NEC Wiring Methods & Raceways — Flashcards

NEC Chapter 3 (Articles 300–393) governs wiring methods and raceways, specifying materials, installation practices, and protective measures for electrical conductors. Common raceways include EMT, rigid conduit, and PVC, while wiring methods encompass cable types (NM, AC, MC). Key requirements emphasize proper support, grounding, and separation of circuits. 

Key NEC Wiring Methods & Raceways (Chapter 3)

Raceways (Enclosed Channels):
EMT (Electrical Metallic Tubing - Art. 358): Lightweight, common in commercial/industrial.
RMC (Rigid Metal Conduit - Art. 344): Heavy-duty protection, often threaded.
PVC (Rigid Polyvinyl Chloride Conduit - Art. 352): Corrosion-resistant, used underground or in damp locations.
ENT (Electrical Nonmetallic Tubing - Art. 362): Flexible, corrugated plastic, known as "smurf tube".
FMC (Flexible Metal Conduit - Art. 348): Used for flexibility in connecting equipment.

Cable Assemblies:
Type NM-B (Nonmetallic-Sheathed Cable - Art. 334): Commonly used for residential branch circuits (dry locations).
Type AC/MC (Armored/Metal-Clad Cable - Art. 320/330): Used for commercial, industrial, and some residential, providing, durable armor protection.
 

General Installation Rules (Article 300):
Protection: Conductors must be protected from physical damage.
Support: Cables and raceways must be secured at specific intervals.
Fill Limits: Raceways cannot be overcrowded to avoid overheating (Article 300).
Separation: Power conductors are often separated from low-voltage systems. 

Important Distinctions:
Cables vs. Conductors: Cables (e.g., NM) are assemblies, whereas raceways typically hold single insulated conductors (e.g., THHN).
Prohibition: Generally, NM cable cannot be installed inside a complete conduit system, though it can be used for short sleeves.
Panelboard Use: A panelboard cannot be used as a raceway for conductors feeding through unless specifically designed for that purpose.