milwaukeebob
Electrical
- Jun 21, 2004
- 42
I have a question related to NEC 110.26(C)(2) and an existing electrical MCC room installation. The installation has an MCC with a 1200AF main incoming circuit breaker (CB) that is set at 800AT. The MCC is labeled and rated 1200A but set to trip at 800A. The upstream CB feeding this MCC main circuit breaker is also 800AT. By virtue of this, is it fair to say the MCC is "rated" 800A? or would the Code consider this "Rating" as defined by the 1200AF CB? This may seem nitpicky but I'm getting a bit hung up on the wording in NEC 110.26(C)(2) which defines the Entrance to and Egress from Working Space for Large Equipment "Rated" 1200 amperes or more. In the most literal sense, the equipment (MCC) is "rated" 1200A but it's essentially been derated to 800A. Any Thoughts?