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» ICC Bulletin Board » Code Chat » Electrical Codes » Plenum rated.

   
Author Topic: Plenum rated.
1crazycajun
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Are electrical outlets and neon transformers allowed in a plenum rated ceiling ? I have had several different interpretations on this matter. Any help is greatly appreciated.

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1CrazyCajun

Posts: 8 | From: Grant, Oklahoma | Registered: Feb 2009  |  IP: Logged
fatboy
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No, 300.22

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1997 FLSTF

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Richard Haskins
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300.22(c) seems to be the section that applies to the space above a ceiling used as a plenum and I see no language that would prohibit an electrical outlet or a transformer as long as the housing is made of metal 300.22(c)(2)

I would have to say these items are permitted.

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Electrical Contractor & Code Enthusiast.

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raider1
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quote:
300.22(c) seems to be the section that applies to the space above a ceiling used as a plenum and I see no language that would prohibit an electrical outlet or a transformer as long as the housing is made of metal 300.22(c)(2)

I would have to say these items are permitted.

I agree.

Chris

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"I'm better than dirt. Well, most kinds of dirt, not that fancy store-bought dirt... I can't compete with that stuff."

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fatboy
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300.22 (C)(1) Wiring Methods. The wiring methods shall be limited to totally enclosed, nonventillated, insulated busway having no provisions for plug-in connections ...........

Am I mis-reading this?

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Arguing with an inspector is like wrestling with a pig in mud.....
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fatboy
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600.21 (F) ............Ballasts, transformers, and electronic power supplies installed in suspended ceilings shall not be connected to the branch circuit by flexible cord.

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Arguing with an inspector is like wrestling with a pig in mud.....
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raider1
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quote:
300.22 (C)(1) Wiring Methods. The wiring methods shall be limited to totally enclosed, nonventillated, insulated busway having no provisions for plug-in connections ...........

Am I mis-reading this?

the provisions for plug-in connections applies only to insulated busway.

quote:
600.21 (F) ............Ballasts, transformers, and electronic power supplies installed in suspended ceilings shall not be connected to the branch circuit by flexible cord.

Correct, you can't install flexible cord above a suspended ceiling.

The original posted never mentioned flexible cord, just a receptacle installed in a suspended ceiling and a neon transformer. The NEC would permit either a receptacle or a neon transformer to be installed above a suspended ceiling used for environmental air provided that they are installed in metal enclosures or non-metallic enclosures listed for the purpose.

Chris

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"I'm better than dirt. Well, most kinds of dirt, not that fancy store-bought dirt... I can't compete with that stuff."

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fatboy
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Sorry, zeroed in on the "plug-in". Always learning.

As far as 600.21, I made the leap on my own, if you are asking about a receptacle, and a piece of equipement....... I made the assumption of cord and plug connected.........oh well

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Arguing with an inspector is like wrestling with a pig in mud.....
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raider1
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No problem fatboy, we are all here to learn.

Chris

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Pierre Belarge
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The NEC has changed in the last couple of code cycles, so has the way the term "plenum" is used.

Years ago, the use of the ceiling as a plenum was quite common, today it is not nearly as common, actually it is rare.

So, I believe we need to discuss what is a plenum ceiling as per the OP.

1. Does the OP mean the ceiling is being used as a plenum?
or
2. Is the ceiling being used for "environmental air"?


Take a look at the definition of plenum in Article 100.

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Instructor, Inspector, Industry Advocate

Posts: 82 | From: Westchester County, NY | Registered: Feb 2007  |  IP: Logged
Builder bob
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good point pierre - I beleive that building ocde terminology, Mechanical COde teminology, and the elctrical code terminaology all have differnet definitions of a plenum. For example, every HVAC system does have a plenum even if the returns are hard ducted from the return grills to the unit itself.

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klarenbeek
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Bob, you're right that different codes have different defenitions for a plenum. In the IMC a plenum is "An enclosed portion of the building, structure, other than occupiable space being conditioned, that is designed to allow air movement, and thereby serve as part of an air distribution system." This doesn't include ducted portions of the system that are often referred to as plenums within the trade, such as the "plenum" box on top of a furnace. Code considers this duct, not a plenum. I know IMC considers a lot of areas plenums that NEC does not, such as above ceiling or below floor spaces used for air movement. In our jurisdiction we occasionally run into issues where something meets electrical code but not mechanical, often in underfloor plenums in IT rooms (IMC makes no consideration for IT rooms). Wiring in any space used for air movement has to be plenum rated, and combustible electrical equipment has to be UL 2043 listed to be allowed in what IMC consideres a plenum
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Builder bob
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Thanks for the technical aspects that may be lacking.....And you see (clarified) the point I was trying to make.

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Can you build to minimum standards? FWIW - MCP, CBO, CPE, CI, CFPE, ASCET
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wwebb
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The code does not allow flexible cords above a ceiling or in concealed spaces. What else would you use to plug into a receptacle???
Ballasts and transformers installed in these spaces are typically hardwired to the box, and some are even within an enclosure.

A plenum is any space (duct or above ceiling or in a stud space) that is used to convey environmental air (air that you and I will breathe in our environment) other than the actual room area. You cannot put any combustible materials in these spaces unless they are listed for the application.

The receptacle should not be permitted in this location.

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Wayne Webb
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Building Plans Examiner

Posts: 406 | From: California | Registered: Sep 2004  |  IP: Logged
Jim Shorts
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You can plug in a class 2 power supply and use CL2 cables on the load side of the power supply to power toilet flushers. Happens all the time.
Posts: 2 | From: Florida | Registered: May 2009  |  IP: Logged
   

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