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Old 04-12-2007, 11:51 PM   #16
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Running network wiring in a cold air return vent?


Thanks for all your advice and especially, professional advice from jwhite.

I don't claim to be a professional or certified contractor, just simply a do-it-yourselfer, which is why I went into such graphic detail about my question. Sometimes it's easier to explain it in 'baby' terms so that there are no misinterpretations. I was not intending on giving anyone a lesson in HVAC systems.

Thanks

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Old 04-13-2007, 10:48 AM   #17
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Running network wiring in a cold air return vent?


Article 830.154(B) in the NEC states that plenum rated network cable (type BLP or CMP) IS allowed in ducts or plenums for low power, network powered broadband communication cabling.
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Old 04-13-2007, 11:06 AM   #18
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Running network wiring in a cold air return vent?


I also concur that the wires should be kept out of the duct if they are straight networking wires. Is there anything from preventing you from simply running the wires through the walls other than it is just a bit more work. My house had zero networking and zero coaxial wire run anywhere when I bought it. I ran network cable and coaxial cable through the whole house through the walls fromt he attic down. Originating at a 3db forward gain, 8 output drop amplifier. It took a little bit of time but I was able to locate good locations to drop the lines down between studs by following the existing receptacle wiring. I didn't need to repair or patch a single wall. However, its really not much of a problem if you do, short of matching paints... I guess my point is, my opinion is to take your time and do it right. You live in your house, its worth not cutting corners.
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Old 04-13-2007, 04:57 PM   #19
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Running network wiring in a cold air return vent?


Quote:
Originally Posted by HouseHelper View Post
Article 830.154(B) in the NEC states that plenum rated network cable (type BLP or CMP) IS allowed in ducts or plenums for low power, network powered broadband communication cabling.
I agree that they are. If they are needed for the proper operation of the Air handling system. I do this every day for a living. I am an HVAC controls contractor.


(B) Ducts, Plenums, and Other Air-Handling Spaces.
Cables installed in ducts, plenums, and other spaces used for environmental air shall be Type BLP. Type BLX cable installed in compliance with 300.22 shall be permitted.

300.22 (B)
(B) Ducts or Plenums Used for Environmental
wiring methods consisting of Type MI cable, cable employing a smooth or corrugated impervious
sheath without an overall nonmetallic covering, metallic tubing, flexible metallic tubing, intermediate conduit, or rigid metal conduit without an nonmetallic covering shall be installed in ducts or specifically fabricated to transport environmental metal conduit shall be permitted, in lengths
1.2 m (4 ft), to connect physically adjustable and devices permitted to be in these ducts chambers. The connectors used with flexible shall effectively close any openings in Equipment and devices shall be permitted within or plenum chambers only if necessary for their upon, or sensing of, the contained air. Where devices are installed and illlumination is necessary facilitate maintenance and repair, enclosed gasketed- luminaires (fixtures) shall be permitted.

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Old 04-17-2007, 03:42 PM   #20
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Running network wiring in a cold air return vent?


Can I place PVC pipiing in the cold air return and run the wires through the pvc pipiing? My cold air return is enclosed by drywall on the left and right side, and by 2x4 on the top and the bottom is open to the basement. I would make the hole to the for the pvc piping as close to the size as the PVC piping(hopefully I can make a hole the same size) so there are no gaps. Your help would be greatly appreciated.

Last edited by burdman; 04-17-2007 at 04:19 PM.
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Old 04-17-2007, 07:54 PM   #21
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Running network wiring in a cold air return vent?


Polly vinyl chloride conduit gives off chlorine gas when it burns. It is about the worst thing you can put in a duct.
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Old 04-18-2007, 08:11 AM   #22
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Running network wiring in a cold air return vent?


You do not have access from above??
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Old 04-18-2007, 08:38 AM   #23
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Running network wiring in a cold air return vent?


I can go around the cold air return. I just did not want to do it that way but it looks like it is the only option I have. I will create a channel with PVC piping for the wires around the cold air return. I think this will make it easier later on if I have to run more wires.
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Old 04-18-2007, 11:44 AM   #24
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Running network wiring in a cold air return vent?


I'll say again: plenum (-P) rated cable for communication systems (Article 800) and low-power network systems (Article 830) is allowed in a cold air return (plenum space).

Article 90.3 states that NEC Chapter 8 covers communication systems and is not subject to the requirements of Chapter 1-7, except where the requirements are specifically referenced in Chapter 8.

800.154(A) states that cables installed in ducts, plenums, and other spaces used for environmental air shall be Type CMP. It also states that other types of communication wiring may be installed, if done in compliance with 300.22.

The first sentence of 830.154(B) states that cables installed in ducts, plenums, and other spaces used for environmental air shall be Type BLP. The second sentence refers to Type BLX cable, not BLP.

Is it confusing and ambiguous? Of course, it is the NEC. But based on what is in the 2005 codebook, it is permissible to use plenum rated communication and low powered network cable in a duct or plenum.
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Old 04-18-2007, 12:22 PM   #25
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Running network wiring in a cold air return vent?


Say I do decide to run the wires in the cold air return. I will need to make a hole in the 2X4 that is at the top of the cold air return. I will then need to make another hole just underneath the grill(still within the cold air return) to have the cables exit. I am not to worried about the hole underneath the grill but as for the on I am making in the 2X4 at the top of the cold air return. Do I need to seal it with something so no air is pulled in? If so, what can I use? I will post pictures tonight if it may help.
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Old 04-18-2007, 02:09 PM   #26
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Running network wiring in a cold air return vent?


You will need to seal both penetrations with fire caulk, available in tubes for a caulk gun from a good hardware or big box store.
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Old 04-19-2007, 08:52 AM   #27
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Running network wiring in a cold air return vent?


If you have access to drill through the top plate and you dont' mind cutting the wall, why don't you avoid the cold air return alltogether and just simply fish the cable inside the wall? If you cut a hole in the bottom of the wall - where you would place an "old work" electrical box and a coaxial face plate afterwards, and drill through the top plate above, as long as you

a. Drill and cut within the 14.5" space between the studs
b. have no blocking between them

then it won't be hard at all to retrieve the end of the wire through the hole and you will have a nice, clean, safe run and not have to repair anything at all afterwards. Maybe you have a good reason not to do this, but I would think its your best bet.

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