I need a better understanding of a main panel gfi. Have a customer with a sqD 2000a 3p 4wire 480/277 main panel that is gfi. It is only about 5 years old and every few months or so at random it trips. Reset it and it is usually ok. No problems with any mechanical equipment triping breakers or blowing fuses at the same time. what kind of things would trip this gfi? john
main panel gfi
- Thread starter jociha
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: main panel gfi
Just because nothing else tripped does not mean you did not have a ground fault.
I don't understand the part about "usually ok". If it won't reset, it either means the thing is defective or the ground fault has not cleared.
I would be looking for patterns to narrow down what is going on.
Usually this indicates a ground fault of some kind.
Just because nothing else tripped does not mean you did not have a ground fault.
I don't understand the part about "usually ok". If it won't reset, it either means the thing is defective or the ground fault has not cleared.
I would be looking for patterns to narrow down what is going on.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: main panel gfi
The GFP is probably still set at the factory supplied minimum. If this is as low as 200A at .1sec, then it will trip before any branch OCPD can clear the circuit (a 20A breaker can usually hold 200A for 6 secs, or else they would trip on motor inrushes).
Has a coordination study ever been done to determine the proper setting of the ground fault function?
The GFP is probably still set at the factory supplied minimum. If this is as low as 200A at .1sec, then it will trip before any branch OCPD can clear the circuit (a 20A breaker can usually hold 200A for 6 secs, or else they would trip on motor inrushes).
Has a coordination study ever been done to determine the proper setting of the ground fault function?
- Location
- Logan, Utah
Re: main panel gfi
Check with the manufacturer for proper settings, also check with them for possible malfunction of the GFCI equipment.
I had a similar problem a few years ago with a Square D GFCI main breaker. The GFCI would trip for no apparent reason, we searched every panel, and piece of equipment for any sign of a ground fault. We called the Square D rep and asked if they could send a tech to check the breaker. They told us that it was improbable that the breaker was faulty, and that they would charge us a large fee to send out the service rep. When he arrive he found that indeed the breaker was faulty and installed a new one. Worked like a dream after that (By the way no charge
)
Chris
Check with the manufacturer for proper settings, also check with them for possible malfunction of the GFCI equipment.
I had a similar problem a few years ago with a Square D GFCI main breaker. The GFCI would trip for no apparent reason, we searched every panel, and piece of equipment for any sign of a ground fault. We called the Square D rep and asked if they could send a tech to check the breaker. They told us that it was improbable that the breaker was faulty, and that they would charge us a large fee to send out the service rep. When he arrive he found that indeed the breaker was faulty and installed a new one. Worked like a dream after that (By the way no charge
)Chris
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