Electrical – Bending radius for NM cable through stud

Jay, I think you can use NM for this application as long as you do not cross beam. Cross beam refers to bridging between collar ties or floor joists across the bottom of said members, as opposed to drilling mid member and lacing the cable through the holes or following parameter beams and extending inward for each fixture along sides of 2X4's

My first choice would be BX or greenfield plastic coated flex raceway. EMT would be great, but maybe a little impracticable for your application.

While your local code amendments may differ, the following codes are recognized in the National Electrical Code 2014

1. Conductors entering boxes need to be closed and protected with approved means.

   314.17 Conductors Entering Boxes, Conduit Bodies, or Fittings Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion and shall comply with 314.17( A) through (D). (A) Openings to Be Closed. Openings through which conductors enter shall be closed in an approved manner.

2. An exception is allowed when NM wire is used BUT ONLY when a single gang box is used not larger than 2 ¼ in. × 4 in. and mounted on walls or ceilings and the cable is fastened within 8".

   314.17 (C) Exception: Where nonmetallic-sheathed cable or multiconductor Type UF cable is used with single gang boxes not larger than a nominal size 57 mm × 100 mm (2 ¼ in. × 4 in.) mounted in walls or ceilings, and where the cable is fastened within 200 mm (8 in.) of the box measured along the sheath and where the sheath extends through a cable knockout not less than 6 mm (¼ in.), securing the cable to the box shall not be required. Multiple cable entries shall be permitted in a single cable knockout opening.

3. NM wire installed on A WALL of unfinished basements requires proper protection with conduit or similar tubing AND the conduit shall be provided with a insulated bushing or adapter at the point of entry.

   334.15 (C) In Unfinished Basements and Crawl Spaces. Nonmetallic-sheathed cable installed on the wall of an unfinished basement shall be permitted to be installed in a listed conduit or tubing or shall be protected in accordance with 300.4. Conduit or tubing shall be provided with a suitable insulating bushing or adapter at the point the cable enters the raceway. The sheath of the nonmetallic-sheathed cable shall extend through the conduit or tubing and into the outlet or device box not less than 6 mm (¼ in.). The cable shall be secured within 300 mm (12 in.) of the point where the cable enters the conduit or tubing. Metal conduit, tubing, and metal outlet boxes shall be connected to an equipment grounding conductor complying with the provisions of 250.86 and 250.148.

4. Conductors entering building need protection.

   300.5 (D) (2) Conductors Entering Buildings. Conductors entering a building shall be protected to the point of entrance.