Electrical room fire rating

[patrox2000]

Hello everyone,

what should the fire rating of an electrical room containing a 112.5KVA dry type transformer be? is that in the NEC?

thanks.

 

[eprice]

A rating is not required by the NEC. See 450.21

 

[Volta]

As far as I know,that is not in the NEC, though some minimum distances are. That size transformer is the largest before the room construction type is referenced.

 

[patrox2000]

Thanks

Thanks

thanks very much.

 

[cowboyjwc]

Just FYI remember that most commercial is 1 hour rated by default (5/8 drywall, 2x4 stud, 5/8 drywall). Now of course there is more to it than that, but you get the general idea.

 

[eprice]

Just FYI remember that most commercial is 1 hour rated by default (5/8 drywall, 2x4 stud, 5/8 drywall). Now of course there is more to it than that, but you get the general idea.

I think this statement needs a little clarification. It is true that most commercial is built of materials that could be used in 1 hour rated construction, but I don't think it is true to say that most commercial is 1 hour rated. It is not rated unless the designers have called it out on the plans and it is consciously built to the details specified in a tested assembly from UL or other testing agency. The big difference that this distinction makes to the electrician is that if it is not rated he doesn't have to worry about using fire stops at his penetrations into or through the walls or ceilings just because it is built using 5/8" drywall.

 

[cowboyjwc]

I think this statement needs a little clarification. It is true that most commercial is built of materials that could be used in 1 hour rated construction, but I don't think it is true to say that most commercial is 1 hour rated. It is not rated unless the designers have called it out on the plans and it is consciously built to the details specified in a tested assembly from UL or other testing agency. The big difference that this distinction makes to the electrician is that if it is not rated he doesn't have to worry about using fire stops at his penetrations into or through the walls or ceilings just because it is built using 5/8" drywall.

And thus the statement, ".....there is more to it than that."

 

[patrox2000]

Thanks

Thanks

Thanks for the replies everyone. very helpful.

 

[WorkSafe]

When are transformers or other equipment need to be in vaults? Just the oil filled type...or? Just curious.

 

[Volta]

From memory only, not looking at a codebook, I think it is any transformer over 112.5 kVA, unless a Class 155 or higher insulation rating.

Dry-type, anyway.