How many NM through punch outs

[Wiliki]

The house has Insulated Concrete Form walls and a surface mount panel seems to be in order. Due to the number of homeruns, it seems we don't have enough punch-out holes. We're thinking of using a pull box next to the panel and then putting say 2-3 NM cable through short nipples into the panel.

Given the short distance of conduit, is there a way to justify not having to derate the conductor ampacity. (If we ran 3 cables we'd have to derate to 80%, if we ran 4 cables we'd have to derate to 70%)

 

[Sparky9527]

I think the nipple has to be 24" or less. Then you don't have to derate. But the fill has to be less than 60% of the conduit.

 

[Dennis Alwon]

Most nm cable connectors are rated for 2 cables.

Another option is this


C) Cables.

312.5(C) Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.

Exception No. 1:
Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met:

• (1)
  Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway.
• (2)
  The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
• (3)
  A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation.
• (4)
  The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway.
• (5)
  The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 6 mm (1⁄4 in.).
• (6)
  The raceway is fastened at its outer end and at other points in accordance with the applicable article.
• (7)
  Where installed as conduit or tubing, the cable fill does not exceed the amount that would be permitted for complete conduit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto. Note 2 to the tables in Chapter 9 does not apply to this condition.