Tripping GFCI outlet

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Riograndeelectric

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Lakewood Colorado
OK I had a service call this morning on an office Loft. The building is a 2 story old warehouse converted to Office condominiums in the 1980s. All wiring is either EMT exposed or type AC cable in concealed walls. Most of the home runs are type AC cable directly to the panel.

There is a small galley style kitchen
There is a GFCI installed on the wall of the kitchen that then feeds a counter top outlet then feeds a Peninsula outlet. The wire that feeds the GFCI is Type 12-2 AC cable no shared Neutral

every Morning when the Employees come in and turn on the overhead lights the kitchen GFCI outlet trips.
After resting the GFCI, it is fine, you can turn the lights off and on again, and the GFCI will not rip.
The lights that trip the GFCI are line voltage track with no dimmer switches.

All lighting in the office is feed from 3-wire type AC cable.

I took the GfCI outlet out, rang out all the circuit, and verified it is not part of multi wire branch circuit or that the GFCI was not feeding any thing other than the Kitchen.

Any one has any idea why the GFI trips only in the morning when the light are turned on by the wall switch?
The owner told me this has been going on for several years and that another Electrician had replaced the GFCI outlet last year
 
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The lights being turned on may not have anything to do with theGFI tripping.I had a GFI tripping in the morning when someone went into the break room and turned on the lights long story short coffee pot had a bad cord and the vibration from opening the door shorted it and tripped the GFI
 
the switch is right nex to the door and the GFI will only trip in the morning first thing when you turn on the lights but after opeing the door.
If the door could be a suspect then the GFI should trip all day long as people go in and out of the door.
there is a micorwave/ contertop style pluged inot the circuit . but GFI ony trips once a day.
 
I tend to be suspicious of my information sources, when I hear stories that defy reasonable explanation. Here?s a bunch of questions to ask yourself or to ask some of the employees:
? Have you been present, first thing in the morning, and observed this yourself?
? Is it always the same person who is first through the door, and is reporting this symptom without there being any other person nearby to confirm the occurrence?
? Have they ever tried a semi-scientific experiment, such as having one person walk softly through the door and stand by the GFCI device, and giving a count-down: three, two, one, turn on lights, so that the exact moment of the trip can be truly correlated to the throwing of the switch?
? Does the trip happen at the exact moment the switch is thrown?
? Do the lights come on instantly, or is there a slight delay (such as a fluorescent lamp would have)?
? If there is a delay between throwing the light switch and the lights being on a full brilliance, at what exact point during the light startup cycle does the GFCI trip take place?
? Is there anything plugged into that GFCI receptacle?
? Would it make a difference if something is plugged in one day, and not plugged in the next day?

And the really big question:
? Are you focusing your attention on the wrong outlet? Is there a load fed downstream of the GFCI device, and is it possible that some aspect of the downstream load is causing the problem?
 
Cahrlei.

answers to your questions.

1. I have witnessed this in person. I meet the employee at the door first thing and before the lights were turned on I stood with in sight of the GFI and switch and saw the GFI trip.
2. lights come on to full brightness right away.

3. as far as I can tell by tracing out the circuit today there is nothing else on the circuit but 3 kitchen outlets with a counter top style microwave pluged ino the circuit.
is there any chance that there might be an imbalance on a nuetral condcutor from another circuit adjacent to this,

the circuit was terminated on a twin Breaker but not sharing a neutral though.

these are very good questions that you aked. I agree with in being a non beliver with out witnessing the event.

thnak you for the great advice.
 
The most disturbing aspect of this problem is its non-repeatability, except one time per day. What is needed here is a list of all possible things that might be different later in the day than they are first thing in the morning.

For example, lights that have been on for a while are warmer than lights that have been off all night. So if you turn the lights off and then on in the middle of the day, the process of the lights turning on might be slightly different simply because the lights are already hot. Not likely, I admit. But it serves as an example. To prove or disprove the influence of the lights being hot, you could turn the lights on in the morning, watch the GFCI trip, then immediately turn the lights off again (before they can heat up), reset the GFCI, and turn the lights on again.

 
Do the lights flicker or go out when this happens? Lighting on load side - bastard neutral?

Do they also turn on the coffee pot while turning on the lights?

Is the morning and evening the only time this guy stands right on the screw in the cable below the floor?

Tin can stud work and metal boxes? If so all of the grounding is tied together this way as well - if say there were a neutral contacting on the load side of the GFI - and likewise the lighting+/or loose neutral - sounds unlikely but what the hay.... Stranger crap has happened before...

Either way I would go one further on tracing it by ringing it all out HNG to eachother all the way through the whole thing on the load and line side - the lighting too just to make sure. And make a line diagram of the whole thing - being able to visually have a full picture of it helps me a lot by removing speculation of what feeds what.

While you're putting the whole mess back together eliminate the load on the GFI by putting one at each point down the line - that way only one (hopefully) would go out when it happens again - if it does.... Whatever is plugged into that one is your problem. Some will scawf at the expense of say a half dozen GFI's but if it doesn't solve the problem out-right, it will help you find it the second time around with less interuption....
 
I have done this. truned lights on watched the gfci trip turn the lights off rest gfi turn lights back on with lights hetaing up for other than a minute or so. seems to have somehitng common with the Morning or the fact the lighting circuit rests or is off for a period of time.
I did move the gfi circuit to another breaker and opposite phase to see if that makes a differance.
 
Riograndeelectric said:
I did move the gfi circuit to another breaker and opposite phase to see if that makes a differance.
Click to expand...

Wouldn't do that unless you are absolutely sure it is a two wire circuit all the way with no bastards. GFI's trip due to an impalance (measured current) on line and neutral. Which is also another way to check.... measure line and neutral current to see if they match.
 
try this go in the morning put a tester in the CFI and manually trip it before turning on the lights reset the GFI then turn on lights.We had an alarm system that was repeatedly going off at night in a large cubical office area,we could find nothing wrong with the system.I was just about to throw in the towel when I noticed above one cubical a helium filled mylar balloon gently swaying back and forth as the air from the ductwork blew it.THe manager sent a memo that all ballons had to go home at nite and we have not had a alarm sinse.
 
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