Hot to Neutral Resistance

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Sully71

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Have a weird problem. New construction. One 20 amp circuit consisting of about 8 outlets. GFCI outlet at beginning of the run. Tripped and will not reset. Disconnected line and load. Placed ohmmeter on load side. Load side is acting like a capacitor. Meter rings up from 6 Megohms to open circuit. Reverse leads and get the same readings. Circuit works fine with regular outlet in place of GFCI. Any ideas? My guess is that the GFCI is sensing the resistance even though it is very high. I'm going to try splitting up the circuit tomorrow to narrow it down. Any help would be greatly appreciated.

Kevin
 
sparky_magoo

sparky_magoo

Senior Member
Location
Reno
Re: Hot to Neutral Resistance

With the regular outlet installed, Have you tried placing a sensitive ammeter in series with the hot lead?
 
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Sully71

Member
Re: Hot to Neutral Resistance

Good idea. I'll try that in the morning and reply with my findings. I have a Fluke 87 which does read mA. It wouldn't be as difficult a problem if it was a constant high resistance reading. It just acts like I'm charging and discharging a cap. when I ohm it out. Weird. Thanks for the help.
 
sparky_magoo

sparky_magoo

Senior Member
Location
Reno
Re: Hot to Neutral Resistance

A fluke 87 is perfect. I use one too. A clamp meter might not be sensitive enough to detect a few mills.

If your fluke shows current flowing, you could keep moving the meter further down stream until the current goes away. This might isolate what section of the branch is faulted.
 
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Sully71

Member
Re: Hot to Neutral Resistance

Thanks Sparky. I really didn't think to go the current route instead of resistance. I'll let you know how it goes.
 
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Sully71

Member
Re: Hot to Neutral Resistance

It was bugging me so I just did a quick check at the beginning of the run. Got roughly 4.0 micro amps max. I'll have to check the specs. on this GFCI. I'll work my way down the circuit in the AM. Of course I pigtailed everything so it should be fun.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Hot to Neutral Resistance

Using a Fluke 87 for this type of basic line voltage troubleshooting is somewhat like using watchmaker tools to pound a spike.

I have an 87 and it's a great meter, however often when checking continuity between two open conductors in the same cable will produce the readings you describe.

For this type of troubleshooting I suggest using a basic wiggy with continuity testing ability.

Now have you checked on the GFCIs load side field wiring for continuity between the grounded and grounding conductors?

There should be none.

My guess on this problem is one of two things

1)You have continuity between the grounded and grounding conductors on the load side of the GFCI.

2)You have a bad GFCI, it happens.

Will it reset without the load side wiring connected?

If you had 'true' continuity between 'hot and neutral' the breaker would trip not the GFCI.

[ September 25, 2005, 10:52 AM: Message edited by: iwire ]
 
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jeff43222

Senior Member
Location
Minneapolis, Minnesota
Re: Hot to Neutral Resistance

I agree with Bob. With one exception, every time I've run into this situation, the problem was that the bare grounding conductor was touching some part of the neutral. I always tape up the exposed screws to try to avoid this, but sometimes the bare grounding wire finds its way past the tape when I push the device into the box.

The one exception was a bad GFCI.
 
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Sully71

Member
Re: Hot to Neutral Resistance

Thanks for all of the help guys. It turns out that I'm an idiot! I forgot I pigtailed in a low voltage electronic transformer. Ran the hot to the switch first and then on to the input side of transformer. Neutral and ground were connected through with the rest of the outlets. Disconnected the transformer completely and rung out the hot and neutral inputs. Got the same cap. like reaction (I'm guessing I really am charging a cap.). Put the GFCI back in the circuit and had no problems. Now I just need to figure out how to feed this low voltage circuit in closed up walls. Fun stuff! I really need to stop doing work on my own home after 14 hour days! Thanks again.
 
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