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Someone tried telling me today that you can only run 2 12/2 pieces of Romex through a 3/4" hole drilled through a stud. I said there's no such code. At least I never heard of such a thing but he swears by it. Is there anything that limits the amount of cables through a hole?
 

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334.80 Ampacity. The ampacity of Types NM, NMC, and
NMS cable shall be determined in accordance with 310.15.
The allowable ampacity shall not exceed that of a 60°C
(140°F) rated conductor. The 90°C (194°F) rating shall be
permitted to be used for ampacity adjustment and correction
calculations, provided the final derated ampacity does not ex-ceed that of 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 392.80(A).
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 sealed with thermal
insulation, caulk, or sealing foam,
the allowable ampacity
of each conductor shall be adjusted in accordance with
Table 310.15(B)(3)(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 be-tween cables, the allowable ampacity of each conductor
shall be adjusted in accordance with Table 310.15(B)(3)(a)

Pete
 

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334.80 Ampacity. The ampacity of Types NM, NMC, and
NMS cable shall be determined in accordance with 310.15.
The allowable ampacity shall not exceed that of a 60°C
(140°F) rated conductor. The 90°C (194°F) rating shall be
permitted to be used for ampacity adjustment and correction
calculations, provided the final derated ampacity does not ex-ceed that of 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 392.80(A).
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 sealed with thermal
insulation, caulk, or sealing foam,
the allowable ampacity
of each conductor shall be adjusted in accordance with
Table 310.15(B)(3)(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 be-tween cables, the allowable ampacity of each conductor
shall be adjusted in accordance with Table 310.15(B)(3)(a)

Pete
I (somewhat) stand corrected :). Thanks Pete.

Still at 80% you're allowed 4-6 CCC's, so that would be 3, 12-2 Romex cables.

Really, in a 3/4" hole, without stuffing it full, I doubt you could get many more than 3 anyway.
 

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I (somewhat) stand corrected :). Thanks Pete.

Still at 80% you're allowed 4-6 CCC's, so that would be 3, 12-2 Romex cables.

Really, in a 3/4" hole, without stuffing it full, I doubt you could get many more than 3 anyway.
You can run 4- 12/2's or 4- 14/2's. By derating the #12 would be at 30 amp in the 90 deg column. 8 ccc @ 70% would be 21 amps so you are good. Same with #14 8 ccc @70 of 25 amps would be 17.5 on a 15 amp ocd.
 

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You can run 4- 12/2's or 4- 14/2's. By derating the #12 would be at 30 amp in the 90 deg column. 8 ccc @ 70% would be 21 amps so you are good. Same with #14 8 ccc @70 of 25 amps would be 17.5 on a 15 amp ocd.
I thought you were required to use the 60 deg column for nm?
 

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I thought you were required to use the 60 deg column for nm?
You are. Read the entire code article Pete posted. You can use the 90 deg. column for derating but the ampacities of the wire must not be below the rating in the 60 deg. column. So with derating for 8 ccc #12 wire has an ampacity of 21 amp. So it is above the max ocp of 20 amps. Same with # 14. 17.5 ampacity of the wire on a 15 amp breaker.
 
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