GFI Testing w/ Multimeter

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Thundermasmacho

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Portland, Oregon
I've wired six 20 amp/110volt outlets to a blank face GFI, and when I turn on power and try and click the reset button, the GFI keeps clicking off. I've double and triple checked that I have the line and load connections correct, I've swapped it with another new GFI, same problem persists. I bypassed the GFI just to see if the breaker would pop, and it didnt. Rather than pulling each outlet out of its box and checking the connections, is there a quick way to test each outlet with the multimeter to see where the problem is? If so, what should I be looking for?
 
Thundermasmacho said:
I've wired six 20 amp/110volt outlets to a blank face GFI, and when I turn on power and try and click the reset button, the GFI keeps clicking off. I've double and triple checked that I have the line and load connections correct, I've swapped it with another new GFI, same problem persists. I bypassed the GFI just to see if the breaker would pop, and it didnt. Rather than pulling each outlet out of its box and checking the connections, is there a quick way to test each outlet with the multimeter to see where the problem is? If so, what should I be looking for?
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The problem is most likely an unintended connection between the neutral wire and the EGC or other grounded surface somewhere on the load side of the GFCI.
Unfortunately a meter will just measure that continuity exists and not tell you where unless you get a very low ohm (less than 1 ohm) reading between neutral and EGC and can measure carefully enough to detect a fractional ohm difference in the reading from one place to another. The lower the reading, the closer you are to the problem.

NOTE: I am assuming that you are allowed to perform this sort of electrical work on your premises. Otherwise I would just recommend that you bring in a licensed electrician.
 
GoldDigger said:
The problem is most likely an unintended connection between the neutral wire and the EGC or other grounded surface somewhere on the load side of the GFCI.
Unfortunately a meter will just measure that continuity exists and not tell you where unless you get a very low ohm (less than 1 ohm) reading between neutral and EGC and can measure carefully enough to detect a fractional ohm difference in the reading from one place to another. The lower the reading, the closer you are to the problem.

NOTE: I am assuming that you are allowed to perform this sort of electrical work on your premises. Otherwise I would just recommend that you bring in a licensed electrician.
Click to expand...

I agree this is the most likely cause.

Presumably these receptacles are daisy chained to the load side of the GFI. I'd be inclined to start at the first receptacle and disconnect the wiring going to the rest of the receptacles one at a time and see where the problem is.
 
petersonra said:
I agree this is the most likely cause.

Presumably these receptacles are daisy chained to the load side of the GFI. I'd be inclined to start at the first receptacle and disconnect the wiring going to the rest of the receptacles one at a time and see where the problem is.
Click to expand...
The computer science jocks will tell you that the most efficient search for this type of problem is to start by disconnecting at the middle receptacle to see which half the problem is in, then keep dividing in half. It is called a binary search.
Since the OP installed the wiring, he knows where the middle is. In an existing building, you would have to guess at the routing, so the search would be less efficient.
 
ATSman said:
There is a plug-in module that has LEDs to indicate improper and proper wiring at the U ground receptacle. This may be quicker than removing each receptacle.

https://www.google.com/search?sourc...-ab..9.9.4462.0..0j0i131k1j0i20k1.7PjIZl0xijM
Click to expand...

OP can't even get power to the receptacle(s), so those aren't going to indicate anything. If he bypassed the GFCI and has neutral to ground fault or even neutral and ground reversed they will still indicate "correct" wiring.
 
kwired said:
OP can't even get power to the receptacle(s), so those aren't going to indicate anything. If he bypassed the GFCI and has neutral to ground fault or even neutral and ground reversed they will still indicate "correct" wiring.
Click to expand...
Ok, but after bypassing the GFCI and using this tester I still think by comparison checking he would have more info of the problem area than he has now, without disconnecting anything.
 
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