Fire Rating on Elec/IDF Room

[DeLiRiuM]

1. Does an electrical room need to be 1 hr fire rated regardless of whether or not it has a transformer? From my initial reaction, according to 450.21(A) it leads me to believe that it wouldn't necessarily require it, but i might be missing something...

2. Does an IDF room need to be 1 hr fire rated?

 

[charlie b]

There is no such thing as an electrical room, or an IDF for that matter, as far as the NEC is concerned. Once in a while we have to put things into a "vault." But for the most part, we don't need a room for any of our equipment. You can put everything, from the service equipment to branch circuit panels, in a public corridor, if you wanted, and if the architect would allow it. You can even put it all outdoors, if you get equipment rated for that environment.

 

[ronmath]

Charlie is correct. You must be thinking of transformers over 112-1/2 KVA per 450-21(B). Most of the Dry type transformers today though have class 155 or higher insulation so fall under exception 2 (or exception 1 with proper barriers.