Journeyman Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A fire alarm control panel (FACP) is being installed in a new commercial building. The 24V DC fire alarm circuits are routed within the building. What is the minimum required rating for the conductors used for these fire alarm circuits, as specified by NEC Article 760?
- A90°C (194°F)
- B105°C (221°F)
- C75°C (167°F)
- D60°C (140°F)
Show answer & explanationAnswer & explanation
Correct answer: C. 75°C (167°F)
NEC Section 760.49 states that power-limited fire alarm (PLFA) circuit conductors shall have a minimum insulation temperature rating of 75°C (167°F). This ensures reliability and safety under normal operating conditions and potential fault scenarios.
Why the other options are wrong
- A. While 90°C conductors are often used, 75°C is the minimum rating required by the NEC for PLFA circuits.
- B. This rating is higher than the minimum requirement and while acceptable, is not the specified minimum.
- D. 60°C is generally too low for fire alarm circuit conductor insulation ratings.
Fire Alarm Conductor Temp Rating
The minimum insulation temperature rating required by the NEC for power-limited fire alarm (PLFA) circuit conductors to ensure their operational integrity.
- Applies to Power-Limited Fire Alarm (PLFA) circuits (NEC 760).
- Ensures conductor performance during operation.
- Minimum 75°C (167°F) insulation rating.
Memory trick: Seventy-five degrees, for fire alarm wires, that's what the NEC requires.