Bundling Of Nmc

Status
Not open for further replies.

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
sminor said:
Is There A Code Section That Prohibits Running Of 7-#14 Romex Thru A 3/4" Bored Hole In Framing?:)

Take a look at 334.80 of 2008 or 2005

I would also bet that 7 14/2 cables in a 3/4" hole would be very difficult to achieve.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
sminor said:
Is There A Code Section That Prohibits Running Of 7-#14 Romex Thru A 3/4" Bored Hole In Framing?:)


Short answer is no, this is permitted. There may be some issues with it however.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
infinity said:
Short answer is no, this is permitted. There may be some issues with it however.

What's the long answer. Certainly if they fit it can be done thru a stud if it isn't firecaulked. No???

MY long answer is if the wires are penetrating a floor that needs firecaulk then you must derate nm cable. Four 14/2 cables have 8 CCC. At 70%, based on Table 310.15(B)(2)(a), and Table 310.15 we can calculate the answer.

#14 is rated 25 amps and at 70% it would be rated 17.5 thus a 15 amp breaker is still good. Go amy higher and you are in trouble.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
sminor said:
So It Is Permitted And You Only Derate If It Is A Fire Rated Wall?

Any wall that has fire caulk will have to use the derating. Please tell us what you are doing and why this issue arose.
 
We Have Always Allowed Two Romex Per Hole Max, As We Do For Romex Clamps( Per Manuf. Listing For Clamps). I Have A Jobsite Where They Want To Run 7 14-2 Thru A 3/4" Hole. It Just Seems Like A Bad Install To Me, Too Much Heat Build-up. Almost Like Conduit Fill Limit. Is That Just Too Much Concern On My Part?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Dennis Alwon said:
What's the long answer. Certainly if they fit it can be done thru a stud if it isn't firecaulked. No???

MY long answer is if the wires are penetrating a floor that needs firecaulk then you must derate nm cable. Four 14/2 cables have 8 CCC. At 70%, based on Table 310.15(B)(2)(a), and Table 310.15 we can calculate the answer.

#14 is rated 25 amps and at 70% it would be rated 17.5 thus a 15 amp breaker is still good. Go amy higher and you are in trouble.


Long answer is I disagree with your derating calculation. The OP says "7-#14 romex" which is IMO 7-#14/2 cables which is 14 CCC's. Now your derating is 50% which brings you below 15 amps.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
infinity said:
Long answer is I disagree with your derating calculation. The OP says "7-#14 romex" which is IMO 7-#14/2 cables which is 14 CCC's. Now your derating is 50% which brings you below 15 amps.

Read my response Trevor. I was stating that 4 cables was the max. allowed thru a fire caulked hole. I realized the op was talking about 7 cables-- that won't fly but if it isn't ffirecaulk and a bunch of other if's, it could fly.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Dennis Alwon said:
Read my response Trevor. I was stating that 4 cables was the max. allowed thru a fire caulked hole. I realized the op was talking about 7 cables-- that won't fly but if it isn't fireball and a bunch of other ifs, it could fly.

Got it, no fire caulk and you're good to go. That's what I meant when I said my short answer is no this is not prohibited.
 
sminor said:
We Have Always Allowed Two Romex Per Hole Max, As We Do For Romex Clamps( Per Manuf. Listing For Clamps). I Have A Jobsite Where They Want To Run 7 14-2 Thru A 3/4" Hole. It Just Seems Like A Bad Install To Me, Too Much Heat Build-up. Almost Like Conduit Fill Limit. Is That Just Too Much Concern On My Part?

Assuming this is not a fire caulked hole.

7-14/2 NM cables through a bored hole is not going to lead to a heating issue. The issue may be a physical one. I have not measured or calculated the sizes, but pulling the 7 cables through that hole could damage the cables.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
chevyx92 said:
All I have available at the moment is the 2002. It must be different from the 05 + 08 because I don't see where it says what you are saying.

It was new in 05.

Here is the 08 with some revisions

334.80 Ampacity.
The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60?C (140?F) conductor temperature rating. The 90?C (194?F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60?C (140?F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
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).
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
chevyx92 said:
All I have available at the moment is the 2002. It must be different from the 05 + 08 because I don't see where it says what you are saying.


That requirement was added in the 2005 NEC.
 

splinetto

Senior Member
Location
Missouri
sminor said:
Is There A Code Section That Prohibits Running Of 7-#14 Romex Thru A 3/4" Bored Hole In Framing?:)
Did he say 7 wires?....Im feeling a little light headed...I'm going to have to sit down and raise my feet up...
 

kornbln

Senior Member
My house was built in 1968, all wired with NM and from what I've seen it all comes into the panel in a single hole through the top of the framing. No derating going on that I know of... When did bundling become an issue?
 
Status
Not open for further replies.
Top