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Is it safe to run cables through air ducts?

yoda313 posted 2008 Jun 22 14:19

Ok here's the situation - I want to run a phone cable from one floor to another. I don't want to cut anything nor do any kind of line fishing. Can I use duct work to snake a phone cable around? I don't have a phone jack in the room I intend to move my dsl modem to. I know they have wireless adapters to turn power outlets into phone jacks but I don't want to spend close to a 100.00 on this project. So is this safe? Also how could I get it out of the vent cover? How do you crimp a phone jack plug onto a phone cable? Ideas are welcome. FYI this is so I can use my router and dsl modem in the same room with my ps3 and xbox 360 for media sharing off my vista pc.

edDV posted 2008 Jun 22 15:10

Probably against code and rental agreements. If this is your house, you can fish telco wire through walls under the floor or via ceiling. It all depends on your house construction. When I was in an apt, I fished telco wire under carpets to convert a dining room into an office. That was probably against code as well.

Nelson37 posted 2008 Jun 22 15:17

I know there is a different type of Ethernet cable to be used in plenums, though I don't know exactly why this is. The dude that taught me how to run cable 15 years or so ago indicated it was something to avoid. Maybe something with the temperature changes? To crimp a phone jack onto phone cable, you use (wait for it) - a phone jack crimping tool. Very cheap. Many Ethernet RJ45 crimpers will also handle phone (RJ11).

ron spencer posted 2008 Jun 22 16:56

what do you mean air ducts? there are two type: 1. heating 2. cold air heating I avoid "just in case" cold air has no downside...just cold air.

gll99 posted 2008 Jun 22 17:49

I don't know about building codes so can't advise you on that but IMO this is a low risk solution. This is low voltage communication equipment not electrical wiring so it shouldn't cause a problem. Years ago I ran a wired intercom which only ran on a 9 volts dc battery after I modded it from our 3rd floor bedroom to my basement office/workshop. I went though a heating duct at a point about 10 - 15 feet from the furnace. At the time I would have preferred to use the cold air return but upstairs it was in the middle of a hallway on an opposite wall. All I did is remove the cover from the heating duct upstairs and fished and wiggled a fairly stiff but flexible multi filament steel wire into the pipe until by my estimate it had reached the basement. With a friend upstairs to wiggle the wire I went down to listen for movement in the basement pipe. I pried the duct joint on the bottom, found the steel wire, pulled it through and then duct taped the phone cable to the steel wire end to end to form a smooth line making sure the unplugged phone extension cable was long enough not to get fished back into the pipe. I went back up and pulled it through. To pass it through the cover I just pried the centre of the fins with a wide flat screw driver just enough to get the head of the connector through the back of the cover but not enough to actually cause a visible bend. I put the cover back on the hole and pulled as much phone line as needed. Downstairs I had to leave a small slit / bend where the duct pipe joins to let the phone line through and used metal tape to reseal the pipe joint and cover the small slit / bend for the phone wire. This worked great for many years until I moved but the removal was even easier. I just cut the line downstairs at the duct pipe and pulled it back up through the bedroom vent and that was it.

yoda313 posted 2008 Jun 22 18:18

Yeah I have no idea about code so I'd probably not end up doing this. Its just kinda one of those "what if" ideas that popped in. What exactly is "plenum"? Is that some kind of heavy duty plastic casing? I'm sure I'll figure out something. Thanks for the advice.

jagabo posted 2008 Jun 22 18:35

A plenum is the air space between a false ceiling and the real ceiling, between the walls, etc. Plenum cable has thicker solid core copper wire and thicker plastic shielding that doesn't give off toxic fumes when burned. It's less flexible than patch cable (what you use within a room) but can withstand more stress during installation (like when being pulled through conduit).

gadgetguy posted 2008 Jun 22 21:21

According to fire/electrical code, it is never ok to run wire in air ducts. Plenum rated cables can be run in plenum spaces as described by jagabo, but not in ducts. In case of fire, both hot and cold air ducts are paths for the fire to spread if there is anything in them that can act as a fuel source. Wire (even plenum rated wire), dust, spiderwebs, trash, and almost anything else that falls through the register can be a fuel source. It's recommended that your air ducts be cleaned at least once a year. Edit: I was discussing this with a friend and he said that if you have wire in your ducts and have a fire, the insurance company can deny, or partially deny the claim. Wire in the ducts can be considered a willful violation and a contributor to the covered loss. He couldn't site an example of this actually happening and he's not an insurance man, so I don't know if this is fact or speculation, but I thought I'd pass it along.

yoda313 posted 2008 Jun 28 09:51

Thanks everyone. I think I may have gotten my ethernet switch to work in place of my dsl modem/wireless router configuration. I still have to tweak it though. I will pull up a previous post for further discussion on it. Hopefully this thread may prove useful for other people.

yoda313 posted 2008 Aug 08 19:36

Bump - well I struck on something the other day. I have a whole for my CABLE!!! DUH! I'm just gonna drill it a little wider. Turns out the darn thing is only big enough for the cable itself. It is so narrow that even adding the flat phone cable is too much extra thickness for both to fit. This will be great. I'll be able to snake the phone cord through the cable hole and I'll be able to have a live net connection with my dsl modem and wifi router in the same room with the 360 and ps3. Thanks everyone.

johns0 posted 2008 Aug 08 19:59

I put a phone wire thru a heating vent cover 17 years ago,just replaced it cause the clip broke off that secures it to the phone.

yoda313 posted 2008 Aug 08 20:05

I've heard they have tools to recrimp those connector points. I've never seen one but it would have prevented the need of rerigging the phone cord..... Though I'm sure it was cheaper to replace the cable then to buy a new tool :D :D

gadgetguy posted 2008 Aug 08 21:54

The crimp tool is about $6US at Home Depot. I think it comes with a half dozen connectors.

yoda313 posted 2008 Aug 09 08:44

gadgetguy : The crimp tool is about $6US at Home Depot. I think it comes with a half dozen connectors. Wow that cheap huh? Didn't know.

usually_quiet posted 2008 Aug 09 09:10

I think mine (purchased there last year) was a little more than that, about $10. Still reasonable though, and not difficult to use. It saved me the trouble of replacing the whole cord.

redwudz posted 2008 Aug 09 10:19

When they wired my new home for phone lines, they used eight conductor CAT5e cable, all brought back to a central junction box. Since I just use a cell phone, I converted the wall connectors to a Ethernet configuration for my LAN. They can be converted back to a phone configuration if necessary in the future. I also added a Ethernet switch for distribution to the junction box and fed one line back to the box from my router. :D I suppose you could use the other four unused Ethernet wires in the cable (Or usually just two are needed) to run phone signals on the same CAT5 concurrently, though that could cause interference to either system. Phone wires carry just a few volts except for the ringing signal, which can be up to 90V during ringing, but all low current. I found out about the 90V once when I was holding the wires and someone rang my phone number. :lol: In a pinch and not recommended as they aren't usually twisted pairs, you could use a regular phone line for a Ethernet line on a very short run. There are just 4 active wires in most Ethernet cables. Or if the phone wires are loose enough in the walls, tie a Ethernet cable to the end and pull it through in place of the phone cable. CAT5 will work fine for phone or Ethernet, just the connections are different at the ends. BTW, I would agree it's not a good idea to run any cables through air ducts, for all of the stated reasons, and one more. The cables would likely rattle against the sides of the metal ducts whenever there was air movement and the noise would drive you crazy. :lol:

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