petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
maybe not a NEC question, but on a pretty regular basis I get drawings (sometimes just sketches) for systems showing a main CB and another slightly smaller CB protecting a motor. In the latest case, It was a 125HP motor that had a 250A main CB with a 225A CB feeding a soft start. There are some misc small loads the main CB is also feeding, but I am having a hard time figuring out why anyone would spend the money on the 225A CB, as it appears to be redundant to me.
Is there some reason that I might be missing that would make a second CB useful in some way. It is not like they would ever need to shut off the 225A breaker and leave the other loads on.
Just curious if I am missing something obvious or it is just something they are doing for no good reason.
Is there some reason that I might be missing that would make a second CB useful in some way. It is not like they would ever need to shut off the 225A breaker and leave the other loads on.
Just curious if I am missing something obvious or it is just something they are doing for no good reason.