ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Extension cords
by annemarie1. 09/25/18 06:06 PM
220/230/240V 60Hz Systems
by gfretwell. 09/23/18 02:50 PM
Inspection camera help
by petey_c. 09/22/18 07:52 AM
Motion detectors and dimmers
by gfretwell. 09/20/18 04:02 PM
Acronis Backup 2017
by gfretwell. 09/16/18 12:46 AM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
0 registered members (), 13 guests, and 17 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Return air wiring method #96031
10/31/05 10:05 AM
10/31/05 10:05 AM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
What are your thoughts about using a cable Listed as CL2R in the return air joist space of a residential occupancy? Is this acceptable by inspectors or should this be CL2P?


George Little
2017 / 2014 NEC & Related Books and Study Guides
Re: Return air wiring method #96032
10/31/05 02:00 PM
10/31/05 02:00 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,290
Estero,Fl,usa
Vote me "plenum".
Riser rating only has to do with flame spread, not toxicity of the smoke as far as I understand.


Greg Fretwell
Re: Return air wiring method #96033
10/31/05 08:22 PM
10/31/05 08:22 PM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Is the joist space in a residential occupancy considered to be a plenum?


George Little
Re: Return air wiring method #96034
10/31/05 09:24 PM
10/31/05 09:24 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,290
Estero,Fl,usa
I suppose it would all depend on how you ran the wire. Is it passing through at a 90 or running with the bay


Greg Fretwell
Re: Return air wiring method #96035
10/31/05 10:08 PM
10/31/05 10:08 PM
H
harold endean  Offline
Member
Joined: Feb 2002
Posts: 2,233
Boonton, NJ
Greg,

Here in some of my towns the building or fire inspector will fail a job if wire, RX or other, is run through any ductwork in a resi bldg. There is one job here I was looking at and th tin knockers "Panned" a whole main girder. and when they did that, they enclosed not only wires, but there was a large waste line. "Panning" is when the tin knockers put a flat piece of tin across the bottom of your 2 X 10's and they use that area to move air instead of using a piece of ductwork itself.

Re: Return air wiring method #96036
10/31/05 11:17 PM
10/31/05 11:17 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,290
Estero,Fl,usa
I think the answer is in 300.22(C)ex
Quote
Exception: 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.


When I first read George's note I was thinking about wires running down the stud bay <the riser ref in CL2R>.
If they simply cross the bay it is probably OK but YMMV with various AHJs
I have seen it go both ways in suspended ceilings and computer floors too.
All IBM interface and power cables after about 1994 were plenum rated (AKA "DP"), tan colored. The blue ones were riser rated and tolerated until we could swap them out but the grey (unrated) ones had to go.

In other than dwellings 725.61(A) would affect low voltage wire, no matter which direction it ran.
Quote
(A) Plenum. Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CL2P or CL3P ...


[This message has been edited by gfretwell (edited 10-31-2005).]


Greg Fretwell
Re: Return air wiring method #96037
11/01/05 01:07 AM
11/01/05 01:07 AM
G
George Little  Offline OP
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Greg nailed it. I was addressing the wiring installed with the air flow and the code reference 725.61(A) talks about cables in plenums, ducts and other space used for environmental air as needing to be Listed and labeled as plenum cable. the other reference is valid if you are installing cables perpendicular to the air flow.


George Little

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Potseal
Potseal
Saskatchewan
Posts: 264
Joined: February 2013
Show All Member Profiles 
Top Posters(30 Days)
Admin 13
Popular Topics(Views)
249,470 Are you busy
187,388 Re: Forum
176,728 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.029s Queries: 14 (0.004s) Memory: 0.9854 MB (Peak: 1.1389 MB) Zlib enabled. Server Time: 2018-09-26 06:51:05 UTC