shelly

Hi.
one of my customers complains the in the middle of the night their GFI shuts off the power in the house. They are able to restore power by turning off a specific c/b that has connected to it 2 rooms on the first floor and outside lighting. After about 2-3 hours they turn on that c/b and the electricity is is good for 2 or 3 days and than again same story. It could also happen 2 or 3 nights in a roll and than again all is good for a while. According to them there is nothing on in those room or out side than. Twice I have been on site can't find anything wrong. I check with a digital Megger and the ground - neutral is 0.92 meg from the top of each c/b to ground was about 0.41. In the mean time I disconnected the halogen spot light that are outside.
The house has 3 phase electricity. I am out of Ideas HELP
Thanks

sparky.jp

You're probably on the right track as far as looking more carefully at that outdoor light(ing).

One possibility--dew forms on or inside the outdoor fixture/socket during the night, causing enough leakage current for the GFCI to trip.

Another (long-shot) possibility is that a motion sensor (if there, on the outdoor lights) could be causing intermittent GFCI tripping.

Try disconnecting the outdoor part of the circuit for a week or so, to see if the problem disappears.

brian john

Isolate the circuit, and megger it. Giving just the neutral readings means little unless you tell us whether it was isolate/disconnected from the neutral termination block.

What level do your GFCI's trip at?

Have you checked the GFCI circuit breaker or swapped it with another CB?

Megger.

__________________
Brian John
Leesburg, VA

waco

I agree with looking at the outdoor lighting first. I'm also wondering why the general circuits are on a GFCI.

shelly

Hi,
Working voltage here is 220v. The GFI is connected after the main circuit breaker so that the entire house is protected. My main problem is I never sure what is considered good insulation testing measurements.
Thanks

frenchelectrican

Shelly.,

As soon I did see that you are from Israel any chance you may get the GFCI mixed up with RCD { resduie current leakage detector } ?

Both are simuair but funcitionwise, No they are not the same due diffrent trip rating and senstivty level.

If your system basised on UK format it should be pretty easy to pinpoint { I am far more famuair with French or USA system but dealt with UK from time to time }

What you should do is megger the supected circuit and isolited that conductor and run the Megger tester to verify to make sure the both netual and active { live } conductor is good to use.

Did you have recent wet weather that time ? if so it may cause the issue.

If you are not really famiaur with the system and set up you should get a hold of electrician in your area to assist you on this matter.

Merci, Marc

__________________
Bleu est beau.

shelly

Hi All
1, I am sure that it is a GFI and not RCD
2, We are in the middle of a draught here but it is a bit dewey at night.
3, Our GFI trip around 0.30 Meg
4, I didn't swap out the GFI it is relatively new. The house is wired for 3 phase wiring and it only happens in 1 specific C/B. Hard for me to belive that 1 phase is bad
5, There are no photo cells or motion detectors on that circuit.
6, This time I was there I only checked Megger on the main board, when the board measured 0.9 Meg I didn't check the individual circuits.

I was there about 5 week ago for the same problem but that time the megger measurement were bad and I started to disconnect everything from the main neutral till I fount the problematic branch. I disconnected both the natural and ground from the main board this time the main board tested fine.
Slowly I disconnected everything from the bad circuit looking for the bad branch. None of the branches tested bad. Reconnected everything tested between neutral and ground wires at the main board but not connected the circuit tested fine reconnected then to the main board and tested the main board again and all was fine for the last 5 weeks.

That should cover all of the suggestions and questions

Thanks
Shelly