Mr. Chippers
Member
- Location
- Illinois
- Occupation
- Electrical Engineer
I have an existing circuit I want to use and replace the existing motor load with new. The circuit includes a 400A ATS, fed from 400A breakers on both the normal and emergency side. All feeders are 500kcmil. My new motor load is (321 MCA, 500A MOCP, 271 RLA). I'd assume the FLA would be 321 MCA x 80%, which equals 257 FLA.
I think I'll have to replace the breakers with at least 450A's, likely 500A. But my question is would I have to replace the 400A ATS as well? My FLA is well below what the 400A ATS can handle. But the breaker size will now exceed the ATS size, but that's only to accommodate the motor startup current.
I think I'll have to replace the breakers with at least 450A's, likely 500A. But my question is would I have to replace the 400A ATS as well? My FLA is well below what the 400A ATS can handle. But the breaker size will now exceed the ATS size, but that's only to accommodate the motor startup current.
