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Is this different to a short circuit and if so then how? Because some circuit breaker protect from both short circuits and ground fault thanks, so when do u need to protect from them and when don’t you ?

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    \$\begingroup\$ Go google RCD or GCFI \$\endgroup\$ – Andy aka Feb 5 at 8:14
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    \$\begingroup\$ @Andyaka Minor typo; GFCI (ground fault circuit interrupter) \$\endgroup\$ – Caius Jard Feb 5 at 10:06
  • \$\begingroup\$ Don't forget Arc fault interruptors to round out your research. Home Improvement.SE is a good resource for GFCI and AFCI questions (search, we have plenty of questions about them). \$\endgroup\$ – JPhi1618 Feb 5 at 16:19
  • \$\begingroup\$ @Andyaka mentioned this above, but worth noting explicitly: in the UK (and I'm not sure where else) the GFCI is called an "RCD" or "Residual Current Detector". That may be a better name; what it detects is current that "comes out" from the outlet but doesn't "go back in", i.e. "residual current". The current probably does eventually get to the ground one way or another, but the "fault" is any current path going "elsewhere". This is an important fault because "elsewhere" could involve your body, and you can be killed by a small current that won't trip the breaker fast enough (or at all.) \$\endgroup\$ – Glenn Willen 2 days ago
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A short circuit means the circuit is shorted so too much current flows. More current than the wires and switches etc. can handle. If that current continues to flow, there is a risk of overheating and fire.

Read here about Ground Fault Protection.

The ground is there to protect people from electric shock. Your washing machine doesn't care if its metal case has an AC voltage of 120 or 240 V relative to ground. It will still work! But if you touch it then you would get an electric shock. That we want to prevent and that is why grounding is needed. The metal case of your washing machine should be grounded, so connected to ground. That ground is often a metal pin that literally sticks into the earth. It must not have any voltage on it so that it is safe to touch.

Now if your washing machine develops a fault and it makes a connection between the mains and ground then current "escapes" via the ground. The Ground Fault Protection detects that and switches everything off for your safety.

The circuit breakers that protect against short circuits and grounding faults just combine the two functions in one device. You should always have both protections installed in any installation for added safety. It does not matter if short circuit protection and ground fault protection are in one device or separate devices connected in series.

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    \$\begingroup\$ I'm amused that we both picked on the washing machine, virtually simultaneously \$\endgroup\$ – Caius Jard Feb 5 at 8:46
  • \$\begingroup\$ @CaiusJard That is indeed amusing. When I have a ground fault at my home, the first suspect is usually the washing machine. \$\endgroup\$ – Bimpelrekkie Feb 5 at 9:34
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    \$\begingroup\$ I had a ground fault in a cooktop once, soup had boiled over filled and the metal box below the control knobs. this blew the 60A ceramic supply fuse, plunging the house into darkness. the 15A re-wirable cooktop fuse was unaffected. (Australia) \$\endgroup\$ – Jasen Feb 5 at 9:51
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It's where electrical current in a circuit (that has a ground or earth provision) leaks away to ground rather than going where it is supposed to go. It is different from a short circuit, which is a failure that causes a larger than expected amount of current to flow round the circuit

In the context of home electrical wiring, because it's what most people are familiar with, that has a Live, Neutral and Ground conductor set, if you wired the Live and Ground circuits directly together you would be causing a ground fault because current is leaving the circuit and leaking away to ground. If you wired the Live and Neutral directly together you would likely be causing a short circuit - literally a shortcut for a large amount of current to take

In a real live appliance, say a washing machine, the metal case is connected to ground for safety reasons. Internally, where the single supply cord splits out into its 3 component cables if the live cable rubbed on the case and wore through so that the conductor was exposed and touching the metal of the case, the case becomes live and a ground fault occurs because current is leaking from live into the case and the case is connected to ground. If the case were not connected to ground, then the whole case would become live and wait for you to touch it, so that you connect it to ground (literally the floor you're standing on) delivering an electric shock

If the circuit the washer is plugged into has a ground fault protection device (a device that measures current in on the live and current out on the neutral) that detects an imbalance in the in and out flows on the live and neutral cables, it assumes that current is leaking to ground and disconnects the circuit.

The circuit may also have a short circuit/overload protection, that measures the total amount of current flowing and disconnects above a certain value. These aren't reliable in detecting ground faults because it may be that not enough current is leaking away to cause an overload. Circuit breakers that protect against overload are primarily intended to stop the cable in the wall from catching fire if a short circuit develops in an appliance. A short circuit may be to ground but is more typically between live and neutral - say your washer suffered some problem in the motor where a burnt out connection was causing a large amount of current to flow- it's a short circuit between live and neutral, and not of interest to the ground fault detection

Ground fault detectors are typically highly sensitive, are specified to act within a certain time eg 30ms, and intended to help humans stay alive when they become the connection between live and ground. Short circuit protections are quite insensitive and will frequently allow brief flows of current well over their rates tripping current threshold

It may also be worth noting that not every appliance has a connection to ground. Most plastic cases appliances these days are referred to as double insulated, and bear a logo of two squares one inside the other. It means the internals are encased in such a way that no external part of the appliance can become live through a fault of the internals. You could still cause a ground fault with one of these devices if you did manage to touch something inside that was live (poking a metal knife into the end of an active hairdryer, or throwing a powered up toaster into a bath of water for example) but a failure of one of these devices is more likely to result in an over-current situation than a current-leak

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Respectfully, Electricity is not trying to go to ground. Electricity flows from the source through the load (appliances etc...) and back to the source. If a ground fault(leak) occurs, the flow of electricity is taking a path other than the intended path as in your washing machine frame. When we install an equipment grounding conductor, it runs parallel to the ungrounded and grounded conductors (hot and neutral) and connects to all metal parts of the system likely to become energized and right back to the source thus creating a second path that has low impedance then it's simple math. Voltage divided by very low impedance equals high current flow. This high current efficiently trips the overcurrent device. Lets say you had a 120 volt source that rubbed up against the frame of your washing machine. Lets say the resistance of this connection was 4 milliamps. 120/.004=300 amps. For a split second the overcurrent device would see a load of 300 amps and would trip instantaneously. This is why even the smallest residential breakers have an interrupting rating of 10,000 amps.

Ground rods serve only a few purposes. They help direct lightning, stray voltage or voltage surges to the ground and nothing more. A short circuit on the other hand is when the ungrounded (hot) conductor and the grounded conductor (neutral) come in contact with each other, not rub against a metallic object. When this happens depending on the distance from the source you've essentially removed resistance from the circuit causing the overcurrent device to trip. Note Grounded and grounding are not the same. Grounded is the conductor we intentionally connect to the grounded neutral bar in the panel that carries the unbalanced load back to the source. Grounding conductors only carry current when there is a ground fault condition (leak) like the example above. I hope this helps clear things up a bit.

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https://youtu.be/mpgAVE4UwFw. This is a long video but will explain the concept of grounding to you in enough detail and simply that you should understand how it works after watching.

Essentially David Greer is correct. Current WILL NOT FLOW through a wire unless there is a return path to the source. All the ground wires in your house are connected to the breaker or fuse box and thus directly back to the outlet where the ground fault occured so that current will still flow and the circuit will remain complete. This is intentional. The gist being the return path through the ground to the fuse box is so low impedance that the fuse will blow open and thus disconnect power from the line coming into your home to the outlet itself turning off the outlet and saving your life.

I mean I can't solder a wire to the positive terminal of a battery and then to an LED and then just touch something metal off the negative terminal of the LED and expect the light to turn on. Nope ain't gonna happen unless there is a return path.

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