Recently installed new 20Amp circuit for a Bathroom; it leads to a box in the attic where it splits into 3 runs; 1 GFCI outlet, 1 light over vanity and 1 light with vent.
I walk into a Bath today and noticed there is no power going to the GFCI receptacle. I have both lights and fan working but the receptacle won't reset and Test function doesn't work.... I opened the box and the tester show no Voltage....which is weird.

I go up on the attic - open the box and everything looks good...I touch the tester to each wire and all are hot except the one going to the outlet....so I am really baffled....black to black, white to white...ground checks...everything seems ok.

I run the tester by every wire again and now it shows power flowing in every hot wire.....so I come down to the bathroom and in fact now the GFCI works....I check all the connections - everything seems tight and firm...no lose connections.

I have an outlet tester and it shows everything OK

What was that ??

 

It is best to use a multimeter when checking for individual wire/circuit voltage. Tick tracers are good to detect the presence of electrical current, and that's about it. Good tool, but a specific job. It won't help in a crowded box. Is it possible that you wired the GFCI into one of the switch loops for the lights? So when you turn the lights on, you have power to the GFCI??

 

Sure sounds like you had a bad connection within a wire nut...assuming you used wire nuts in the jbox....

I'd kill the power, and remove the wire nuts and make sure all the wires are stripped properly and lined up. If you have enough wire length, strip the wires a little longer and twist them tightly before reinstalling the wire nuts.

 

I am guessing CT has identified the most likely issue...I mean, everything worked for about a month now and since I like to do things neat I pulled each Romex cable through its own 1/2inch knock-out and the box is big enough to easily trace each wire from each cable.

Will have to go up and see what's up with the black wire nut....Glad I always wrap them with black electrical tape for extra protection.....if indeed I made the connection weak and it somehow got lose after a month - it could create a spark

 

Update:

Lesson learned - I undo the electrical tape and right away smell the typical odor of electrical arc.
3 of the black wires are secured but the fourth one is lose and all ends are actually blackish...
Thanks for the GFCI that it tripped - otherwise I wouldn't have known....

Cut the burned ends - took 20 min to triple align all the wires and make sure they are in perfect contact along the entire length where exposed.
Still it's a b...t to twist the wire nut over four wires that are AWG12....from now on - I will buy only the wire nuts with wings.
Scared to think what could have been.....

 

Thanks for letting us know you got it.There should have been no electrical tape. It serves no purpose if the connection is properly made except to make a mess as it ages. While to twist or not to twist is an old debate if you have that much trouble just twist together first using linesman pliers.

 

BTW.... I can't imagine how - but maybe there is some sort of tester / device that can tell you if there is lose connection.... I don't know...based on heat generated or maybe it can measure minute differences in electromagnetic field ??

Now I feel like I have to open every J-box and verify if all connections are solid

 

There is, but if you have to ask how much it costs, you can't afford it You could buy a non contact infrared thermometer and zero it in on each jbox to see if there is an abnormal amount of heat coming from it. Not expensive. PRO-SERIES Non Contact Infrared Thermometer with Laser Sighting, 12:1 Spot-THERMNC - The Home Depot

 

well....the funny thing about that saying "...if you have to ask how much...." is that curiosity get the better of me and now I really wonder; how much those instruments cost and how do they check for partial connections

 

Oddly enough I asked our POCO guys last week when they were locating a broken conductor in our underground primary, and they said in the thousands. It was on wheels, so it must have been heavy. They found it, pinpointed within a foot, dug part of my yard up and fixed it. Better than hit and miss, I guess.