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Troubleshooting a GFCI Ckt in Kitchen

K

KTK

Member
Location
80221
Occupation
JW
The customer has one of their ckts in the kitchen that doesn't work. I found the Home Run (HR) box and installed a brand new GFCI Plug there. But, with the gfi plug installed, I was reading 123v from Hot to ground AND 117v from Neutral to ground. I was also reading 6 volts ACROSS the hot & Neutral on the plug.

I removed the plug and connected a piece of romex from the HR box to the next plug downstream - without the gfi installed - IOW, hard-wired from the HR box to THE PLUG downstream - and the rest of the plugs showed correct wiring, including that 2nd plug. I don't remember checking the voltage at the HR box WITHOUT the gfci plug installed.

Could it be a bad GFCI plug? Dunno what's going on... The voltage at the panel was all good.

Help... if you can! Thanks! Kirk
 
rambojoe

rambojoe

Senior Member
Location
phoenix az
Occupation
Wireman
You may have simply enough failed to reset (and or fully cycle after energized) the new gfi... I tried to visualize why you would externally jump the circuit downstream though, something that could be potentially dangerous (and scary to do in front of a h.o.)...
Anyway, such a low reading usually means its off, or your meter sucks...
Re-read it a 4th time, white to ground.... Ok.
Was there a red and a black in the box?
 
K

KTK

Member
Location
80221
Occupation
JW
I jumped the ckt downstream to determine if there was a short or open in the romex going from the HR box to the next box. Again, when I did that, WITHOUT the gfi in place, the plugs showed good / wired correctly. That was my hypothesis, that there is a problem in that connecting wire.

The gfi's red light came on, then went out and neither button worked - no clicking sound at all.

My plug-in tester said, "Hot & Grd reversed" and once "Hot on Neutral with Hot open" - neither of which I saw / found evidence for.

I believe my amprobe meter is good. I don't understand what you mean by = "such a low reading usually means its off,"

Thanks for your help!
 
rambojoe

rambojoe

Senior Member
Location
phoenix az
Occupation
Wireman
= ghost voltage... Barring the very rare defective device, look at it this way. Its worked all this time, and just a simple swap can do more harm than good. Anyway, you sure are describing a floating neutral... which, if its a mwbc h.r. you really gotta save "jumpers" until the last resort, and of course it can make pretty soot marks all over the place.
Either you didnt fully isolate the h.r. or it aint the h.r...
Did you fix it?
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Possibly line and load reversed on gfi. The gfi will be hot, but the load will not. That also explains the trip and reset buttons not working. Double check that line is actually line. Someone (homeowner) could have changed out the gfi and got it backwards, then called you when it didn’t work. I have seen this several times.
 
K

KTK

Member
Location
80221
Occupation
JW
rambojoe said:
= ghost voltage... Barring the very rare defective device, look at it this way. Its worked all this time, and just a simple swap can do more harm than good. Anyway, you sure are describing a floating neutral... which, if its a mwbc h.r. you really gotta save "jumpers" until the last resort, and of course it can make pretty soot marks all over the place.
Either you didnt fully isolate the h.r. or it aint the h.r...
Did you fix it?
Click to expand...
"mwbc h.r."?
 
K

KTK

Member
Location
80221
Occupation
JW
hillbilly1 said:
Possibly line and load reversed on gfi. The gfi will be hot, but the load will not. That also explains the trip and reset buttons not working. Double check that line is actually line. Someone (homeowner) could have changed out the gfi and got it backwards, then called you when it didn’t work. I have seen this several times.
Click to expand...
I'm assuming I hooked the gfci up correctly... but, I've slept since then, so...
 
rambojoe

rambojoe

Senior Member
Location
phoenix az
Occupation
Wireman
readydave8 said:
Don't assume that those lights on plug-in tester are accurately describing problem
Click to expand...
The trick i learned after a while and many failed testers is push them in the recept only enough to get the reading... the bite on them hubbels and the tension on those awful tr gfis is what ruins the internals and loosens the tester blades..
 
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