REDUNDANT GFCI

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domnic

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Electrical Contractor
gfci

gfci

kwired said:
How long of a run between the two GFCI's?

The longer the run the more capacitive leakage you may have causing undesired tripping.

If you want "double protection" that is fine but don't put one of them at the beginning of a long run.
Click to expand...

What you call a long run . at what length would capacitive leakage become a problem on #10 uf/wg on a gfci?
 
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big john

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Portland, ME
kwired said:
Sort of. Only thing they really care about is that current that goes out comes back on another monitored conductor, then there is also a signal injected that allows them to instantly trip on a neutral to ground fault even if no load current is otherwise present.
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Is this something that changed with the last revision on GFCI standards?

I ask because that definitely didn't used to be the case: That was a classic symptom of a NG fault if the GFCI didnt trip until something was plugged in.
 
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GoldDigger

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big john said:
Is this something that changed with the last revision on GFCI standards?

I ask because that definitely didn't used to be the case: That was a classic symptom of a NG fault if the GFCI didnt trip until something was plugged in.
Click to expand...
This is a feature of second generation receptacle GFCIs. Not sure what the history or current situation is on breaker type GFCIs.
I am pretty sure that the GF protection in AFCIs did not include that feature.
 
kwired

kwired

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Location
NE Nebraska
big john said:
Is this something that changed with the last revision on GFCI standards?

I ask because that definitely didn't used to be the case: That was a classic symptom of a NG fault if the GFCI didnt trip until something was plugged in.
Click to expand...
They have been that way for at least 25-30 years.
 
don_resqcapt19

don_resqcapt19

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iwire said:
I do not believe so, I am fairly certain that has been in the last 10 years.
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It is only been in the past 10-12 years that the GFCI could detect a neutral to ground fault without a load.

All of the listed GFCIs being manufactured now are of the "self-testing" type. They automatically test themselves and either lock out the power or give an audible and/or visual indication of the failure.
 
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user 100

Senior Member
Location
texas
tom baker said:
This drawing is no different than the instructions included with the GFCI.
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And I think I see where iwire was coming from about commercial kitchens not wanting this- instead wanting to be able physically see the gfci in the kitchen. The gfci being right there next to the equipment ensures compliance and makes it easier to reset instead of going to breaker tucked away in a panel.
 
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mgookin

mgookin

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Location
Fort Myers, FL
user 100 said:
And I think I see where iwire was coming from about commercial kitchens not wanting this- instead wanting to be able physically see the gfci in the kitchen. The gfci being right there next to the equipment ensures compliance and makes it easier to reset instead of going to breaker tucked away in a panel.
Click to expand...

Very bad things happen when restaurant workers are in a panel.
They turn of freezers and coolers and don't turn them back on.
There are often many panels and they don't know which one to go to.
They don't know the difference between on, off and tripped so they just start switching everything.
Having the GFCI at point of use eliminates all of those problems and saves time too.
 
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curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
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Electrical Contractor
don_resqcapt19 said:
It is only been in the past 10-12 years that the GFCI could detect a neutral to ground fault without a load.

All of the listed GFCIs being manufactured now are of the "self-testing" type. They automatically test themselves and either lock out the power or give an audible and/or visual indication of the failure.
Click to expand...

Neutral to ground faults have tripped GFCI's as long as I can remember. I believe the electronics in older versions (not sure about the new "smart" versions)are connected to the load side so it provides enough load to trigger the ~6ms trip threshold.
 
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curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
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Electrical Contractor
iwire said:
Curt, that was always true when there was a load on the circuit.

Now they trip load or no load
Click to expand...

Bob, old GFCI's would trip without any additional load on the circuit. For as long as I remember I have been able to trip a GFCI by touching the load neutral to ground.
 
don_resqcapt19

don_resqcapt19

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curt swartz said:
Bob, old GFCI's would trip without any additional load on the circuit. For as long as I remember I have been able to trip a GFCI by touching the load neutral to ground.
Click to expand...
I never saw that until they changed UL 943 to require neutral ground fault protection.
 
iwire

iwire

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Massachusetts
curt swartz said:
Bob, old GFCI's would trip without any additional load on the circuit. For as long as I remember I have been able to trip a GFCI by touching the load neutral to ground.
Click to expand...

I have been in the trade since the early 80s and it has only been fairly recently I have found them to instantly trip.
 
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