1) can I run 1 12/3 romex cables through a 1/2" hole in studs.

2) can i run 2 12/2 romex cables in the same 3/4" hole in studs

Let's start with where you live and which code you must follow. Are you asking if the diameter of the romex will fit the size hole or if it is legal to run romex through studs. Not all romex is the same diameter but it should easily fit.

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Originally Posted by ballengerb1

Let's start with where you live and which code you must follow. Are you asking if the diameter of the romex will fit the size hole or if it is legal to run romex through studs. Not all romex is the same diameter but it should easily fit.

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I live in suffolk county New York and the wires do fit but I would like to no if it is legal

It's easier with the larger holes but yes, you can run it that way.

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Originally Posted by ma0641

It's easier with the larger holes but yes, you can run it that way.

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Thank you

No more that two cables in one hole. More that two will get you into derating of wiring, and no need to go there.

This is one of the rare times I'll disagree with TK.

Typically, with #14, #12 & #10 wire, you can run up to four cables in a bored hole.
For those size wires you do not have to worry about derating until you get to nine CCC's (current carrying conductors). This includes the neutral. This does not however include the neutral of a multi-wire home run (3-wire cable).

So basically you can have up to four 12/3 home runs in a single hole before derating has any effect.

There is another stipulation where if the holes are to be firestopped you have to make provisions for two or more cables. My examples above were for general framing.

I got pinched for more than two years ago, dumb as a rock back then, being lazy now and just threw that out there.

Did a ton of residential work, back in the day. I try to be careful answering resi questions off the top of my head.

So I went and checked myself. Stan, I am going on Table 310.15(B)(2)(a), 4-6 gets derated 80%, and since NM cable, I am assuming is used, uses the 60 Deg C column, derating begins there. Maybe that's where I am wrong?

Newer NM cable uses THHN conductors inside the cable, so derating begins with the 90 deg C column, which is the actual ampacity of the conductor.

The 60 deg C limitations and 240.4(D) are after the fact.

Stan,

To the best of my knowledge, even though the newer NMB cables use THHN conductors, they are not identified as THHN on the conductors and are therefore limited to the 60 "C" table.

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Originally Posted by donf

Stan,

To the best of my knowledge, even though the newer NMB cables use THHN conductors, they are not identified as THHN on the conductors and are therefore limited to the 60 "C" table.

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This is not true at all. They are not labeled individually, which is why you cannot strip them out and use them, but they ARE identified as 90 deg THHN so that is what you base derating on.

Scroll down for the construction specs: http://www.southwire.com/ProductCata...dcatsheetOEM10

This mouse does not want to be on the dance floor when elephants decide to Tango, but could someone tell me what this means

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dry locations at temperatures not to exceed
90°C (with ampacity limited to that for 60°C conductors) as specified in the National
Electrical Code

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