How many times can a breaker trip before it should be replaced?

[Pierre C Belarge]

I imagine that the fault current that a single pole 20 amp breaker is exposed to even in a commercial installation is likely to be fairly low with circuit impedance considered.

The size of the circuit breaker is not really the determining factor in this situation.
The location of the panel or enclosure housing the circuit breaker is part of what is important.
Such as the panel/enclosure being located just inside of the structure, and the transformer just outside of the structure. In cases such as this, there could be a large amount of available fault current to the overcurrent device regardless of its size.

 

[iwire]

The size of the circuit breaker is not really the determining factor in this situation.
The location of the panel or enclosure housing the circuit breaker is part of what is important.
Such as the panel/enclosure being located just inside of the structure, and the transformer just outside of the structure. In cases such as this, there could be a large amount of available fault current to the overcurrent device regardless of its size.

Pierre, please take the time to read the post carefully before answering. I know the size of the breaker does not directly have anything to do with the fault current available.

But the 100' + feet of 12 AWG between it and the fault sure does limit it, which is what I was saying.

with circuit impedance considered.

 

[bjp_ne_elec]

He means the line side and load side of the breaker, not the actual load. This is done with the breaker removed from the system. You are just meggering across the open contacts to test the breakers open pole insulation.

Zog - thanks for that clarification!

 

[Pierre C Belarge]

Pierre, please take the time to read the post carefully before answering. I know the size of the breaker does not directly have anything to do with the fault current available.

But the 100' + feet of 12 AWG between it and the fault sure does limit it, which is what I was saying.

I was clarifying your post, there are many who are not aware of what I posted. I am basing this train of thought on the comments and questions I receive in class.


It was not based on the other posts.

 

[ohm]

Pierre, please take the time to read the post carefully before answering. I know the size of the breaker does not directly have anything to do with the fault current available.

But the 100' + feet of 12 AWG between it and the fault sure does limit it, which is what I was saying.

Our chief inspector (also EE) told me the flags go up in resi work when he there is a pad mounted transformer feeding several homes closeby. Otherwise a 10 Kaic SE seems to work everytime. But, we still check them all out.

 

[Sharpie]

Did the OP say what the amps were at when the breaker would trip?
When you have a thermal/magnetic overload device (such as the breaker mentioned), how much sunlight or heat does it take applied to that breaker for it to trip at lower amps than rated for?

I would replace the breaker, but I'd still want to know why it was tripping.