[WillK]

Around 3 months ago, I began using my new subpanel for circuits in the kitchen and upstairs bedrooms. The subpanel gets power from 2 gage aluminum and has a 60 amp breaker on the main panel. The 60 amp panel has tripped twice in the last 10 hours, no other breakers tripped on the subpanel.

Last night we were running a dishwasher, washing machine, a TV and some small lights upstairs off the subpanel. This morning it tripped while running some small lights upstairs and a toaster.

Again, no breakers tripped, neither did any AFCI or GFCI trip and I think everything on the panel has either AFCI or GFCI.

It sounds to me that the 60A breaker that is tripping must be bad, but I wanted to double check here to make sure in case I should be checking anything else.

 

[user1007]

Could be a loose neutral wire or something simple. Best have an electrician check it out if you are not sure.

 

[HouseHelper]

It's not a neutral problem, that would have no effect on the breaker.
Most likely it is the breaker, either overheating or just getting weak. If you replace it, check carefully for pitting and burning on the bus where it is connected. A bad connection will cause damage to the breaker and bus.

 

[a7ecorsair]

Around 3 months ago, I began using my new subpanel for circuits in the kitchen and upstairs bedrooms. The subpanel gets power from 2 gage aluminum and has a 60 amp breaker on the main panel. The 60 amp panel has tripped twice in the last 10 hours, no other breakers tripped on the subpanel.

The main has a 60 amp breaker and the sub has a 60 amp breaker and it is the sub panel breaker that is tripping, correct? Was this panel brand new when it was installed? Is the breaker in the sub panel bolted to the bus bars or is snapped onto the bus bars (back fed)? You could start by turning off the main panel breaker - make sure there is no power to the sub, and then make sure the feed wires are securely fastened to the breaker and that the breaker is securely fastened or snapped to the bus bar. A poor connection could be causing the breaker to heat up.

 

[WillK]

The main breaker in the subpanel is a 200 amp breaker and is not tripping. The 2 gage cable between the main panel and the subpanel connect to a 60 amp breaker in the main panel, this is the breaker that is tripping. The main panel has a 100 amp main breaker that is not tripping.

The main panel is somewhere around 15 years old or less, everything else described above is new. The subpanel is new, the 2 gage cable to it is new, the 60A breaker is new.

I haven't had time to even open any panels yet, the breaker tripped last night and I just wrote it off at the time as maybe the combined load of everything that was running was too much and it was time to accelerate the plans to upgrade to 200 amps and move the service entrance to the 200 amp panel, but this morning when it was tripped by basicly a toaster and a few lights while getting ready for work that's what told me maybe something's wrong with equipment and I wanted options to check when I got home.
So thanks, I'll check the connections to make sure they're tight at the breaker and the subpanel.

 

[mpoulton]

This could be a loose connection at the breaker, either where the breaker attaches to the bus or where the #2 Al connects to the breaker. Resistive heating at these connections can cause the breaker to thermal-trip. So, remove the breaker and look for heat damage on the terminals and bus connectors. Remove and re-torque the connections to the #2 Al, using anti-oxidant, and reinstall the breaker in the panel, making sure it feels tight on the bus when you install it. If it doesn't seem right or has visible heat damage, replace the breaker.

 

[dmxtothemax]

Dont forget to consider that there could be an intermittant short somewere, posssibly caused by a damaged cable.
But first place check all connections,
Then check breaker,
Substitute the breaker.