GFCI's do not need an EGC (moved from another thread)

[roger]

Could we agree that when an equipment that is equipped with a grounding conductor will activate the GFI faster if there is a ground fault to the metallic case

We can agree but, in this case we wouldn't need a GFCI at all, the EGC being a low impedance path back to the source would cause the OCPD to open. This is the theory behind the exception to using GFCI's in 590.6(B)(2), with an assured grounding program GFCI's are not necessary.

Note; I'm not saying that GFCI's are not a good idea even with the assured grounding program in place.

Roger

 

[cowboyjwc]

It's not gravity that holds me to the earth. It's all those hungry, free electrons in my body somehow searching for that mystical buffet below my feet called the ground.

Either that, or heaven is repelling me.

I vote for the second one. :grin:

The angels don't want me and the devil's afraid I'll take over.:grin:

 

[ultramegabob]

gravity doesnt need a ground to work....

 

[iwire]

gravity doesnt need a ground to work....

No, but the ground is often painful result of gravity. :grin:

 

[LarryFine]

Bottom line: a GFCI will function for its specified purpose (limiting shock current to a specified generally acceptable value) without and EGC. But it will be far more effective at its accepted purpose (preventing shock) with an EGC present.

In my opinion, the presence and effectiveness of a proper EGC has no interaction with the presence or effectiveness of a GFCI device.

If an EGC connection minimizes the voltage-to-earth of a metallic enclosure or housing, the presence of a GFCI has no bearing, and vice versa.

 

[cowboyjwc]

No, but the ground is often painful result of gravity. :grin:

My skydiving instructor said that it was the one law you couldn't break.:grin:

Parachute works or parachute doesn't work, the results are the same. The amount of damage is the only difference.:grin:

 

[LarryFine]

Suppose I connect one terminal of a battery to the input hot wire and the other terminal to the hot output slot of the GFCI. This will trip the GFCI.

Have you tried this, or are you just guessing? Where does the circuitry get its power?

 

[LarryFine]

Oh, and about this 'gravity' thing: it's just a myth.

The truth is simply that the earth sucks big-time.

 

[weressl]

We can agree but, in this case we wouldn't need a GFCI at all, the EGC being a low impedance path back to the source would cause the OCPD to open. This is the theory behind the exception to using GFCI's in 590.6(B)(2), with an assured grounding program GFCI's are not necessary.

Note; I'm not saying that GFCI's are not a good idea even with the assured grounding program in place.

Roger

Not quite true. GFI/GFCI was developed especially for speed as regular circuit breakers would not be fast enough to interrupt the electricity before irreversible damage or death to occur should the ground fault occur while the victim is holding the tool.

 

[weressl]

Oh, and about this 'gravity' thing: it's just a myth.

The truth is simply that the earth sucks big-time.

Hey you're welcome to leave any time........... or is gravity holding you back?

 

[weressl]

Have you tried this, or are you just guessing? Where does the circuitry get its power?

If the current would be AC I would have an easier time to believe that it works, but I would not think that the current sensor around the two conductors is a hall effect sensor. Why would they spend the extra money?

If it work, it works for a different reason that he thinks. In other words, he is missing the point.

 

[roger]

Not quite true. GFI/GFCI was developed especially for speed as regular circuit breakers would not be fast enough to interrupt the electricity before irreversible damage or death to occur should the ground fault occur while the victim is holding the tool.

I am not disputing the reason for GFCI technology or the common sense of using them, but the truth is, under a 590 application and an assured grounding program in place, GFCI's are not necessary because in the event of a ground fault most of the current will be shunted around the user.

Roger

 

[don_resqcapt19]

Not quite true. GFI/GFCI was developed especially for speed as regular circuit breakers would not be fast enough to interrupt the electricity before irreversible damage or death to occur should the ground fault occur while the victim is holding the tool.

With a correctly installed and functioning EGC, there should not be a hazardous voltage and if there is, there will be enough current flowing to get into the instantaneous trip range of the breaker so the hazard will not exist for long. The only hazardous voltage on the conductive parts that are connected to the EGC is the voltage drop that results from the flow of the fault current. If there is less fault current, then there is less voltage drop on the equipment grounding conductor and less shock hazard.

 

[cschmid]

Oh, and about this 'gravity' thing: it's just a myth.

The truth is simply that the earth sucks big-time.

LMAO..

gravity is just a myth..kind of like you needing a ground on a GFCI..unless you are a piece of computer equipment then the ground is important but it does not care if it is GFCI or not..dang little electrons need to be stbilized..wild little buggers they are..

 

[gar]

080721-2135 EST

Larry:

For convenience I should not have use the battery as a direct source of a current, but the battery could be used to generate an AC current. No there is not a Hall device in the GFCI. However, a large enough unidirectional current pulse would probably trip the GFCI.

My assumption was that the GFCI was connected to a AC source and therefore it had power to operate. All I wanted to point out was that an added current to the hot wire that was not directly referenced to neutral or ground would still trip the GFCI.

.

 

[crossman]

If the GFCI was connected properly to an AC source, and you had an AC load properly plugged in to the receptacle, and you placed the battery leads with one on the "hot" feed conductor to the receptacle, and one on the "hot" protected conductor to the load, I think the GFCI just might trip.

 

[cschmid]

all you need is an old fan motor that is bad and plug it in..done deal..:grin:

 

[weressl]

I am not disputing the reason for GFCI technology or the common sense of using them, but the truth is, under a 590 application and an assured grounding program in place, GFCI's are not necessary because in the event of a ground fault most of the current will be shunted around the user.

Roger

Most, but may be insufficiently large in proportion to assure that no personal injury occurs. Remember that a ground fault could be thousands of amperes yet 1/10th of an Ampere is sufficient to kill a person.

The assured grounding program does not assure that the complete return impedance is low enough so the parallel current through the person will be low enough to be harmless. The assured grounding program only tests the EGC from the receptacle to the apparatus not from the receptacle to the bonding point.

 

[ELA]

What fun, this has gone theoretical.

Gar, Crossman,
Sounds like it is time for some experiments :grin:

Would this trip a GFCI?

 

[76nemo]

What fun, this has gone theoretical.

Gar, Crossman,
Sounds like it is time for some experiments :grin:

Would this trip a GFCI?

I would say yes. You are injecting 30ma of current load side through a resistor/load after the current sensing coil, so there would an imbalance going back through on the ungrounded leg.