Holes in studs to run romex

[Brian Loran]

Can I drill more than one hole in a wall stud to run electrical wire through? Also, is there a max diameter hole I can drill? I am adding some wiring in my garage/shop and this is an out side facing wall if that matters.

[Steve Meliza]

An outside wall is a load bearing wall so yes, there are strict limits. I don't have them in front of me at the moment (I think it is 40% of the stud width), but if you put a 1/2" to 3/4" hole centered in the stud and another several inches above or below it then you should be fine (use the smallest hole that you can). If you don't center the hole and the wire is less than 1.25" from the edge of the stud then you need to use a nail plate. You also don't want to drill these holes to close to the ends of the studs, stay back several inches.

[Jason Roehl]

A 1/2" hole is, IMHO, too small for 12-2(w/ground) Romex. I've done it, it's not fun to pull the Romex through.

[Josiah Bartlett]

Check your local building codes, they address this.

[Paul Merrill]

I use a 7/8" or 1" auger bit, if you center the hole, it leaves you with about a 1-1/4" of wood. This gives you plenty of room to run two or three wires through the hole. Depending on what guage wire you are running.

[Brian Loran]

That must be why an existing run of wire is going through a small hole (must be 1/2"). No way I can squeeze another wire through that same hole so I need to drill a new one somewhere else. Sounds like I should go higher (current one is only ~1ft off the ground) and could possibly go to 3/4", 7/8" or 1" (I will check building codes) so I can run multiple romex through. I need to get 1 110V and 2 220V sockets down that way. Thanks for the help everyone.

[Steve Meliza]

While you are checking building code you might ask the electrical inspector if there are any issues running three NM cables through the same hole in the wall. It may not be an issue at all, but I know you're not supposed to bunch up NM cables so that they can dissipate heat.

[Ron Natalie]

While the local electrical code may vary, the NEC doesn't care how many cables you pass through a bored hole. Those aren't considered bundled up (as long as they spread out once they escape from the hole).

[Jim Andrew]

If you use a 1" hole, and 3 wires, less chance of hitting a wire than with several holes and wires spread out. Talking about hanging cabinets and such. Might think about a certain height that you could remember so you don't run screws in at that height. I have a studfinder with electrical wire detector, but the thing gives a range about 18" wide, when checking for wires. And there is only one wire in the wall I was checking.

[Dan Hintz]

I'd prefer to have a number of wires going through one hole protected by a metal plate than multiple unprotected holes (and no one wants to put up multiple metal plates as there's nothing to screw into at that point).

[Brian Loran]

Good points about the multiple holes. Still trying to find a local code inspector contact... but sounds like there shouldn't be any problem running 3 wires through a 1" hole a decent distance from the existing smaller 1/2" hole. What gauge do you guys recommend? I am thinking 10/2 for the 220Vs and 12/3 for the 110 GFCIs.

[Dan Hintz]

I am thinking 10/2 for the 220Vs and 12/3 for the 110 GFCIs.

Only reason to run 12/3 is if you plan on switched paths somewhere down the line (and then you run 12/3 just from the point you need it)... I'd just put in 12/2 for the GFCIs.

[Steve Meliza]

Wire size is determined based on current and not voltage. In general, use #12 for 20A and #10 for 30A. And like Dan said, 12/2 is fine for a single 110V outlet, not sure what you would use the fourth wire for in 12/3 in your case.

[Jerome Stanek]

12/3 if you want 2 circuits.

[Jerome Hanby]

12/3 if you want 2 circuits.

Just to give you a double hit of Jeromes, I've wired all mine with 12/3 to make it easy to convert from a single 240 to a double 120.