ECN Forum Forums General Topics of the Trade General Discussion Area 1000 amp gfci breaker

John,

I too saw a ballast knock out a 1600 amp main GFPE breaker and take out the whole building. Now I make sure the EC's set the GFPE setting correctly.

Hello again,
Well I found a bad fixture that was causing it to trip. But it has once again started it's shenanigans. As I had stated in an earlier post it is not a GFCI breaker but a GFP. After doing some research and talking with some engineers these breakers do not have a set trip value but rather rides inside a bubble if you will that move up and down with the current passing through it, if the ground fault moves outside this bubble it trips. So my theory is that they are on the verge or riding the line of the bubble all the time so it is easy to trip. Also distance plays a huge role in this as well, GFP breakers max trip is with conductors leaving MDP about 60 ft away, the longer the conductors are out to sub panels the more this "bubble" shrinks. This pool panel has prob 250 ft of feeder conductor back to MDP. Just thought I would give a quick update, going back tonight to see if I can another bad fixture.

BTW, these fixtures really aren't bad, as in not working , but probably starting to break down or turning off collapses the magnetic field and induces enough current to trip the main

You stated in your second post that when you turned off the fixtures but operated the lighting contactor, the main breaker still tripped. Did you find and fix the contactor related issue?

Hey Larry,
Thank you, I did replace the contactors but still had a problem in one the lighting circuits , just left site and here is what I found:

Going back to MDP I took off all bottom covers and started looking for anything unusual on grounding side of the system. I found a ground wire coming from a bank of power factor correcting capacitors grounded on the neutral bus bar and not the ground bar, this ground was attached on the load side of the neutral sensor on the GFP. Shut power off and moved it to ground bar, current on neutral bus immediately dropped by 200 milliamps. I then cycled lighting 5 times, waiting in between to let them achieve full brightness and GFP never tripped. My theory is that one or more of the capacitors is starting to fail and was leaking current onto the ground wire, which was tied to the neutral bus, causing an imbalance and was being sensed by the ground fault circuitry and causing the breaker to trip. Does that sound plausible to you

Again thanks for your input, stay safe

Yes it does sound plausible.

So you think you had three sources of ground current leakage? Lighting contactor, failing fixture, and the miswired PFC capacitors ground lead.

Only a theory, but I think there is a cumulative effect going, lots of little things, each small but adding together they are pushing the envelope of the trip settings. So I changed my thinking to looking for many small things instead one large problem. Funny thing is I haven't fixed the one light I took down yet, just about tempted to go hang it back up just to see what happens now

Any idea what the trip point is, when everything is running?

I'll start with this is a GE High Pressure Contact Ground Fault Protected Switch, that's how GE refers to it.
As was explained to me from GE the trip setting is a variable number , really shouldnt go over 1000 milliamps but can be as low as 100 milliamps. So that makes it really clear this is in no way intended or designed to protect personnel, it is to protect equipment only. It is a product of voltage at a given time, current flowing at a given time, voltage drop and resistance. He said if I can give him these numbers at a given time then the trip can be calculated at that instance. I can only assume the window has to be calculated at a 5% voltage drop which is required not to exceed by the NEC. Of course resistance on the system and the voltage and current will play into that, and since the current will fluctuate I can see that number being a variable. He did say maximum trip is calculated with feeder conductors being no longer than 60 ft from source, little confused why the continuation of branch circuits wouldn't affect it. I guess to answer your question would be a no, lol
All in all I'm kind of impressed this is being done real time on a 30+ year old distribution breaker.