Technical FAQs

Ask a Question

Can transformers be placed in a plenum chamber? Or does Square D offer plenum rated transformers?

Issue:
Can transformers be placed in a plenum chamber?  Or does Square D offer plenum rated transformers?

Product Line:
Low Voltage Transformers.

Environment:
Products sold in the United States.

Cause:
Application.

Resolution:
A transformer is not allowed in a plenum chamber, while it may be allowed in other space used for environmental air, such as a drop ceilling.

Per 2002 NEC 300.22(B) for ducts or plenums used for environmental air, ``... Equipment and devices shall be permitted withing such ducts or plenum chambers only if necessary for their direct action upon, or sensing of, the contained air. ...`` Thus, as a transformer doesn`t have anything to do with the air, it is not possible to have a plenum rated transformer.

Per 2002 NEC 300.22(C)(2) for other space used for environmental air, ``Electrical equipment with a metal enclosure, ... shall be permitted to be installed in such other space unless prohibited elsewher in this Code (NEC 2002).`` And per 2002 NEC 450-13(B) for hollow space installations (which other space used for environmental air would apply) ``Dry-type transformers 600 volts nominal, or less and not exceeding 50kVA shall be permitted in hollow spaces of buildings not permanently enclosed in by structure, provided they meet the ventilation requirements of 450.9 and separation from combustible materials requirements of 450.21(A). Transformers sow installed shall not be required to be readily accessible.`` Thus, low voltage dry type distribution transformers up to 50kVA may be used in a drop ceiling as long as not prohibited by local code.

If there are further questions, consult the local AHJ.


CTA-ID : 2012491
Was this helpful?
What can we do to improve the information ?