ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
You will never guess
by Bill Addiss - 02/24/21 04:45 PM
Lock-down Thread
by Bill Addiss - 02/24/21 04:40 PM
New tool
by SMOKEYBOB - 02/15/21 04:59 PM
Split Bus Breaker Panel
by gfretwell - 02/15/21 02:30 PM
Sierraplex recpts
by gfretwell - 02/15/21 02:27 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 23 guests, and 18 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
1000 amp gfci breaker #204890 01/18/12 11:37 PM
Joined: Feb 2007
Posts: 12
TNT_Tim Offline OP
Hi guys, haven't been on in a long time. Have a weird problem I'm on tonight. 1000 GE breaker serving a gym. At night when they turn off lights to the pool area. 4 circuits controlled by contactor. Controlled by one single pole switch. The 1000 main in the mdp trips. Controls and lighting circuits are in a 225 amp sub fed from mdp. It doesn't trip when turning lights on only when turning lights off

Any thoughts, I'm a little stumped

Last edited by TNT_Tim; 01/18/12 11:41 PM.
Work Gear for Electricians and the Trades
Re: 1000 amp gfci breaker [Re: TNT_Tim] #204892 01/19/12 12:00 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Defying all logic .....

My dad's GFCI (early 80's) for the pool filter kept tripping for some unknown reason. It turned out that it tripped whenever someone rang the doorbell. I guess the little arc in the doorbell contacts leaked just enough current to trip it.

If that was really the case - removing the doorbell from the pump circuit solved the issue back then - perhaps your problem is something as simple as worn switch contacts, ane replacing the contactor points will solve the problem.

Re: 1000 amp gfci breaker [Re: TNT_Tim] #204893 01/19/12 02:36 PM
Joined: Jul 2004
Posts: 783
LarryC Offline
Pool lights = humidity = water condensation = wet insulation

Quick check to isolate the problem, does it still happen when the four circuits feeding the lights are turned off but you still operate the lighting contactor?

If so, I would suspect the inductive kick generated by the lighting contactor is punching thru insulation and find its way to ground. Is there any sort of RC snubber across the contactor coil to reduce the magnitude of the inductive kick? If not, try adding one to see if that cures the problem.

If it does not happen when the lights are off, try the individual lighting circuits one at a time to isolate the trouble making circuit.

Re: 1000 amp gfci breaker [Re: TNT_Tim] #204894 01/19/12 05:34 PM
Joined: Apr 2002
Posts: 7,233
HotLine1 Offline
I had a bad 277 volt, F40 T-12 ballast self destruct and trip a 2000 amp main w/GF. Never tripped the branch CB on it's way.

Try what Larry suggested.

Re: 1000 amp gfci breaker [Re: TNT_Tim] #204899 01/19/12 09:10 PM
Joined: Feb 2007
Posts: 12
TNT_Tim Offline OP
Thank you so much guys, nice to know there still is a good resource of knowledgable people.
Little follow up after last night , contactor is mechanically held, GE open face 25+ years old in a very humid environment with constant chlorine vapors present. Needless to say you can imagine its condition. I did try what Larry said last night, problem is def in control circuitry. Lights deenergized still tripped, going to replace contractors tonight and test a few more things that came to me while sleeping lol. I believe open relay coil is leaking on power to open contactor. Going to amp ground tonight and see what's on it. I need to make a correction as well it is NOT a GFCI main it is a GFP main. Let go thresholds are 100 times greater on these that's why I'm gonna amp grounds tonight. Again thanks guys stay safe and will update later and try to visit more.

And Reno , how's all the cats bud, prob a few new additions since we talked last Kids picked up new one recently named him Satan , it fits!!!!!!!!!!

Re: 1000 amp gfci breaker [Re: TNT_Tim] #204900 01/19/12 09:30 PM
Joined: Jul 2004
Posts: 783
LarryC Offline
Glad to help. Many other people here are much more qualified than I am.

Quick test. I assume this is a two coil contactor. One coil closes contactor, the second coil opens contactor.

____If it is safe to do so_____ isolate the neutral wire on the close coil. If the coil shorted to frame, it should still trip the main. If it still trips with the coil neutral wire disconnected, isolate the line side wire of the coil. If it still trips, then it sounds like the switch wiring is grounded.

good Luck.

Re: 1000 amp gfci breaker [Re: TNT_Tim] #204901 01/19/12 10:22 PM
Joined: Feb 2007
Posts: 12
TNT_Tim Offline OP
Thanks Larry, that is actually one of the other things I was going to do tonight, everything is in a trough underneath contactors, there are more there than these but this is the troublemaker. It hit me last night I saw a big blue wirenut in there with a whole lot of neutrals in it. I'm curious also if some has put lv and hv neutrals together. And you are correct sir, mechanically held open and close coils, but old GE style reverse wound so it's on the same core

Re: 1000 amp gfci breaker [Re: TNT_Tim] #204962 01/25/12 01:19 PM
Joined: Jul 2004
Posts: 783
LarryC Offline
Any updates?

Re: 1000 amp gfci breaker [Re: TNT_Tim] #205024 01/28/12 08:33 PM
Joined: Jan 2005
Posts: 354
pdh Offline
GFCI current sensors are apparently easily triggered by radio waves.

In an apartment I used to live in, the bathroom GFCI was apparently wired backwards. When wired backwards, it can still detect leakage current since that is a common mode AC current, so direction is not relevant. The problem with backward wiring is that opening the circuit does not disconnect power to the solenoid that opens the circuit. If for some reason the triggering current remains, a backwards wired device will keep operating the solenoid.

I found that 1 watt of RF in the amateur 2m band on a 1/4 wave or 5/8 wave antenna within 3 meters of the wiring leading to the backward GFCI would cause it to trigger, and it would keep buzzing loudly for as long as the RF was present.

RF can trigger these things. When the power wiring is acting as an antenna for nearby RF, it will be in common mode (both conductors conducting in the same direction at the same time), which will appear like leakage current. A simple rectification circuit to detect a voltage from the current transformer will operate over a large RF frequency range (e.g. from a few Hz to a GHz or more).

The arcing from the doorbell switch could be a long enough RF pulse to do this. Or the bell itself may be doing it.

RF filters that block common mode currents in the RF range (but not in power frequency range) could be used to stop such issues. Just be sure the filter used does not block 50-60 Hz common mode, or it could defeat the proper ground fault detection.

Re: 1000 amp gfci breaker [Re: pdh] #205051 01/29/12 07:40 PM
Joined: Jul 2001
Posts: 599
JBD Offline
First, GFCI is a specific term from both UL and the NEC, which is used to designate a Ground Fault protective device that is used to protect human life (i.e. 5mA trip).

Your 1000A main has a simple ground fault trip (GF or GFI or GFP). On service entrance equipment these devices typically have a minimum trip point of 200A. At the minimum setting these devices can easily trip before a 20A branch breaker will operate.

Most likely your lighting contactor is a mechanically held device, which means it has a separate circuit for turning Off. I would investigate this circuit for a GF. As pointed out by others, this may only occur after enough moisture has built up.

Page 1 of 2 1 2


2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
Portland, Oregon, United States
Posts: 404
Joined: March 2007
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
275,348 Are you busy
209,214 Re: Forum
196,517 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3