Electrical Wiring Rough-in Techniques
I’ve got to run some armored wiring for some shop lights in a garage. I have questions regarding drilling through studs/rafters for the conduits. I’m not really crazy about the idea of drilling a 1-1/2-inch hole in the roof rafters to run the conduits. I could drill the studs, but I’d have to drill a million of them to get to the light locations.
What are the rules for drilling roof joists and beams for electrical conduits?
And what size flexible conduit do I use for 12 or 14-gauge?
The most direct path for the lights is through 4 or 5 roof rafters and then through a large beam (8 by 12).
Replies
Unless your local code requires armored cable, I would not use it. Local codes in my area forbid it's use except for up to three feet to attach to a fixture. I don't know why they forbid it. I think it has something to do with inductive heat build up.
Unless you are attaching sheet rock directly to the rafters, I would staple Romex wire or clamp EMT to the surface of the rafters.
1/2" conduit is plenty big enough for most 14 and 12 awg lighting circuits depending how many wires and how many 90 degree bends in each. You should not need to be drilling any 1-1/2" holes for lighting circuits.
Local codes require armored cable. The drywall is being attached directly to the rafters (not much headroom).
I'm using the garage as a workshop space and am adding a television, in-wall stereo speakers, flush mounted light fixtures, nice cabinets. Although just a garage, I really don't want exposed EMT, especially since right now all the studs/rafters are exposed.
Sounds like I should just go all around and drill studs, then go on the side of the rafters.
Purchase a roll of MC cable for your wire runs. It meets code requirementsfor "armor cable" and is small enough in diameter to need no larger than a 3/4" hole bored in any structural members. It is a prewired armor flex, available with two or three conductors and ground. NEC gives the support spacing needed for MC cable and other amored cables.
Dave
Those holes are a lot of work, and they weaken the structure. Since this is a garage, why not go with exposed EMT? -- Even if it's over sheetrock.
-- J.S.
Even easier just run Romex above the joist. Nail down a running board and attach it to the running board.
For armored cable you might not even need the running board, but I would have to look that up.