romex cable routing

[tom31415926]

I understand that unprotected Romex cable may not be run across the tops of ceiling joists (perpendiculat to the joists), unless the headroom above the joists is less than some value (I've been told 18 inches).

I would like to run some romex perpendicular to joists in the center of my attic, where there is plenty of headroom. I could build a wiring channel that attaches to the joist tops, and install the cable in it. Where can I find the specifications for an acceptable wiring channel?

I was thinking of making an L-shaped channel from 1 x 4 wood (or smaller?). The bottom of the L would be nailed to the joist tops, leaving the side to stick up and offer some protection. The romex would be stapled to the top of the wood that forms the bottom of the L.

If I want to run many cables, must I staple all of them independently, or would some other means of holding them in the channel be allowed? I cojld build a full U-shaped channel and have periodic bridges across the top to hold the cables in.

Is there a better or easier way to do this?

thanks

Tom

[HayZee518]

wiring running perpendicular to the joist need a running board nailed atop the joist run. it doesn't have to be sophisticated as an L shaped board, just a board. a channel with wires installed in it would have to be derated because there is no free air to dissipate heat. wires just stapled to the running board would have free air around them. by rights you should staple individual cables to the running board, but you may be able to double up on the cables if the staple is deep enough. Ideal Co makes a nail on bracket out of plastic that accepts stacked conductors with free air around them so derating isn't necessary. Usually it's used on vertical studs in a wallspace going to switch boxes or outlets.

[tom31415926]

thanks, HayZee!

I'll use a board wide enough to keep free air around the wires.

Tom