I've calculated the service size for a new commercial building as 4000A. The owner wants to separately meter each of the five floors with utility meters, plus an additional utility meter for house loads. The load to each floor (and the house load) is 800A. Does the NEC permit the use of (6) 800A service disconnects (breakers) in a 4000A main switchboard, without the use of a 4000A main breaker?
Service Disconnects
- Thread starter msteiner
- Start date
- Status
More please. . . .
I'm not required to protect the 4000A bus at its ampacity, provided the calculated load doesn't exceed the combined rating of the six breakers? Can I assume that's why I don't need a main breaker? But the 800A breakers are essentially the next conveniently sized (i.e. rounded up) breaker for distribution to each floor. My calculated building load is 4000A, not 4800A.
o.k. yes (again) (230.71)
Correct, unless your local AHJ requires.
you can
Just make sure your calculated load on each breaker doesn't exceed your conductor.
In TN that project would rerquire stamped approved engineering drawings.
(assuming the bldg is over 5000ft?)
Last edited:
- Status