wire strapping

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wiredup

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hi i have a question for you guys, i got called by an inspector for strapping home runs with romex shealth, ive been doin this for a while with companies that thought me to do that. inspector is saying i cant strap more than 3 wires in the attic. i know about not taping them due to the heat factor but i never heard of not being able to wrap all my home runs going the same direction with romex shealth, which i staple to the boards. can anyone let me know if he is right? i dont know where the code for this is. this is in california. thanks in advance
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I've seen pictures of this, but I've never done it. I always nail or screw a piece of 2x4 flat, between the studs and flush with the backside of them. That places the stapling surface 2" behind the front face of the studs.
 

wiredup

Member
im talking about doing this sort of thing through out the whole attic space, where the home runs go, nailing boards, and using staples will take too much time. and it looks so much neater wapping them with romex shealth and stapling it
 

infinity

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Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Sounds as if he's concerned with derating the now bundled conductors. Once you get past 9 CCC's bundled together for #14,and #12 cables you will end up with a lower ampacity than the typical 15 amps for #14 or 20 amps for #12.
 

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
You already have a heat issue in the attic and bundling the wires together just makes for more heat and possible issues down the road.

Trevor got it right-- you must derate if you have more than 4-- 2 wire cables together for more than 2'. Table 310.15(B)(2)
 

guschash

Senior Member
Location
Ohio
I don't think it's in the code. Article 334.30 ......similar fittings designed... I have seen this done but never done because I never in a hurry but I don't see why you can't. I wouldn't bundled more than 4 or 5. How many are you you bunling?
 

dnem

Senior Member
Location
Ohio
wiredup said:
hi i have a question for you guys, i got called by an inspector for strapping home runs with romex shealth, ive been doin this for a while with companies that thought me to do that. inspector is saying i cant strap more than 3 wires in the attic. i know about not taping them due to the heat factor but i never heard of not being able to wrap all my home runs going the same direction with romex shealth, which i staple to the boards. can anyone let me know if he is right? i dont know where the code for this is. this is in california. thanks in advance

"wrap all my home runs going the same direction with romex shealth"
I can't picture this. . Are you taking an empty piece of cast-off sheath and wrapping it in a spiral around several HRs ? . And are you doing this to protect the HRs from staple damage ?
 

wiredup

Member
not too concerned about the staple damage, its just that i have probobly lets say 15 or so homeruns heading the same direction and instead of stapling them i just wrapit a couple times around all off them and staple it to the board. this is a normal sized residential track home im talking about, i never had inspectors call this sort of thing, untill now. ive seen it donein alot of homes.
 

dnem

Senior Member
Location
Ohio
You've said he told you to limit it to 3 Romexs but that doesn't seem to jive with 310.15(B)(2)(a). . If your bundled areas are longer than 24" you would have to keep your count to one single Romex. . If your bundled areas are not "maintaining spacing" [however you want to interprete that] you would have to keep your count to one single Romex.

Where does the 3 come from ? . 3 is the number of current carrying conductors that have no T310.15(B)(2)(a) adjustment factor. . It's not the number of Romexs. . Plus you don't get adjusted down under 20a until you hit 80% ampacity for 10 CCCs. . 334.80 para 2 limits you to 2 Romexs when dealing with fire stopping penetrations. . I don't see a 3 limit anywhere.

David
 

Davis9

Senior Member
Location
MA,NH
I think if you start at the 90 deg column and derate from there on RX then you will see where the 9CCC limit comes from.

Tom
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
wiredup said:
im talking about doing this sort of thing through out the whole attic space, where the home runs go, nailing boards, and using staples will take too much time. and it looks so much neater wapping them with romex shealth and stapling it
not too concerned about the staple damage, its just that i have probobly lets say 15 or so homeruns heading the same direction and instead of stapling them i just wrapit a couple times around all off them and staple it to the board.
This definitely exceeds bundling limits. I'd recommend a few cable stackers side-by-side every third framing member (or whichever spacing maintains the maximum of 4.5').
 

wiredup

Member
homeruns

homeruns

how do you guys run homeruns? just want to get some ideas, most of the homes i do are track homes, so i have to have the quickest way of wiring these homes so i wont be losing money.
 

wiredup

Member
LarryFine said:
This definitely exceeds bundling limits. I'd recommend a few cable stackers side-by-side every third framing member (or whichever spacing maintains the maximum of 4.5').

thats not a bad idea larry, if that what i have to do i will start to do that. any faster methods?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
wiredup said:
thats not a bad idea larry, if that what i have to do i will start to do that. any faster methods?
In my opinion, there is nothing faster. Hammer in a single 8-penny nail and slide the wires in.
 

wiredup

Member
how much of a voltage drop would i be losing if they were all together? maybe for like 30 to 40 feet. strapped together?
 

augie47

Moderator
Staff member
Location
Tennessee
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State Electrical Inspector (Retired)
strapped together

strapped together

it's not so much a question of voltage drop as it is heat..bundling can result in excessive heat and damaged insulation.

I see folks using Larry's idea very often..seem sto work fine and is apparently a labor saver
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
wiredup said:
how much of a voltage drop would i be losing if they were all together? maybe for like 30 to 40 feet. strapped together?
Voltage drop is not the issue with bundling. It's the inability to disipate the heat that all conductors develop while carrying current.

To compensate for this, it is necessary to either use a smaller OCPD or a larger conductor.

If you wish to use a given conductor size, you must do the former; if you have a required ampacity, you must do the latter.
 

dnem

Senior Member
Location
Ohio
LarryFine said:
post #11

wiredup said:
post #3
im talking about doing this sort of thing through out the whole attic space, where the home runs go, nailing boards, and using staples will take too much time. and it looks so much neater wapping them with romex shealth and stapling it

wiredup said:
post #8
not too concerned about the staple damage, its just that i have probobly lets say 15 or so homeruns heading the same direction and instead of stapling them i just wrapit a couple times around all off them and staple it to the board.

This definitely exceeds bundling limits. I'd recommend a few cable stackers side-by-side every third framing member (or whichever spacing maintains the maximum of 4.5').

Are you saying ?definitely exceeds bundling limits? because ?15 or so? together is not ?maintaining spacing? [310.15(B)(2)(a)] ? . Because I don?t picture this as being a violation of exceeding the 24? long bundle limit. . His bundled areas are probably not longer than 6?.

David
 

dnem

Senior Member
Location
Ohio
I don't see heat dissipation as an issue in the bundle itself if the bundle is 24" or shorter. . The "maintaining spacing" concept could be a problem with 15 HRs in constant contact for their entire length thru the attic. . But you have to define "maintaining spacing". . If you choose the wording of 392.11(A)(3) then if you have more than one layer or have less than one cable width of space between any 2 cables, you are not "maintaining spacing".

You would then have to derate according to T310.15(B)(2)(a) and limit your 14 & 12 gauge Romexs to bundles of *4* Romexs if you didn't want to reduce your breaker size.

I'm still not seeing the limit of 3.

Here's the math:
*4* 2wire Romexs are 8 current carrying conductors.
*4* 3wire Romexs are still just 8 current carrying conductors because you don't count the noodles [310.15(B)(4)].
8 CCCs have a 70% adjustment factor [T310.15(B)(2)(a)]. . The starting point for 12gauge is 30a [T310.16 & 334.80]. . 30a x 70% is 21a. . Since you're still above 15a [240.6(A)], you can still use the 20a breaker [240.4(B)] the same as without adjustment [240.4(D)].

*5* 2wire Romexs are 10 current carrying conductors.
10 CCCs have a 50% adjustment factor [T310.15(B)(2)(a)]. . Again starting point for 12gauge is 30a [T310.16 & 334.80]. . 30a x 50% is 15a. . Since you're at 15a, you have to use that breaker instead of the usual 20a.

If there’s a fire stopping bundling issue, at first glance you might think you’re limited to *2* Romexs based on how the second paragraph starts. . But 334.80 ends with the words “the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a)” which brings you right back to the math.

If there’s a bundling issue, you’re limited to *4*.
Where’s the limit of *3* come from ?

David
 
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LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
dnem said:
His bundled areas are probably not longer than 6?.
I don't believe that bundling only refers to the length where the cables are actualy secured together, but the entire length from the first wrap to the last, unless you provide some mechanical method of spacing the cables between wraps.

According to your way of thinking, a group of cables run through a single row of bored holes in framing would not be bundled because they're only held together for 1.5" every 16". In my opinion, they're bundled from the first hole to the last hole.

The only true bundling of cables to you would be where they share a conduit.
 
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