Metal Floor Joists and Wiring

[braken1996]

I am building a house and have installed Metal Floor Joists instead of wood. What is the code for wiring the lights in the basement? I know that I have to use plastic grommets, but do I also have to use Romex or metal boxes? Any help would be great.

 

[caj1962]

Re: Metal Floor Joists and Wiring

I am not familar with metal floor joists but as far as metal studs yes you can use nm cable and metal boxes. If you try to use the plastic nail on boxes it bends the nails. ha ha

 

[aecjohn]

Re: Metal Floor Joists and Wiring

yes you can use RX provided that you use grommets. You can tek screw recessed lights in. They do make front "screw" on plastic boxes but I dont think they are ceiling rated/

 

[a.wayne3@verizon.net]

Re: Metal Floor Joists and Wiring

aecjohn why wouldn`t they be acceptable as long as there is an 8/32 screw to mount the fixture,and the support was adequate.If on a wall a single gang box is acceptable but on a ceiling just use slider boxes and tex screws.wood or metal no difference just the grommets and the stand offs.

 

[stew]

Re: Metal Floor Joists and Wiring

Just my 2c worht but I woulod us mc cable and metal boxes.

 

[aecjohn]

Re: Metal Floor Joists and Wiring

oopps, I meant plastic single gang front screw on. I dont recall seeing the 'c' rating inside the box.

 

[msd]

Re: Metal Floor Joists and Wiring

Consider this.

What is your method of support / and strap 12" from the box, and is it listed or approved for the application (used to secure RX).

STEW - I'm with you.

I woulod us mc cable and metal boxes

For support I would use tie-wire or a 1 hole 3/8" strap. Then, I would pass inspection.

Also, your States' Administrative Code may not allow RX in metal framed construction. Check with the local AHJ to be sure. MC cable would be a much simpler solve.

 

[shocker3218]

Re: Metal Floor Joists and Wiring

A bracketed 4 square box and a round p-ring would supply enough support for almost any fixture (You need to use more support for ceiling fan installs) RX be strapped by driving a staple through the stud and cinching it on the back side (or into a scrap of wood) Our state does not recognize mc or bx of any kind as an approved wiring method. But I have been allowed to use 3 #12 wires in a short piece of 3/8 flex (figure that one out?)

 

[msd]

Re: Metal Floor Joists and Wiring

If you can figure out how to use a staple "driven into wood" then you should be good to go.

BTW - what backwards state allows RX but not MC