Romex stuff

[leftcoastsparky]

Used to be you could use common sense in running romex through 2x4 studs and plates. (ex. 4-14/2 through a 1-1/4" hole.) Now, around here it is 2 wires, no exceptions. I know thats not set in stone and there are exceptions. What are they? TY

 

[augie47]

I would say the "2" is a case of misunderstanding of the NEC.
The "rule" from 334.80 is:
Where more than two NM cables containing two or more current-carrying conductors are installed in contact with thermal insulation without maintaining spacing between cables, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).

 

[leftcoastsparky]

Thanks Augie, now what constitutes "mantained spacing and in your opinion would, say 4-14-2 home runes in a inch and a quarter hole be permissable? how about 1 ko in a TJ?

 

[al hildenbrand]

Thanks Augie, now what constitutes "mantained spacing and in your opinion would, say 4-14-2 home runes in a inch and a quarter hole be permissable?

You'll have to nailplate the stud faces with less than 1-1/4" of wood to the edge of the 1-1/4" hole. I never use more than a 3/4" bit in 2x4s.

 

[tom baker]

The local myth here is three cables. I have asked why and none one knows. It may be 3 is all you can get through a 3/4" hole. Or back when we had NM with 60 deg C insulation.
Even with 3 cables and NM-B thats not an issue as the derating is based on 90 deg c

 

[chris kennedy]

now what constitutes "mantained spacing

One atom, one free electron, the NEC doesn't specify.

 

[Dennis Alwon]

In reality the code states you must derate when more then 2 cables are run thru a hole. However, since nm is rated 90C for derating purpose you can use 30 amps for #12 wire. 8 current carry conductor-- four 2 wire cables-- would derate 70%. 30 amps at 70% still leaves us with 21 amps. Thus we can be compliant with 4- 12/2 nm cables when bundled or thru a caulked hole.

 

[iwire]

However, since nm is rated 90C for derating purpose you can use 30 amps for #12 wire. 8 current carry conductor-- four 2 wire cables-- would derate 70%. 30 amps at 70% still leaves us with 21 amps. Thus we can be compliant with 4- 12/2 nm cables when bundled or thru a caulked hole.

I agree with Dennis.

 

[ActionDave]

I agree with your agreeing with Dennis and also agree with Dennis and Tom.

I disagree with the bundling rule. When did this become an issue?

 

[leftcoastsparky]

As to when did it become an issue.............in the central coast and bay area it never was a few years back. It was common place to see a 2" hole in the upper plate (nail plated) and all the home runs comming through. I chose to do it a bit different and ran my subfeed in the middle and home runs to the outter holes. But I would often have 3 wires in a whole and no more than 2 at the subpanel connector. Same goes for the plate above a 4 or 5 gang box. Often times you would see 3 or 4 14's through a hole. No more. Thanks to all for the input. You fellas are great!

 

[renosteinke]

When did it become an issue? The moment some 'home inspectors' bought code books and suddenly became experts. It was their agitating that led to the code being changed.

Ditto for the 'no Romex in damp locations' rule being extended so as to apply to virtually all crawl spaces. No matter that the IAEI has down-played the issue; any sign of moisture in the crawlspace, and you can't run your Romex down there.

Silly? You bet - but the sooner you realize that unqualified HI's, and other well-meaning folks, are hijacking the trade, the better our chances are of stopping them.

 

[480sparky]

When did it become an issue? The moment some 'home inspectors' bought code books and suddenly became experts..........

HI's actually buy NECs? Thanks for the laugh..... I needed that. :roll:

NECs are way out of the price range for HIs. They're more likely to buy Code Check : Electrical.

 

[renosteinke]

Yea, I appreciate the humor, too!

Still, it is in our own interest to monitor the various HI sites, just to see the 'unique perspective' of the posters. Heaven alone knows what code silliness they will next attempt.

Judging by what I have seen, HI forums are sorely lacking in folks with any real electrical knowledge.

 

[jimport]

Yea, I appreciate the humor, too!

Still, it is in our own interest to monitor the various HI sites, just to see the 'unique perspective' of the posters. Heaven alone knows what code silliness they will next attempt.

Judging by what I have seen, HI forums are sorely lacking in folks with any real electrical knowledge.

Ouch!

 

[tryinghard]

So derating doesn't apply when the hole is not going to be insulated?

 

[Dennis Alwon]

So derating doesn't apply when the hole is not going to be insulated?

That is correct. Now if you had a bunch of wires running horizontally thru the studs for more then 2' then an inspector may call that bundling.

 

[tryinghard]

That sure makes sense :roll:?

 

[iwire]

When did it become an issue? The moment some 'home inspectors' bought code books and suddenly became experts. It was their agitating that led to the code being changed.

Ditto for the 'no Romex in damp locations' rule being extended so as to apply to virtually all crawl spaces. No matter that the IAEI has down-played the issue; any sign of moisture in the crawlspace, and you can't run your Romex down there.

Silly? You bet - but the sooner you realize that unqualified HI's, and other well-meaning folks, are hijacking the trade, the better our chances are of stopping them.

Please show some real evidence of HIs changing the NEC.