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#84005 - 02/25/03 03:34 PM Plenum Cables
buckeye Offline
Junior Member

Registered: 02/25/03
Posts: 1
Loc: cincinnati, ohio usa
Can Plenum cables be installed inside ducts

2014 / 2011 NEC & Related Books and Study Guides
#84006 - 02/25/03 03:40 PM Re: Plenum Cables
HotLine1 Offline


Registered: 04/03/02
Posts: 6792
Loc: Brick, NJ USA
Welcome to ECN
To the best of my knowledge.NO cable (wiring) can be installed within ducts. I do not have my NEC handy, so this is from experience and memory.

#84007 - 02/26/03 09:55 AM Re: Plenum Cables
Big A Offline

Registered: 01/22/03
Posts: 47
Loc: Lynchburg, VA
Hello All,

I don't have my 2002 book handy but 1999NEC 300-22 says no unless the wiring is needed for equipment inside the duct. The exception to 300-22 says "This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces" The way this was explained to me by my AHJ was that you cannot run wires in metal ducts but in homes with the above mentioned spaces used as ducts, wiring can be ran perpendicular to the length of the space.

#84008 - 02/26/03 02:18 PM Re: Plenum Cables
SvenNYC Offline

Registered: 08/19/02
Posts: 1685
Loc: New York City
Then why is it called "Plenum" cable?

I thought "plenum" was another word for duct.

Isn't there something called plenum-rated cable? *confused*

#84009 - 02/26/03 02:32 PM Re: Plenum Cables
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I think its a hold over from when we called the space above a suspended ceiling a "Plenum" when it was used for return air for HVAC, now that space is called "Other Space for Environmental Air" 2002 NEC 300.22 (C)

The FPN makes this clear

[This message has been edited by iwire (edited 02-26-2003).]
Bob Badger
Construction & Maintenance Electrician


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