My inspector was really cool about it did not require a second inspection he said he would check it on the insulation inspection. The wires went from 2nd floor to basement then across the basement through 5 - 1 3/4 holes about 75ft to the panel. It was alot to change the wires, it took 2 men about 4 hours to change it.
Amount of romex in hole
- Thread starter alcon192
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electricmanscott
Senior Member
- Location
- Boston, MA
- Occupation
- Massachusetts Master Electrician, one man show.
Did we actually conclude that there was a violation? 
jack horner
Banned
- Location
- America
dcspector said:
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 bundled together and pass through wood framing that is to be fire- or draft-stopped using thermal insulation or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).
Section 310.15(B)(2)(a) states in part: ``or where single conductors or multiconductor cables are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a).'' Failure to comply with the appropriate adjustment ampacity derating called for by this table, where nonmetallic-sheathed cables may be stacked or bundled, can lead to overheating of conductors. For the 2005 Code, a new derating requirement was added to prevent overheating of Type NM conductors where passing though draft- and fire-stopping material.
It doesn't say anything about holes in the top plate. Only where they are bundled or draft-and fire-stopping material is used. This can happen though at some top plates. So the answer is sometimes?
jack horner
Banned
- Location
- America
jack horner said:
I hate to quote my own post but..... when I read this I would agree that the cables also must be bundled for at least 24" and pass through a framing member that will be draft-or fire-stopped.
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
jack horner said:
The way that it's written I would agree. But if they're already bundled for more than 24" then derating would apply whether or not they went through a firestopped hole.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Exactly.... so why put this section in the code--- I believe it is because your interpretation is not what is meant by this section.infinity said:
Two wires together are bundled whether they are together for 24" or 6". The difference is if it is more than 24" then you have to derate. IMO, they are still in a bundle if they are stapled together for 6"-- you just don't have to derate. Now read the article with that in mind.
The NEC does not define bundled. The dictionary does... 1. several objects or a quantity of material gathered or bound together.
To give more creedence to my statement read art.310.15(B)(2)--adjustment factors ....where single conductors or multiwire cables are stacked or bundled longer than 24"without maintaining space.....
It dooes not say bundling is stacking for 24". I think you are trying to make art.334.80 suit your needs. Now I agree I believe it is a bunch of bunk but I cannot see how you can interpret it the way you are trying.
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I worked with a guy whom did not allow it and wrote a letter to our chief electrical inspector at the time asking the question. Once you write out the question it looks quite silly. It never got a official response. It read like this:
Question: 1) Does Article 310.15(B)(2)(a) require derating for runs of more than two NM cables containing two or more current-carrying conductors that are construed as "bundled" together. By bundling we mean pass through 1.5" wood framing every 16 inches in total lengths of run exceeding 24 inches that is not to be fire or draft stopped using thermal insulation or sealing foam.
Example: In a 1 family dwelling two 14/3 NM and two 12/3 NM runs typical "home" runs. Holes bored in 1.5" 2X8 run at angles to joists 16 inches on center like a typical set of "home runs". The cabels are not in very close contact in the 14.5 inches of free air between joists, but not far apart, lets say an average of 1/4 - 1/8 inch apart. All conductors are copper supplying non-linear and linear loads.
Question 2) Is it permissible to use the calculated load of a residential general purpose 120 volt branch circuit for derating as required by 334.80 or for derating required if answer is yes to above question 1.
Example above has 12 current-carrying conductors ( 4 cables 3 current-carrying conductors each).
Ambient temp will not exceed 30 deg C.
Calculate the load In a 1 family dwelling for the 14 AWG phase conductors in the NM cable.
The branch circuit is a 120 V general purpose type in a dwelling unit and will not serve more than 500 Sq FT of the dwelling. (220.14(J)) 500SQ FT X 3VA per SQ FT. = 1500VA. OR Alternatively We count the 8 outlets and multiply by 180VA or calculate the connected loads to be conservative and come out with <1500VA. This 12.5 AMPS load. 50% of 14 AWG NM as per table 310.15(B)(2)(a) 12 current-carrying conductors. T310.16 to size wire using the 90 deg C (as permitted in 334.80) 25A X 50% = 12.5Amps. Over current device is next size up as per 240.4(B) = 15 Amps.
Sample letter
I worked with a guy whom did not allow it and wrote a letter to our chief electrical inspector at the time asking the question. Once you write out the question it looks quite silly. It never got a official response. It read like this:
Question: 1) Does Article 310.15(B)(2)(a) require derating for runs of more than two NM cables containing two or more current-carrying conductors that are construed as "bundled" together. By bundling we mean pass through 1.5" wood framing every 16 inches in total lengths of run exceeding 24 inches that is not to be fire or draft stopped using thermal insulation or sealing foam.
Example: In a 1 family dwelling two 14/3 NM and two 12/3 NM runs typical "home" runs. Holes bored in 1.5" 2X8 run at angles to joists 16 inches on center like a typical set of "home runs". The cabels are not in very close contact in the 14.5 inches of free air between joists, but not far apart, lets say an average of 1/4 - 1/8 inch apart. All conductors are copper supplying non-linear and linear loads.
Question 2) Is it permissible to use the calculated load of a residential general purpose 120 volt branch circuit for derating as required by 334.80 or for derating required if answer is yes to above question 1.
Example above has 12 current-carrying conductors ( 4 cables 3 current-carrying conductors each).
Ambient temp will not exceed 30 deg C.
Calculate the load In a 1 family dwelling for the 14 AWG phase conductors in the NM cable.
The branch circuit is a 120 V general purpose type in a dwelling unit and will not serve more than 500 Sq FT of the dwelling. (220.14(J)) 500SQ FT X 3VA per SQ FT. = 1500VA. OR Alternatively We count the 8 outlets and multiply by 180VA or calculate the connected loads to be conservative and come out with <1500VA. This 12.5 AMPS load. 50% of 14 AWG NM as per table 310.15(B)(2)(a) 12 current-carrying conductors. T310.16 to size wire using the 90 deg C (as permitted in 334.80) 25A X 50% = 12.5Amps. Over current device is next size up as per 240.4(B) = 15 Amps.
you said it yourself "you just don't have to derate"Dennis Alwon said:
i believe if the intent was to derate ANY bundled conductor the "longer than 24" " would have been omitted
as it reads - "....are stacked or bundled longer than 24" without maintaining space...."
when you pass through a top plate the "bundle" is only 6"-12" long... therefore no derating is required...(as long as the conductors "seperate " on either side)
however- if bundled ANYWHERE longer that 24" (for any reason) then you have to derate...
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
mayjong said:
I do not argue this fact what I argue is when fire stop foam or thermal insulation is used to fill the holes. Article 334.80 second paragraph does not say that the wires must be bundled for 24" and pass through wood framing that is to be fire stop, etc. It simply says when two or more cables are bundled (this does not mean 24") and pass thru wood framing that is to be fire stopped or thermal insulated, then you must derate.
We all know we have to derate if bundled for more than 24". This is a different scenario that is requiring derating--- the fire stop situation is the difference.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
- Status