Wiring through central air return?


  #1  
Old 02-29-04, 03:04 PM
Jason
Visiting Guest
Posts: n/a
Wiring through central air return?

I am wiring a finished basement to put a few new outlets. I can't get the fish tape through the framed in duct work, and was wondering, is there anything wrong with putting a small hole in the duct work and fishing it through, because it is a clear path to where I need to go.

Any help is appreciated.

Jason
 
  #2  
Old 02-29-04, 04:21 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Upvotes: 0
Received 1 Upvote on 1 Post
Not quite sure what you're trying to do. It is legal to run a cable across the duct the short way (i.e., a couple of feet), but not legal to run a cable through the duct (in the same direction that the air flows). Of course, to run a cable across a duct you would clearly have to put holes in it. Caulk the holes.
 
  #3  
Old 02-29-04, 05:13 PM
noxx
Visiting Guest
Posts: n/a
Restrict your wiring method to type MC cable per NEC 300.22 and be sure to adequately close any openings you create.
 
  #4  
Old 02-29-04, 08:01 PM
Jason
Visiting Guest
Posts: n/a
Running wiring

I am trying to run new 12/3 cabling to provide new outlets in a area of the basement that doesn't have outlets. The basement is finished, and I want to minimize any drywall work. There is an air return from the main level that is taking the same path that the wiring needs to take. I have been trying to fish along the duct work, but there is too much blocking. I figure I can just drill a small whole in the duct (air return duct) on each end and fish the wiring through the duct.

Is there any danger in doing this?

I figured I would just put a bushing on each end to prevent any cuts in the sheathing, and caulk any remaining gaps.

If anyone sees anyhting wrong with this, please let me know.

Thanks, Jason
 
  #5  
Old 02-29-04, 09:07 PM
rbad
Visiting Guest
Posts: n/a
It should be just fine for a very short run, but, as the other poster noted:

Make sure to utilize MC or EMT for the run.

(you do NOT want to add a flammable material into that return
air duct) also.. make sure to seal each opening around the bushings on each side with a sealant -- I would probably just use hi-temp silicone, but am unsure about the code on that)


Worst case scenario, (assuming that you are using 12/3 NM)simply install a METALLIC junction box on each side of the duct and run greenfield between the boxes.)

Just insert the 12/3 into the first box, strip down the outer jacket for the length needed for the greenfield run + the amount necessary in each junction box. This eliminates the need for splices that aren't necessary. Just make sure to bond the bare copper ground to the box on each side. (therefore ensuring that the greenfield gets properly bonded to ground).


Hopefully, a licensed electrician here can validate my instructions above...
 
  #6  
Old 02-29-04, 09:24 PM
noxx
Visiting Guest
Posts: n/a
Greenfield (metallic flex) is not allowed inside a plenum space with the exception of a short whip to feed a device designed to mount inside the plenum (duct smokie).

The allowed wiring methods are MC and MI cable. As MI cable is.... costly, to say the least, 12/3 MC would be the approved method.
 
  #7  
Old 02-29-04, 11:53 PM
rbad
Visiting Guest
Posts: n/a
Thanks for the correction ....

Sorry for giving advice that was not correct !!
 
  #8  
Old 03-01-04, 08:24 AM
Jason
Visiting Guest
Posts: n/a
Thanks.

Each run is only about 10 feet. I will use your advise. Thanks. Jason
 
  #9  
Old 03-01-04, 03:48 PM
resqcapt19
Visiting Guest
Posts: n/a
Standard MC cable is not permitted in ducts. Only the MC that has a smooth or corrugated impervious metal sheath can be used. The standard interlocking armor type of MC cable is not permitted for that application. See 300.22(B).
Don
 
  #10  
Old 03-01-04, 04:59 PM
J
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 7,895
Received 477 Upvotes on 393 Posts
You are not permitted to run lengthwise down a duct unless you use cable that won't burn. Data cable is called FT6. Not sure what you call it in electrical wire. You are permitted to cross a duct with normal cable.
You don't want a burning cable(usually toxic) to gas the occupants.
 
  #11  
Old 03-01-04, 05:46 PM
noxx
Visiting Guest
Posts: n/a
You are permitted to cross a duct with normal cable.
Joe would you cite a source that allows this? As Don and I have pointed out, the governing article here is 300.22, which disallows nm cabling in a plenum regardless of distance.
 
  #12  
Old 03-01-04, 05:51 PM
resqcapt19
Visiting Guest
Posts: n/a
Joe,
If this was a 300.22(C) application, then I would agree that you could cross this space perpendicular to the long dimension of the space, but it is my opinion that this is a 300.22(B) application and you are not permited to run nonmetallic power cabling in this space.
Don
 
  #13  
Old 03-01-04, 06:41 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Upvotes: 0
Received 1 Upvote on 1 Post
By the title of the post, Jason referred to this as "return" space. Most return space would be 300.22(C) space, but I must admit that we really don't have a good enough description of this space to judge.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: