I am planning to wire my new condo for Ethernet, but unfortunately I don't have the usual basement/attic access that homeowners enjoy. Barring that, the easiest way to route cables where I need them to go is through the air ducts, terminating a few centimeters inside the duct, where the cable goes into the wall and down to a socket.

However, I've been getting conflicting information about whether or not this is permitted under the building code. In Canada (specifically Quebec) is it permitted to run plenum-rated Ethernet cable through ventilation ducts? I've seen conflicting answers online as to whether this is permitted or if the only wires permitted inside ducts are those related to the ventilation system. I can't access the building code myself without paying several hundred dollars for the privilege.

Barring that, can anyone recommend a good guide to running network cable through finished walls? All of the how-to guides I've seen crow about how easy it is but assume that you can go in through an unfinished basement or attic. Unfortunately, not only do I not have that luxury, the floors and most of the ceilings are concrete.

  • How is the existing building wiring in the floor and ceiling done? Commented May 10, 2017 at 23:57
  • @ThreePhaseEel A section of the ceiling about 2m wide and running the length of the open concept is lower and covered with drywall. The ventilation ducts and I assume most of the wires run through here, and it has several recessed light fixtures. I'm not sure exactly what is going on in there, if there are conduits that the wires run through.
    – Mikkel
    Commented May 11, 2017 at 5:13

1 Answer 1


In Ontario, Rogers spent years running their coaxial cables through duct work. The only downside was that the heat caused the wires to wear more quickly. I don't have access to codes here, but if Rogers did it then it's probably allowed.

Ethernet cables aren't shielded as well and would suffer the heat more. Maybe run them through the cold air return?

As an alternative, if you can get he cable to the right floor, stapling them to or behind baseboards worked well for me.

Hope that helps a little.

  • I'm surprised that code allows in-duct low voltage wiring.
    – Paulb
    Commented May 11, 2017 at 12:13
  • Thanks for the response. The condo has baseboard heaters; this duct is just for ventilation, so heat shouldn't be a concern. There is only one floor, but due to the layout, there's no continuous line of baseboards from the utility room to the rest of the condo.
    – Mikkel
    Commented May 11, 2017 at 12:52
  • Be sure to protect the cable where it enters/exits the duct. I have also used de-commisioned gargage chutes for cat cables.
    – John Canon
    Commented Jan 29, 2019 at 2:32

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