ECN Forum Forums General Topics of the Trade General Discussion Area 700A Main Breaker nuisance tripping

Hi, this is my first post, happy to be on this forum.

The main breaker for our 3-phase/460v building power tripped on Friday and the Emergency Generator and ATS switched on. I noticed that the Genset out put display showed this: 468 v ,60hz , 715 amps total.

but each seperate phase measured around 235amps. is this enough to trip the breaker due to overloading?

I thought that a breaker marked 700 amps could hold 700 amps per pole?

thanks to all.

I am a little confused with how many amps you are drawing, I have never seen a generator with a "Total Amps" meter.

If you have 235 amps per phase then we would say the breaker has a 235 amp load.

Each pole of a 700 amp breaker is rated 700 amps but we do not call it a 2100 amp breaker.

A typical 700 amp breaker should not be loaded to more than 80% (560 amps per leg) for periods exceeding 3 hours. That is unless you have a 100% rated breaker, most are not.

The amps draw per leg was around 235 each. a=235amps, b=235amps, c=235amps

Thanks for the clarification.

Our Generator was installed a few weeks ago and it has a slick microprocessor display, with the Total amps reading.

This 700 amp breaker has a little switch assembly Called a "ground-censor" on the panel below the breaker that could be sensing a fault somewhere.

I'll post more details soon.