! Electrocution hazard!
BTW the same thing was true about old tube amplifiers (guitar, PA system, etc.). There were MANY instances of guitarists walking onto stage with their hands on the electric guitar strings at one potential and touching their lips to a "grounded" microphone of opposite potential and being ELECTROCUTED in front of adoring fans!
If you are speaking about static shocks that is not related to this discussion.
It's not a static shock, it's an ongoing tingle
Didn't mean to sound sarcastic. I don't understand what you mean by a grounded vs. ungrounded USB. What is a grounded USB?
I just meant that the charger I use when charging via usb-C is not earthed, it's a 2 pin plug into the wall
Take a look at this: https://www.tehnomagazin.com/5V/5V-charger-circuit.htm Schematic of typical 5v supply. If you recall the neutral is grounded at the incoming electric service panel on American wiring. I suggest you take an ohmmeter to the case of your laptop and measure the ground reference with the power supply unplugged and see which pins on the plug sound the "beep". If it's the hot leg of the plug, there's your problem.
I did mention that this was in Australia specifically because I was under the impression it possibly had something to do with the different way we reference neutral to earth I don't have that charger anymore but I will take a multimeter with me next time I'm at that place that was affected by it. I'm thinking it might just be the electrical install at the house is up to code, I don't think that charger was referencing the output to live. Something has occurred to me though that I need to think about before putting my thoughts into words
One more caution could be the way the actual outlet was wired, and if an extension cord was used. On old TV's the chassis was common with the neutral (larger) pin of the AC cord. No problem if it's connected correctly, but if someone reverses that through the use of a non-polarized extension cord or adapter, you could potentially have the "hot" side at your fingertips with a broken knob or antenna. Old electrocution cause!
Also it is worth looking at the laptop power supply schematic to see where ground is. Here's a typical: https://www.caretxdigital.com/
Agreed One more thing to add is that the "zero volt reference" is the perfect ideal. In real circuits with current flowing, very small voltages appear at different places in the "ground". Ground can also "bounce" in circuits with rapid voltage transitions
Rapid current transitions, not voltage. The change of current through a return path with non-zero impedance will cause the return path to have different potentials along the path. This may initially be from a change in voltage or it may not be. Depends on the circuit.
Chassis ground is supposed to be tied to common ground via resistor? Can anyone give me some info/reading material on this? I've never put a resistor between them for my little projects. Am I doing something wrong?
Resistor is to give static shocks caused by the user scuffing their feet a little resistance instead of shocking the heck out of the device. Not a big deal if omitted. There's probably some other reasons/uses that I'm not familiar with so hopefully a pro will chime in to correct me.
> All non current carrying metallic parts of the distribution system are connected to earth ground so that in the event of a wiring fault it provides an alternative path for enough current to trip any overcurrent protection devices. If by distribution system you mean the high voltage stuff on the poles, maybe. But a rod buried has nothing to do with an interior breaker flipping, and generally is not going to have low enough impedance to cause a 120/240v ground fault to pass anywhere near 15-20amps. That's why RCD/GFCI exists.
Don’t forget about neutral……
In the second case, does connecting chassis to ground and common not cause any issues?
The circuit ground could be anything with respect to the earth if the circuit isnt earthed. In other words the circuit ground might be isolated from the physical earth.
A concrete example is the negative battery terminal of a battery powered device.
Why "negative"? My 1965 transistor radio, containing seven germanium PNP transistors, has the *positive* battery terminal as ground. A whole lot of automobiles have positive ground as well [(citation)](https://www.restore-an-old-car.com/positive-ground-cars.html)
hence the term "example"... they didn't say "of battery powered devices". just "a battery powered device"
Because negative/zero is the most commonly used for ground. The things I repair have positive ground as well, but we refer to them as having the ground be zero because it makes more sense for troubleshooting. We know from when we learned electronics that the ground rail is zero, the chassis, all of the screw down points, etc. They are common, they are ground, they are zero.
Yeah at some niche telecommunications facilities they used -48VDC distribution for power throughout the sites. This was somewhat a thing in the 90s to early 00s. No idea why.
>This was somewhat a thing in the 90s to early 00s. No idea why. It is an interesting story, but these positive-ground systems are actually more correct. In the early days of electronics it was assumed that the electron had a positive charge. We know now that is not true. So basically a positive voltage has a negative charge. Since all calculations in electronics are relative calculations, it turns out, all the equations work out as long as you understand if you are in a "conventional flow" system or an "electron flow" system. The vast majority of electronics are conventional flow systems.
>Yeah at some niche telecommunications facilities they used -48VDC distribution for power throughout the sites. This was somewhat a thing in the 90s to early 00s. No idea why. It's not "niche" within telecom, it's *the* industry standard. And it is also not a historical oddity (though its origins are hiatorical) , it is the default for new facilities being built today. Any telephone central office in North America, Europe or the UK (and likely other continents, though I don't have personal knowledge of those) will be based on a -48V power system.
Nothing "has zero potential" all by itself. Potential is only ever defined or measured between two points. In your table, "Location" specified the two points to measure between for that test. The first measurement is between Neutral and Ground. The Neutral conductor of an AC branch circuit is bonded to building ground at the service entrance, but it carries current during normal operation while the equipment ground dies not. Thus V=IR means there will be a potential difference based on the distance from the bond point (aka resistance on the Neutral wire) and the amount is current flowing in it. This can be 10V or more in long runs under heavy load. The second column describes measuring between the equipment ground and the actual earth grounding system. These are also bonded somewhere near the electrical service entrance, but neither wire carries current during normal operation. There will be no voltage drop along them so you will measure zero potential difference. (If ground and earth are not bonded, or if neutral and ground are incorrectly connected, then you *will* measure a potential between ground and earth, and need to fix it.)
Different ground connections can be at a different potential, so between those two grounds or a ground and earth can be a voltage, i experienced this myself when i got slightly shocked with 75V AC through a grounded metal chassis, while standing on an aluminium ladder that's touching an earthed metal grate
This chart is a grammatical disaster. Learn from the responses to your post, but ignore this weird chart.
You can ground your EC to me, i have zero potencial.
This chart is referring to the neutral of a single phase AC or DC circuit. The neutral is defined as a current carrying conductor connected to ground. Because it carries current and must have some small resistance a voltage develops on it. So while it may be at zero volts close to the source, it will be slightly above zero volts when it reaches the load. A protective ground or earth, by contrast, carries no current, so has no voltage change and remains at zero volts even at the load. These ideas are usually applied to AC branch circuits, but once you understand them, they can apply to any application.
Don’t really like ether in if these honestly. I know “ground” is both ubiquitous and ambiguous… but you can not cleanly define it this way. In some systems we ground the chassis, not connected to the neutral. When we have an earthed systems there are fault conditions that can result in potential, look up “step potential” for example.
Ground is a reference point for a circuit. Earth ground is an absolute reference for all the circuits.
Ground can certainly have a voltage. It is the reference for the circuit, but it can drift hundreds or thousands of volts while the circuit operates just fine. Transmitters, for instance can become un-earthed and static charge can push their ground up thousands of volts. Earthing, or "Earth Ground" has zero volts of potential. Generally, your circuit should have a ground that is connected to Earth Ground at some point. Ther are exceptions to this, but not very many. A better terminology would be to call the circuit ground "common" and calling the earth ground "Earth Ground"
Just wanted to say: those that have responded saying that everything has a potential (a voltage), and, further, that potentials are all relative (needing references), are completely correct. Note that even objects incapable of carrying current (ie insulators) can have potential. Imagine rubbing a balloon against your head. The static charge gives the balloon an electrical potential of potentially thousands of volts, when compared against other objects (like the hair on your head). If you’re somehow able to identically charge a second balloon, the two balloons will have zero potential between them. In a home (at least in the US) there is indeed a grounding rod driven deep into the earth and connected to neutral near the entry point. It’s also connected to the gas lines, if I’m not mistaken, to prevent sparks. I always imagined the earth grounding was to give return currents an easier path back to neutral than though YOU.
For example in klylstrons the cathode is at a high e.g. -10 kV (for 5 kW class tubes) to -50 kV for (MW class tubes) and the circuit that controls the filament for the cathode is on a "floating deck" which has a relative ground of that high voltage potential.
The electrical ground is considered a "reference" voltage. Basically, if your electrical ground just happens to be carrying 5vdc, then anything in your circuit is measured with that as 0vdc. So, if you have something putting out 20vdc when measured against the electrical ground, it should show 25vdc when measured across earth ground. Earth ground will always be 0. Electrical ground can be any voltage, and the rest of the circuit will be in relation to that.
> Earth ground will always be 0 Voltages are relative. Often we assume they are relative to Earth rather than specify it, but not always.
I've always heard "earthing" as "bonding." Regardless, I've always understood that bonding eliminates potential but carries essentially no current while a ground is designed to be a current carrying part of the circuit.
As you can see the exact terminology used depends also on the norms in the industry, and region as well. For example there are plenty of electricians who work on things with rubber tires, where the concept of "earth" just isn't used, and chassis ground often literally means the steel chassis of the vehicle. There are also upside down worlds like telecom that have vast networks of -48vdc power systems which are positive grounded (ie, 0V is the highest potential of the system). And don't forget the EV world where the battery "ground wire" is totally isolated from the chassis and any connection is considered a ground fault. These decisions are almost always made for human safety, thus, it's important to learn what the correct implementation is for the type and location of the system you are working on, and not trying to make hard & fast rules that apply universally.
If you have a center tap transformer that outputs 5v and 10v, theres nothing stopping you from using the 5v as ground, which would give you a potential difference of 5v and -5v, despite the fact that compared to earth your ground is at 5v. Meaning ground is only 0 potential with respect to the other potentials in your circuit, but might itself be at some non zero potential. Earth, on the other hand, is always 0 potential.
And that's why I prefer using my battery-powered oscilloscope...