Maybe this is the problem.

[ptonsparky]

My wife's Aunt wanted to talk to me at the end of their phone conversation. She relayed the story of her main breaker tripping and the neighbor suggesting she call an electrician if it happened again. I suggested we look sooner.
View attachment 14687
Not quite typical, but we've all seen PP connections fail.

View attachment 14688

Maybe this is why the main tripped.

 

[jumper]

Breakers are fine, just put in a ground rod and you good to go.

 

[Jraef]

My wife's Aunt wanted to talk to me at the end of their phone conversation. She relayed the story of her main breaker tripping and the neighbor suggesting she call an electrician if it happened again. I suggested we look sooner.
View attachment 14687
Not quite typical, but we've all seen PP connections fail.

View attachment 14688

Maybe this is why the main tripped.

The picture isn't clear, but did they not use the ties for the lugs for that and only terminated to two of the lugs instead of all 4?

 

[ptonsparky]

Those are two 2-pole 60 amp 1ph circuit breakers for her electric heat. The connections on one wire of each CB failed badly enough to burn through the side of each CB until the two legs started arcing and sparking enough to trip the 150 amp main.

 

[gadfly56]

Those are two 2-pole 60 amp 1ph circuit breakers for her electric heat. The connections on one wire of each CB failed badly enough to burn through the side of each CB until the two legs started arcing and sparking enough to trip the 150 amp main.

Simultaneous failure on two breakers, or one burned through to the other?

 

[ptonsparky]

Simultaneous failure on two breakers, or one burned through to the other?

I wouldn't bet the farm on one or the other scenario.

 

[Jraef]

Ah, you had said "main" earlier, so I thought maybe that was one of those 4P main breakers where they parallel two smaller ones.

 

[jumper]

Ah, you had said "main" earlier, so I thought maybe that was one of those 4P main breakers where they parallel two smaller ones.

Was that or is that legal? No common trip?

Main breakers do have common trip, no?

 

[winnie]

Not legal as a field install, but I have seen '4 pole' breakers (2 poles in parallel for each leg) as part of a listed panel assembly.

-Jon

 

[ptonsparky]

I looked at the breakers thinking the lugs had loosened enough so they had contacted each other enough to cause the arcing. Closer exam showed the lugs do not move enough for that to happen. Must have been the carbonized material that fell between the two.

 

[norcal]

Ah, you had said "main" earlier, so I thought maybe that was one of those 4P main breakers where they parallel two smaller ones.

Cutler-Hammer is one of the companies who copied ITE, in that regard,