# In Need Of Help



## scotch (Oct 17, 2013)

Looks like the main breaker trip was from ground fault condition...usual on that size of breaker there's a ground fault trip circuit. 
If you isolate downstream wiring after the first 7 ....does the lighting work and the breaker stay on line ?
Neutrals would be common to all circuits....so any line will read to any neutral normally .
You're going to have to follow the wiring thru to the last fixture ...who knows maybe someone lately added a circuit wrongly to the wiring and caused your problem ...ask your guys .


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## MikeFL (Apr 16, 2016)

Could be a bad ballast. Disconnect all the lights and reconnect them one at a time and see when the problem arises again.


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## wildleg (Apr 12, 2009)

resetting a tripped main willy nilly is not best practice.

some fellas are gonna come along into this thread and hand you your a$$.

Don't get all butt hurt about it, they are only going to be trying to teach you better safe practices.


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## telsa (May 22, 2015)

You're certain to stir up building management with trips as you dope this out.

1) Get an isolation transformer in your test scheme. Stop drawing line power directly off of the 480Y277 bus -- as it's protected by a GFI master C/B.

2) Said isolation transformer could take the form of a gen-set, too.

3) Solve and perfect the branch circuit -- entirely -- and then put the circuit back on the bus. ( ie the old breaker )


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## ScottyMintz (Feb 20, 2017)

I appreciate the help guys, I really do. I will give these things a try first thing tomorrow.

Thanks again


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## RePhase277 (Feb 5, 2008)

ScottyMintz said:


> I appreciate the help guys, I really do. I will give these things a try first thing tomorrow.
> 
> Thanks again


You were reading this 306 volts with the circuits off?


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## ScottyMintz (Feb 20, 2017)

Yes I was reading it with both circuits turned off and the wires disconnected from the contactor itself. That's what was really throwing me off.


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## PlugsAndLights (Jan 19, 2016)

What sort of meter? A low impedance meter would help to rule out 
floating/ghost voltage. 
P&L


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## RePhase277 (Feb 5, 2008)

Probably induced voltage. Your digital meter has such a high impedance it will read the capacitance of a long run. The reason it didn't appear between conductors of the same circuit is because they are connected to the load, which drains that capacitance.

In other words, it's ghost voltage. Use a Wiggy and it will go away.


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## scotch (Oct 17, 2013)

That's a poor electrical co-ordination you've got at your facility when a lighting circuit can trip the main breaker for the whole building . With that electronic ground fault built into the main maybe you need a 20A ground fault breaker on the lighting circuit so it trips instead on the main ....should be able to get 30mA trip at least ; and check the main breaker settings so it's trip delayed . Or you put in an isolation transformer on those lighting circuits


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