Bundling Romex

[finster1]

The days of drilling a hole down the center of the basement and branching out your conductors is over...I guess, although I see it all over. They want the romex to have an air gap.....What are you guys doing these days to the service panel where all this spaghetti comes together and space is at a premium. Even following the perimeter of the basement is a no no but what are the alternatives you guys are using? Interested in hearing everyones input. I personally am using alot more stacker clamps to make it happen but I go on jobs and it doesn't seem like everyone is concerned with doing it correctly...Are inspectors still allowiong big bundles of romex to fly?

 

[jmsbrush]

Finster what code section are you talking about as far as doing it right?

 

[chris kennedy]

We are still under the 05 here.

 

[infinity]

Bundling is very subjective so inspectors might not see a problem where multiple cables pass through a hole every 16" but have air around them in between the framing members.

 

[wbalsam1]

The days of drilling a hole down the center of the basement and branching out your conductors is over...I guess, although I see it all over. They want the romex to have an air gap.....What are you guys doing these days to the service panel where all this spaghetti comes together and space is at a premium. Even following the perimeter of the basement is a no no but what are the alternatives you guys are using? Interested in hearing everyones input. I personally am using alot more stacker clamps to make it happen but I go on jobs and it doesn't seem like everyone is concerned with doing it correctly...Are inspectors still allowiong big bundles of romex to fly?

Take a look at Article 300 Wiring Methods and 310.15(B)(2)

 

[finster1]

code section 300-4-(d)

 

[frizbeedog]

We are still under the 05 here.

Shhh. Keep it down, I have a headache.

 

[ohm]

Finster1, I believe this is one of the hardest rules in the code to enforce. Just what constitutes "an air gap"? 1", 1/2", 1 micron?

I wonder how many homes have burned down due to this problem?

If you're dropping 24 pieces of romex into a 16" cavity to the SE panel w/ the 08 code you need 12 holes... 1.33" c-c. So, you'll pass the electrical but fail the mechanical.

 

[steelersman]

We are still under the 05 here.

LOL!! That's funny as hell!

 

[infinity]

I wonder how many homes have burned down due to this problem?

My guess is none.

If you're dropping 24 pieces of romex into a 16" cavity to the SE panel w/ the 08 code you need 12 holes... 1.33" c-c. So, you'll pass the electrical but fail the mechanical.

Why would you need 12 holes? For #14, #12 and #10 condcutors derating won't really affect ampacity until you exceed 9 CCC's. That means you could get up to (4) 2 or 3 wire cables per hole with no change in cable ampacity.

 

[Brady Electric]

Bunding Romax

Bunding Romax

I just don't fill holes too tight giving room for air
Coming down at the panel I usually nail a couple of 2x4's across the studs and staple romax neatly two or three on top of each other if I don't have room for just one. Look neat when done
Just a stupid question, Why does it take so long for others states to catch up on the new code? Looks like everyone would keep up on the code. When the code comes into effect here say in January we get until April or May to start using the new code which I think is good. I like keeping up to date with the new codes.
Allot of electricians grip about it and I have in the past but when you stop and think about it enforcing the new code makes you more money.
Semper Fi Buddy

 

[wbalsam1]

Quote:
Originally Posted by ohm
If you're dropping 24 pieces of romex into a 16" cavity to the SE panel w/ the 08 code you need 12 holes... 1.33" c-c. So, you'll pass the electrical but fail the mechanical.

My guess is none.
Why would you need 12 holes? For #14, #12 and #10 condcutors derating won't really affect ampacity until you exceed 9 CCC's. That means you could get up to (4) 2 or 3 wire cables per hole with no change in cable ampacity.

Could he be referring to 334-80 for fire-and draft-stopping? This rule makes a huge difference in the amount of conductors (NM cables) per hole from floor to floor.

 

[Dennis Alwon]

Quote:
Originally Posted by ohm
If you're dropping 24 pieces of romex into a 16" cavity to the SE panel w/ the 08 code you need 12 holes... 1.33" c-c. So, you'll pass the electrical but fail the mechanical.




Could he be referring to 334-80 for fire-and draft-stopping? This rule makes a huge difference in the amount of conductors (NM cables) per hole from floor to floor.

I am sure that is what he is saying but derating will not affect the nm cable until there are more than 4 nm cables in a hole as Trevor pointed out. Ohm is saying you can only have two / hole.

 

[wbalsam1]

I am sure that is what he is saying but derating will not affect the nm cable until there are more than 4 nm cables in a hole as Trevor pointed out. Ohm is saying you can only have two / hole.

More than 3 current-carrying conductors, not cables. :smile:

 

[Dennis Alwon]

More than 3 current-carrying conductors, not cables. :smile:

......................

Where more than two NM cables containing two or more current-carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be fire- or draft-stopped using thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.
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).

 

[Dennis Alwon]

More than 3 current-carrying conductors, not cables. :smile:

So if you have 4 nm cables that is 8 ccc. * cc is derated 70%. 70% of 30 amps for #12 wire is 21 amps. It does not affect the situation until 5 cables or 9 cc conductors are involved.

 

[wbalsam1]

Quote:
Originally Posted by wbalsam1
More than 3 current-carrying conductors, not cables. :smile:

So if you have 4 nm cables that is 8 ccc. * cc is derated 70%. 70% of 30 amps for #12 wire is 21 amps. It does not affect the situation until 5 cables or 9 cc conductors are involved.

I was actually referring to the adjustment factors in 310.15(B)(2) and mixed them up with 334.80. You're right, of course, there is a difference in the number of conductors/cable permitted.
As far as your text I've highlighted above, you're assuming a correction factor of 1.00 in an ambient temperature of 78-86.

 

[ohm]

......................

Dennis, the last paragraph goes even further "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).

So, if you have a bunch of wire converging on an SE panel and they are parallel for 24" or more they must all be derated by a factor of 80 to 35% depending on the number of current carrying conductors, unless you "maintain adequate spacing" between them.

Art 100 does not define thermal insulation or spacing so is 1", 1/2", etc. OK between cables burried in insulation? And, do you derate all of the cluster (including the range, dryer & sub panel feeders?

With the advent of 1" AFCI breakers, panels are no longer limited to 42 spaces. I forsee a drastic reduction of MWBC and 1/2" breakers, and mush more clutter at the SE panel.

 

[mark32]

We are still under the 05 here.

I agree with steelersman, that was dam funny Mr. Kennedy

 

[ohm]

My guess is none.




Why would you need 12 holes? For #14, #12 and #10 condcutors derating won't really affect ampacity until you exceed 9 CCC's. That means you could get up to (4) 2 or 3 wire cables per hole with no change in cable ampacity.

True, if you ty-wrap four 12-2 NM together it's about 0.65" O.D. and four 12-3's are about 0.75" so they may fit OK in a 1" hole. The number of cables in a 14.375" space could be as high as the number I threw out ..or less. But, IMO you better drill a bunch of them before you start pulling wire thru them or you may tear them up with your ship auger.

And, as you stated in an earlier quote..bundling is quite subjective. So much so that it was dropped from Art. 100 in 08.

An irate EI or ME can have a hayday with wire around an SE panel.