# Outlets in plenums



## Mac (Jul 5, 2011)

AARRrrrrgggg  I'm going mental! Years ago the old pro taught me no electrical boxes may be insatlled in any plenum,

not no way, not no how.

Where might I find that provision now?


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## TimNY (Jul 5, 2011)

I think what you need is NEC 300.22(B):

_Equipment and devices shall be permitted within such ducts_

_or plenum chambers only if necessary for their direct action_

_upon, or sensing of, the contained air._


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## raider1 (Jul 5, 2011)

Are you asking about a space above a drop ceiling that is being used as a return air plenum?

If so the applicable section is 300.22© and if they are metal then they are allowed in this space.

300.22(B) only applies to Ducts Specifically Fabricated for Environmental Air not to return air spaces above a dropped ceiling.

Chris


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## north star (Jul 5, 2011)

** * * **



Since Mac asked specifically about " boxes " inside an

[ air ] plenum, how would you access them after

installation ( re: Article 314.29, 2008 NEC & Section

E3805.10, 2006 IRC ) ?



** * * **


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## Mac (Jul 6, 2011)

The offending 'boxes' are for outlets & switches serving the rooms. They are  in the cold air returns in a house. The floor & wall framing is used for the plenums.

A local third party electrical inspection agency approved the rough wiring install.


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## raider1 (Jul 6, 2011)

Mac said:
			
		

> The offending 'boxes' are for outlets & switches serving the rooms. They are  in the cold air returns in a house. The floor & wall framing is used for the plenums. A local third party electrical inspection agency approved the rough wiring install.


Then 300.22© would apply and the boxes would need to be metal and the NM cable could only pass through the cold air return perpendicular to the long dimension of the return air space.

Chris


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