Plenum Ceiling/ Transformer installation

[Fordean]

Question,

In office building I have to Step down 480 to 120/208. And mount transformer in ceiling 15 kva. Ceiling is plenum rated. Is their a plenum only transformer? (Encapsulated may work?). I called transformer company. Jefferson. And they dont have nothing?

 

[infinity]

Where are you seeing a requirement for a plenum rated transformer? Here's what the NEC says:

450.13(B) Hollow Space Installations. Dry-type transformers 600 volts, nominal, or less and not exceeding 50 kVA shall be permitted in hollow spaces of buildings not permanently closed in by structure, provided they meet the ventilation requirements of 450.9 and separation from combustible materials requirements of 450.21(A). Transformers so installed shall not be required to be readily accessible.

 

[Fordean]

Plenum

Plenum

I did not see any requirements. I figured all the trouble of making a ceiling plenum rated with equipment wiring etc. Ventilated type might be a issue. I seen them doing it before, Installing ventilated in plenum. But I am double checking. Thanks for the reply. Did help.

 

[steve66]

Also see 300.22(C)(2) which says equipment with a meatal enclosure may be installed in spaces used for enviromental air.

also note that the NEC definition of a "plenum" space doesn't quite match the common use of the word, which is why 300.22 C applies, and not 200.22 B.

Steve

 

[Fordean]

Thanks

Thanks

Very much for the direction and information, Like this site very much

 

[sandsnow]

Don't forget the Mechanical Code. Your local AHJ can accept or reject based on that.

We accept xfmr's above T-Bar when it is a "plenum". Your AHJ may not.