Wiring

[Ultraglide]

I need to run some wiring from my attic to the basement. Is it ok to run it down the cold air return?

[Ultraglide]

Thanks

[Jeff Wisnia]

You'll get no sensible answers until you tell us what the wiring is for, voltage(s) on it, and whether the wire type you are using is rated for duct applications. (ie plenum cable.)

Local codes may say you can't even do it no matter what cable type you use.

Jeff

[RBM]

Yes, provided it's type MI, MC, or steal tubing or metal conduit. Can't use Romex or BX

[gfretwell]

Not inside the duct but you can fish it down the chase next to the duct.

[Doug Miller]

No.

[The Daring Dufas]

From whom should he steal the tubing or metal conduit?

TDD

[ransley]

It may never pass code but may be safe if done with proper wire, but what if you snag a screw.

[RBM]

I think you're correct, and I can't say that I've ever run any kind of wiring through an air duct, but when I read 300.22, it's pretty difficult to make that distinction

[Boden]

If you run the wire in EMT and place the EMT inside the duct is the wire considered to be within the duct? I have several places where wires, some #4 AWG pass through return air ducts. They run in schedule 40 PVC through the duct.

Boden

[RBM]

You definitely can't run PVC or any plastic wiring or conduit through an air duct. I see your point regarding EMT or any metal conduit, but I believe it's still illegal unless it's affecting something within the duct. It would sure help if the NEC used clear wording though.

[gfretwell]

The only wiring that can be inside ductwork is wiring going to equipment inside the duct. Then the requirements on the wiring method apply.

[Ed Pawlowski]

No, he said cold air return. In my last house, it was a lined opening from the rooms to the basement, not a duct. Just a hole at the bottom end.

[David Nebenzahl]

On 10/28/2008 1:39 PM Ultraglide spake thus:

You mean *inside* the duct? You're joking, right?

[gfretwell]

That is even a more clear situation 300.22(C) exception says where stud space is used as an air return the wiring can only cross perpendicular to the studs, not along the long axis.

Exception: This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces.