NM-B and THHN are examples of what category of wiring used in electrical installations?

• A. They are examples of wiring methods and conductors used in electrical installations
• B. They are types of circuit breakers
• C. They are insulation colors
• D. They are grounding electrodes

Answer: (A)

Wiring methods and conductors used in electrical installations. NM-B is nonmetallic-sheathed cable (the common Romex used in homes), which bundles insulated conductors with a grounding conductor inside a protective sheath. THHN is a type of insulated conductor used in conduit systems, with insulation rated for different temperatures and environments. Both represent the actual wiring components and how they’re installed, rather than protective devices, color codes, or grounding electrodes. So they’re examples of wiring methods and conductors, not circuit breakers, insulation colors, or grounding electrodes.