AC Breaker tripping

In my main panel (200 amp) I have a 100 amp breaker that feeds a sub panel for my two AC unit's aux power. They are 60 amp breakers for each of the Aux units. When it is very cold and both ACs are on and require the Aux coils it will frequently trip the sub panel 100 amp breaker in my main panel.

If the wire from the main to the sub is #4 or bigger can I change out the 100 amp breaker for a 125 amp breaker?

My panel and breakers are Gould/ I-T-E brands.

Thanks

 

95a is max foe #4 even at the 90° listing. Even less at the 60° rating which may apply in this case depending on the rating of the connections. First you need to check the actual amp draw with a clamp on amp meter. It could just be a weak breaker.

 

First of all, A-C units don't normally run in the winter. It sounds as if you have two heat pumps with 10 KW auxiliary electric strip heat for each one. The 100 amp breaker should probably be changed to 125 amps, but the feeder must be big enough for 125 amps.

No, you cannot change from 100 to a 125 amp breaker if the feeder is a #4. A #4 copper conductor can be used as a residential 100 amp feeder, but that's actually more than the conductor is rated for. You'll need a minimum size of #2 copper or 1/0 aluminum for a 125 amp residential feeder. My opinion is based upon an assumption that you have 10 KW auxiliary electric strip heat with each heat pump, you need to verify exactly what you have.

 

I think you would be better off running a new 60 amp feed off the 200 amp panel and re-feeding one of the heat pumps. Getting one of the 60 amp loads off the 100 amp panel will solve your problem, and be cheaper to install.