Section 316.310. Conductors for general wiring.

  This is a department rule in addition to the requirements in NEC 310.15 (B) (3) (a): The derating factors shown in NEC Table 310.15 (B) (3) (a) do not apply to branch circuits supplying an individual dwelling unit except under the following conditions:

Exception No. 6: The derating factors shown in NEC Table 310.15 (B) (3) (a) do not apply to branch circuits supplying an individual dwelling unit except under the following conditions:

(1)  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) (3) (a) and the provisions of 310.15 (A) (2) shall not apply.

(2)  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) (3) (a).

CR 08-047 : cr. Register February 2009 No. 638 , eff. 3-1-09; CR 13-042 : am. (title), (intro.) Register November 2013 No. 695 , eff. 12-1-13; corrections in (intro.), (1), (2) under s. 13.92 (4) (b) 7. Register November 2013 No. 695 .