Coax in Heating duct? - AVS Forum
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post #1 of 20 Old 10-29-2009, 12:12 PM - Thread Starter
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I'm probably going to be putting another Dish box In a room in my house. I really want to avoid drilling holes in the floor if I can help it. I'm going between 2 rooms on the same floor, the run will probably be around 50 feet I think. I have to go through the floor, into the basement and up again into the other room. I was thinking about running the cable in the heating duct? I don't know if this would be a problem though, I don't want to do something that's unsafe. I have a long run of outdoor coax that I got from a previous house and that's probably would I would be using.

Another thing I thought of was pulling the vent cover and trying to run the cable next to the duct and not actually in it, I have to see if there's room, but I'm really not sure this would really make all that much difference in heat.

Any suggestions? Thanks.
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post #2 of 20 Old 10-29-2009, 01:02 PM
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If your local jurisdiction uses an electrical code based on some version of the NEC, running cable in a duct is probably illegal.
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post #3 of 20 Old 10-29-2009, 01:04 PM
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Buy plenum-rated cable and you'll be fine.

Belden 9116P is an example of such a rated cable.
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post #4 of 20 Old 10-29-2009, 01:46 PM
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As mentioned you can run the coax in the ducts but for codes it needs to be plenum rated which is usually white although not all white coax is plenum rated.
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post #5 of 20 Old 10-29-2009, 02:09 PM - Thread Starter
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will it say on the cable
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post #6 of 20 Old 10-29-2009, 03:43 PM
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A plenum is not the same thing as a duct. You cannot run cable in a duct even if it is plenum rated and be code compliant.
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post #7 of 20 Old 10-29-2009, 04:09 PM
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Rating aside...

If want to run a coax, just take off the vent cover, drill a hole to the side of the vent and run outside of the duct work.
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post #8 of 20 Old 10-30-2009, 02:04 PM
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Quote:
Originally Posted by Colm View Post

A plenum is not the same thing as a duct. You cannot run cable in a duct even if it is plenum rated and be code compliant.

Correct. Never legal or okay in a duct, which is a "feed." A plenum is a return pathway and can even be over a suspended ceiling.
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post #9 of 20 Old 10-30-2009, 02:04 PM
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Quote:
Originally Posted by Ratman View Post

Rating aside...

If want to run a coax, just take off the vent cover, drill a hole to the side of the vent and run outside of the duct work.

Good answer.
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post #10 of 20 Old 10-30-2009, 02:15 PM
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Quote:
Originally Posted by IAMQNOW View Post

Correct. Never legal or okay in a duct, which is a "feed." A plenum is a return pathway and can even be over a suspended ceiling.

Is it code to run plenum cable in a ducted return?
I know it's OK above a plenum ceiling but what about a ducted return like in a house?
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post #11 of 20 Old 10-31-2009, 12:19 PM
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If it looks like a duct, walks like a duct, and quacks like a duct, it is a duct...
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post #12 of 20 Old 10-31-2009, 12:27 PM
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Quote:
Originally Posted by ProjectSHO89 View Post

Buy plenum-rated cable and you'll be fine.

Belden 9116P is an example of such a rated cable.

I agree. From a practical purpose, plenum rated cable in a duct achieves the goal of preventing toxic smoke in living spaces.
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post #13 of 20 Old 10-31-2009, 02:04 PM
 
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Quote:
Originally Posted by Colm View Post

A plenum is not the same thing as a duct. You cannot run cable in a duct even if it is plenum rated and be code compliant.

Please provide the appropriate NEC code for running low voltage cable in a heating/cooling duct.
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post #14 of 20 Old 10-31-2009, 03:24 PM
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820.3(b) and 300.22(b) govern. You cannot do what OP wants, just run the coax through the duct. You can only do it if you put the coax inside conduit in the duct.

If you don't believe me, maybe you will you believe Mike Holt?
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post #15 of 20 Old 10-31-2009, 03:43 PM
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It never ceases to irk me that someone "owns" these NEC laws that we must obey, that we can't see them unless we pay for a copy, and that we can't even print excerpts that are long enough to adequately address NEC compliance concerns that arise in the ordinary course of residential communications wiring installation.
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post #16 of 20 Old 10-31-2009, 03:59 PM
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Public libraries where I live have the NEC. But it is a pain. My state incorporates the NEC into the state code by reference, with modifications, then the county incorporates the state code into its code by reference, with modifications. At least the county makes its modifications available free on-line.

Even if you have the NEC, it is often a pain to figure out just what applies. The NEC Handbook, which is an annotated version of the NEC helps some. You need to have the skills of a lawyer sometimes.

Think the cost of the NEC is bad? Go look at what the AWS charges for welding codes, and there are many of them.
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post #17 of 20 Old 10-31-2009, 05:08 PM
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Unfortunately, the half a dozen public libraries I have found "the Model Code" in over the years all only had editions that were either one or two revisions behind the most current one. In fairness to those libraries, there is usually a lag of one to three years in adopting each new revision, so quite often, those "older" Model codes were, in fact, the current basis for the enacted codes in those jurisdictions.

BTW, for those working in commercial buildings, it is permissible to ground to a cold water pipe at a point more than 5 feet from where it enters the building, provided that plumbing is substantially exposed and professionally maintained.
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post #18 of 20 Old 10-31-2009, 05:13 PM
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Yes, many jurisdictions will be using an edition of the code earlier than the most recent one. Latest edition from NFPA is 2008. My state is using 2005.
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post #19 of 20 Old 10-31-2009, 05:46 PM
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Quote:


On the other hand, five fingers.

- Pat Paulsen

On the other hand, "professional" installers violate the NEC every day, sometimes even at the behest of their employers, who often decide based on what they are being paid for each installation and what the risk of chargebacks are.

I hardly ever do residential installations anymore, but I still would not be averse to grounding to any convenient water pipe. Sometimes, on commercial rooftops, I ground to the electrical conduit going to heat pumps. We all do. Back before DirecTV and DISH came along, there was little attention paid to grounding, and I can tell you from personal experience that less than ten percent of the hundreds of antennas I have serviced on highrise buildings in the Washington, DC, Northern Virginia/Suburban Maryland area installed prior to the mid-1990s were grounded to code.

I personally would not be averse to running a coax in an air duct in my own home, but wouldn't do it for a customer.

In existing, single family homes, electrical codes are enforced by the mattress tag police. I would never run low voltage communications wiring in the same conduit as line voltage wiring, but I'll do just about anything else if conforming with the NEC is too costly. But then, when I worked for the state highway department thirty-six years ago, installing guardrail posts, they gave our crew a chainsaw, and if we hit rock digging our hole with a foot or two to go, "Bzzzzz...".
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post #20 of 20 Old 10-31-2009, 05:53 PM
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Quote:
Originally Posted by AntAltMike View Post

It never ceases to irk me that someone "owns" these NEC laws that we must obey, that we can't see them unless we pay for a copy, and that we can't even print excerpts that are long enough to adequately address NEC compliance concerns that arise in the ordinary course of residential communications wiring installation.

Here. Try this. It's a little dated, but it does have links to the 2005 and 2008 NEC.
bulk.resource.org/codes.gov/
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