revisiting the gfci

[DLB]

... GFI will only protect against a ground fault passing through the device .

I'm not sure what you mean by 'ground fault passing through the device.' A Ground Fault is unintended electrical current flowing to ground. Generally, that's return current that should be on neutral but isn't. It has nothing to do with whether or not the ground fault current is flowing through the device. Meaning the ground current may or may not be flowing through the device depending on the nature of the fault. As long as the source current is flowing through the GFCI device it should operate as intended, breaking the circuit.

The only parts of this thread I'm sure I agree with:
GFCI, as the name implies, only protects against ground faults and only for circuitry plugged into or downstream of the GFCI device. It does not protect against all potential sources of electrical shock. It most definitely does not eliminate the need to de-energize electrical equipment being serviced.
GFCI works on the principle that source current (hot) and return current (neutral) should be of equal magnitude and opposite polarity during normal operation. Any difference in those currents is presumed to be current going to ground via an unintended, therefore potentially dangerous, path causing the device to open the circuit. It does not matter if there is actually current going to ground or how it is getting there, that is not part of the operating principle.
Presence of water increases the severity of shock by a combination of improving grounding and decreasing skin resistance of the human, meaning more amperage through the body.

- David

[Hobbyman2]

I'm not sure what you mean by 'ground fault passing through the device

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Thanks David,

The definition of ground fault from where I am is a direct short short , A direct short is when electrons find an alternate path to a ground source that offers no resistance, such as water or a broken wire contacting the grounded metal cabinet of an appliance. touching the hot and neutral or ground in a live circuit , dropping a hair dryer in a sink of water , I can think of many other situations that would cause a fault directly to ground but this should give a decent description. as to how a GFCI breaker works internally that is another topic . based on what I know , in a general explanation they work on a thermomagnetic release . I have never tore one apart or had any reason to .

[Hobbyman2]

I am trying to understand the situation you describe with skin contact, you mentioned the resistance of human skin,, however no mention of the body being a conductor ? pure water is non conductive ,H2o has no conductive materials as far as I know , it is nonconductive , it is the minerals in the water that are conductive, resistance in water can be manipulated by minerals , your body and blood, along with being mostly H2o water has iron and other conductive materials that make it conductive ,no ohms test can give a exact conductivity reading of every one in the world at any given time ?? less resistance would mean electrons can travel with less energy or restrictions as long as there is conductivity , bigger wire = a balance of resistance ??

[DLB]

I'm not sure what you mean by 'ground fault passing through the device

==================
Thanks David,

The definition of ground fault from where I am is a direct short short , A direct short is when electrons find an alternate path to a ground source that offers no resistance, such as water or a broken wire contacting the grounded metal cabinet of an appliance. touching the hot and neutral or ground in a live circuit , dropping a hair dryer in a sink of water , I can think of many other situations that would cause a fault directly to ground but this should give a decent description. as to how a GFCI breaker works internally that is another topic . based on what I know , in a general explanation they work on a thermomagnetic release . I have never tore one apart or had any reason to .

Your definition is inconsistent with the NEC and UL use of the terminology. I'm not going to re-define all of the terms you used because their definitions vary. We use a four wire system for household power. The intended path of 115 VAC in U.S. household power is from either hot to neutral, and never to ground or the other hot. The intended path of 230 VAC in U.S. household power is from Hot 'A' to Hot 'B' (names vary) and never to neutral or ground. With few exceptions ground is not used as a return path.

And I agree, in advance, that the definition of Ground Fault varies as well. But it is English. 'Ground' is defined and 'fault' is defined. Current going from hot to neutral, per your definition, is not a ground fault. Ground and Neutral are connected outside the structure and should not be connected anywhere downstream of the load center (circuit breaker panel).

I presume the subject of this thread is specifically Class A GFCI. Circuit interruption is mandatory from 6 milliAmps (mA) and up in specific branch circuits. Non-interruption is mandatory from 0 to 4 mA. Interruption may or may not occur between 4 mA and 6 mA. How long the device has to interrupt the circuit depends on the amount of 'ground current,' time decreases as ground current increases. How the device works is only relevant because it modifies or redefines the terms. Approved GFCI devices monitor hot and neutral current looking for a difference, i.e. current that is not following the intended path. If that difference exceeds ~ 5 mA for a defined period. Which means that the fault current need NOT pass through the device.

Summary: a ground fault, as those terms should be used in a discussion of Class A GFCI, is any current not following its intended return path from ~ 5mA on up. Does not matter whether the resistance on the intended path is low (a hot wire in direct contact with a grounded chassis) or high (a high impedance human). The trip point is ~5mA for human safety. Other classes have other trip points not meant for human safety. The design assumes the worst case, that the current not following its intended path is flowing through a human to ground since it has no way of knowing what the current is going through or what return it is following.

- David

[Hobbyman2]

Thanks David

I went out of the box this morning and asked Google and this discussion came up .

Is it possible to be electrocuted from a properly functioning GFCI circuit?.

Yes you can be electrocuted even with an operating GFCI. A GFCI will only trip if current goes from the hot and does not return on the neutral. That means it will trip if you stick a fork into the hot and jump into the bathtub / touch the fridge while holding it (because the current on the hot is NOT seen on the neutral - the power is escaping through the water or fridge chassis to ground).

A GFCI will not trip if you grab one fork in each hand and respectively stick one fork into the hot and another into the neutral (because all the current on the hot is also seen on the neutral). At that point, you're relying on the current operated circuit breaker, which will only trip once the current exceeds its rating (which it may or may not do while going through your relatively high-resistance body).

A GFCI works by making sure that amperage is equal at all times between the hot and neutral sides of the circuit. If this is ever not true, power is "leaking" from the circuit because of a short to ground, either "safely" through an appliance's metal shell to the ground leg of the outlet, or unsafely through you to something else that's earthed like metal plumbing.

https://diy.stackexchange.com/questions ... ci-circuit

I can not speak for any credibility or certification of any one posting or the website .
That said I can speak for my own personal experience and training .
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That said my home has 3 wires entering the house from the pole, 2 insulated and a wire wrapped ground, the ground bar is connected to a ground rod out side the home, the other provide 220volt . It is my understanding codes for the earth ground rod requirements around the country are all different, in fact I was at a new home construction site a mile from here and the code was 2 grounding rods at 10ft apart bonded to one another . looks like they are now requiring a certain ohm from earth bonding to the panel ground bar . in fact doing research they have a special meter just for this .

[DLB]

... A GFCI will not trip if you grab one fork in each hand and respectively stick one fork into the hot and another into the neutral (because all the current on the hot is also seen on the neutral). At that point, you're relying on the current operated circuit breaker, which will only trip once the current exceeds its rating (which it may or may not do while going through your relatively high-resistance body).
...

It is the Tamper Resistant (TR) Receptacle, not the GFCI, that is intended to reduce the likelihood of this particular "hazard." They are primarily intended to prevent young children from poking things into receptacles that don't belong in them, but should work equally well for those that came up with this 'two fork scenario.' They have been part of NEC since 2008, I did not read the specific details of where in the home they are required.

- David

[JPG]

Geez am I ever glad I was not aware of this thread the past couple of days.

I am just gonna say there is bovine merde present but am resisting an urge to point it out.

Bottom line is:ground fault devices provide a safer environment(safer not absolute safe) and do need to be in damp/wet areas and outdoors.

[Hobbyman2]

Geez am I ever glad I was not aware of this thread the past couple of days.

I am just gonna say there is bovine merde present but am resisting an urge to point it out.

Bottom line is:ground fault devices provide a safer environment(safer not absolute safe) and do need to be in damp/wet areas and outdoors.

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LOL
Please ,,, chime in this is a educational thread , I am all ways looking to learn something new ? as afar as the TR plugs we have the TR GFCI receptacles in our kitchen and we hate them . at the time we needed them and they were the only things available in town .

[Hobbyman2]

... A GFCI will not trip if you grab one fork in each hand and respectively stick one fork into the hot and another into the neutral (because all the current on the hot is also seen on the neutral). At that point, you're relying on the current operated circuit breaker, which will only trip once the current exceeds its rating (which it may or may not do while going through your relatively high-resistance body).
...

It is the Tamper Resistant (TR) Receptacle, not the GFCI, that is intended to reduce the likelihood of this particular "hazard." They are primarily intended to prevent young children from poking things into receptacles that don't belong in them, but should work equally well for those that came up with this 'two fork scenario.' They have been part of NEC since 2008, I did not read the specific details of where in the home they are required.

- David

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You are correct about the TR plugs and safety , , I rewired a daycare facility years ago I recall the TR plugs being code , however I am not sure this was the intent of the comment . ? I understood the situation being described as the resistance through the body through the two forks in regards to the breaker tripping ?
I do believe we agree on one thing and that is safety .

[dusty]

Now I know why some forums close a thread "for further comment".