Which cable type is appropriate for a non-power-limited circuit?

• A. Nplf
• B. Nmb
• C. THHN
• D. NM

Answer: (A)

In fire alarm wiring, circuits are split into power-limited and non-power-limited categories, and the cable chosen must match that category. For a non-power-limited circuit, the appropriate cable is Non-Power-Limited Fire Alarm Cable, designated to meet the specific insulation, flame-retardant, and signaling requirements of non-power-limited fire alarm circuits. This ensures the circuit remains reliable and compliant under fire code provisions.

The other cables are used in different contexts: NMB is a general-purpose nonmetallic-sheathed cable for typical building wiring; THHN refers to individual conductors used in conduit rather than a jacketed fire alarm cable; NM is standard residential cable not rated for fire alarm signaling circuits. None of these meet the non-power-limited fire alarm cable designation, so they aren’t appropriate for that type of circuit.