my inspector told me that they must not take up more than 50% of the capacity of the hole, or 4 wires max through ANY size hole.

he said 3 12-2 wires is pushing it for 3/4", but is still okay.

Mike,

If you're describing running cables through bored holes in framing, then arichard21 is probably describing a local code requirement. There is no "fill" limitation in the NEC that I know of. There are some requirements about bundling cables together, but that wouldn't apply unti you exceed 4 cables.

You have probably hit the practical limit. You might be able to fit a 4th cable in there, put I'd hate to pull it through more than a couple of holes.

Thanks for the advice, I'll stick to 3 cables. I couldn't imagine trying to pull a 4th one through, 3 was already a wrestling match. Thanks again

Just make sure the cables are not tightly together outside of the hole.
The AHJ could ping you for having them bundled.

If more than two NM cables pass through a hole that is to be fire or draft stopped, then you have to derate according to T310.15(B)(2)(a).

"If more than two NM cables pass through a hole that is to be fire or draft stopped, then you have to derate according to T310.15(B)(2)(a)."

What does this mean...is the top double 2X4 plate (not sure of correct term) that sits on top of the wall framing considered a fire or draft stop?

Now I am worried. I will take some pictures and post.

Here is a link that might be useful: Oh NO !!

Groundrod's post is alarmist. There is NO concern with anything less than five "cables".

Yes, two (2-wire) cables, or more accurately four conductors, require derating, but this is NOT an issue when we are talking about 9 conductors or less of size #10, #12 & #14.
We use the 90 deg C column for derating and nine or less uses a 70% derating. Even this 70% is no less than the typical ampacity for these size wires. This is due to 240.4(D).

IMO this type of thing is not even worth mentioning and only serves to confuse non-trade folks. Why bother saying two cables needs derating when the bottom line ampacity numbers DO NOT change.

Also, groundrod, can you tell us where you see ANY reference to fire or draft stopping with regard to derating. I see no such notations.
Cables simply passing through holes DO NOT require derating.

Well, I DO apologize. There was a paragraph added to 334.80 in the 2005 NEC with regard to two or more cables passing through fire stopping material.

My previous comment stands though about nine or less conductors. Two cables is of no concern as far as derating goes. Five 2-wire cables would need adjustment....IF your area follows the 2005 NEC.