Problem with G.F.I .C.B feeding G.F.I Spider boxes

[Randall Flagg]

Hello Everyone,

I am having an issue that I could sure use some guidance with. I have a job site where I am providing temp power for site construction. I have several dry type 75 KVA transformers onsite. Coming off of the secondary distribution I have 50a GFI breakers tied in to 50a Hubble twist locks. The issue is when ever a Spider box with GFI receptacles is tied into the 50a GFI receptacle the breakers instantaneously trip, with no load. I replaced the 50a GFI breaker with a standard two pole and the GFI spider boxes work fine, they do not trip with load and without. The inspector has now said I need to feed the GFI spider box with a 50a GFI breaker. Problem is, as aforementioned, they instantaneously trip. Power is fine phase to phase, phase to neutral, phase to ground. my questions are:

1) is there a reason this would be happening? Is there something I should check? redundancyin G.F.I's?
2) Is there a code reference that I could use that would allow me to not have to feed a GFI spider box( in which all the receptacles are GFI protected) with a GFI circuit Breaker?

Thank you in advance any assistance received.

 

[GoldDigger]

The most likely cause is that there is an inadvertent neutral to ground connection in the spider box.
Even the GFCI receptacles that self test when turned on do the test by bypassing some current around the detector internally instead of actually sending current to ground.

 

[kwired]

You have a ground fault between the 50 amp plug and the spider box, or excessively long cords and are getting enough leakage to cause nuisance trips.

If the problem is excess cord length or can you eliminate the 50 amp receptacle and hard wire? GFCI is only required here because of the presence of the 50 amp receptacle. However if you have a neutral to ground fault you should repair that problem either way.

 

[electricalist]

Hello Everyone,

I am having an issue that I could sure use some guidance with. I have a job site where I am providing temp power for site construction. I have several dry type 75 KVA transformers onsite. Coming off of the secondary distribution I have 50a GFI breakers tied in to 50a Hubble twist locks. The issue is when ever a Spider box with GFI receptacles is tied into the 50a GFI receptacle the breakers instantaneously trip, with no load. I replaced the 50a GFI breaker with a standard two pole and the GFI spider boxes work fine, they do not trip with load and without. The inspector has now said I need to feed the GFI spider box with a 50a GFI breaker. Problem is, as aforementioned, they instantaneously trip. Power is fine phase to phase, phase to neutral, phase to ground. my questions are:

1) is there a reason this would be happening? Is there something I should check? redundancyin G.F.I's?
2) Is there a code reference that I could use that would allow me to not have to feed a GFI spider box( in which all the receptacles are GFI protected) with a GFI circuit Breaker?

Thank you in advance any assistance received.

is there any chance this trips the way a gfci does if the load side is feeding another gfci line side?

 

[kwired]

is there any chance this trips the way a gfci does if the load side is feeding another gfci line side?

GFCI feeding another GFCI should not trip in general. There is no place for current to leave the intended circuit conductors and cause a trip. Fault current between the two would trip the upstream device. Fault current past the downstream device - will trip one for certain - but most often will trip both.

 

[electricalist]

You are probably correct kwired. Too long ago when we would hot check a house and someone hadnt line sided the hot in and out to the next gfi then it would trip,,but again it was long ago ..

 

[kwired]

You are probably correct kwired. Too long ago when we would hot check a house and someone hadnt line sided the hot in and out to the next gfi then it would trip,,but again it was long ago ..

If you are temporarily supplying a new building from a temp outlet that is GFCI protected - you can easily have troubles if the EGC's are all connected to the neutral bus, you may get lucky if there is no EGC connected to anything in contact with any ground potential object, but those troubles are almost definitely happening if there are any grounding electrodes connected to the GFCI load side neutral. If supplying the service panel in this way you need to temporarily remove bonding jumper and isolate neutrals and equipment ground conductors from each other. This is a good test for finding ground faults in your wiring though.

 

[mwm1752]

Hello Everyone,

I am having an issue that I could sure use some guidance with. I have a job site where I am providing temp power for site construction. I have several dry type 75 KVA transformers onsite. Coming off of the secondary distribution I have 50a GFI breakers tied in to 50a Hubble twist locks. The issue is when ever a Spider box with GFI receptacles is tied into the 50a GFI receptacle the breakers instantaneously trip, with no load. I replaced the 50a GFI breaker with a standard two pole and the GFI spider boxes work fine, they do not trip with load and without. The inspector has now said I need to feed the GFI spider box with a 50a GFI breaker. Problem is, as aforementioned, they instantaneously trip. Power is fine phase to phase, phase to neutral, phase to ground. my questions are:

1) is there a reason this would be happening? Is there something I should check? redundancyin G.F.I's?
2) Is there a code reference that I could use that would allow me to not have to feed a GFI spider box( in which all the receptacles are GFI protected) with a GFI circuit Breaker? Are you in compliance with 590.4(B)? 590.6(B)(1) GFCI protection for personnel -- your 125v 15A thru 30A branch circuit breakers feeding specific recepts within the spider assembly provide that -- IMO no need to protect the 240v 50A feeder -- I prefer the recept feeding the spider box to be specific for the purpose. I would ask the AHJ where is the code that the protection is required.

 

[kwired]

Hello Everyone,

I am having an issue that I could sure use some guidance with. I have a job site where I am providing temp power for site construction. I have several dry type 75 KVA transformers onsite. Coming off of the secondary distribution I have 50a GFI breakers tied in to 50a Hubble twist locks. The issue is when ever a Spider box with GFI receptacles is tied into the 50a GFI receptacle the breakers instantaneously trip, with no load. I replaced the 50a GFI breaker with a standard two pole and the GFI spider boxes work fine, they do not trip with load and without. The inspector has now said I need to feed the GFI spider box with a 50a GFI breaker. Problem is, as aforementioned, they instantaneously trip. Power is fine phase to phase, phase to neutral, phase to ground. my questions are:

1) is there a reason this would be happening? Is there something I should check? redundancyin G.F.I's?
2) Is there a code reference that I could use that would allow me to not have to feed a GFI spider box( in which all the receptacles are GFI protected) with a GFI circuit Breaker? Are you in compliance with 590.4(B)? 590.6(B)(1) GFCI protection for personnel -- your 125v 15A thru 30A branch circuit breakers feeding specific recepts within the spider assembly provide that -- IMO no need to protect the 240v 50A feeder -- I prefer the recept feeding the spider box to be specific for the purpose. I would ask the AHJ where is the code that the protection is required.

I was thinking 690.6(B)(1) would require GFCI protection on the 50 amp outlet - but after reading carefully maybe it doesn't - but only as long as this receptacle is intended to supply those spider boxes and not some other piece of equipment. Bring in some 240 volt tool and plug it into that same 50 amp receptacle and GFCI is required from what I can tell.