I am drilling holes through a 2x6 ceiling joist. How many 12/2 wires can you run through a 7/8" hole? I am drilling the hole in the center of the 2x6 (width wise). Where is the best to drill the hole length wise?

Thank you for your help.

Imagine the length of the joist, and divide into thirds. Do not drill any holes in the center third. Only drill holes in the outer thirds. This not mean to make swiss chesse of the outer thirds.

Need to use some common sense to not drill so many holes the integrity and stength of the framing member is not comprimised.

The most you can fit in one 7/8" hole comfortably is two 12-2 cables. Any more will probably not physically fit without damaging the sheathing, and any more would require derating of the cables .

Damiging wires is not the issue here. There is a code to adhere to concerning how many wires through a hole and that code says 2. It has nothing to do with the size of the hole. TK should have mentioned that.

OK Sparky,

Did you happen to realize that this post was from five years ago!

Please back up your claim with the correct code citation.

Code does not say only two wires can be put through that hole.
The code is referring to cable, not individual wires. And within that context the size of the cable would make a difference, but I'm sure you already know that.

Damiging wires is not the issue here. There is a code to adhere to concerning how many wires through a hole and that code says 2.Can you tell me what code this is you are referring to?

I can tell you for a FACT that you have have up to nine current carrying conductors, sizes #14-#10 in a conduit, raceway or bundled cables, before derating is even a consideration. This means you can have up to four 12/2 cables in bored holes.

IMO three 12/2 in a 7/8" hole should be no problem.

Damn! I fell for the newbie digging up old threads again. :mad: