Wiring Methods: NM Cable, Raceways, and Securing Rules

"Rough wiring" is the phase where the wiring methods go in before the walls close. Each method has its own NEC article, its own permitted uses, and its own securing and support spacing — a favorite exam topic.

1. Type NM cable ("Romex") — Article 334

NM (nonmetallic-sheathed) cable is the workhorse of dry, indoor residential wiring.

• Secure within 12 inches of every box, cabinet, or fitting, and support every 4.5 feet. (CEC 334.30)
• Uses permitted (334.10): dry, protected interior locations — dwellings and light commercial.
• Uses NOT permitted (334.12): wet or damp locations, exposed to physical damage without protection, embedded in concrete, hazardous (classified) locations, and as service-entrance cable.
• Where exposed NM could be subject to physical damage, protect it — e.g., with RMC, IMC, EMT, or Schedule 80 PVC. (334.15(B))