The maximum overcurrent protection device for a power-limited fire alarm system shall not exceed how many amps?

The maximum overcurrent protection device for a power-limited fire alarm system shall not exceed how many amps?

• A. 10
• B. 15
• C. 20
• D. 30

Answer: (C)

Power-limited fire alarm circuits are designed so fault currents stay small and the wiring and devices stay protected. Because of this protection philosophy, the overcurrent protection device (the fuse or breaker) for these circuits must not be rated higher than 20 amps. Keeping it at 20 amps ensures that, in a fault, the device interrupts quickly enough to prevent damage and maintains the intended safety of the power-limited design. Using a smaller rating would cause nuisance trips during normal operation, while a larger rating would allow fault currents that exceed the safe limits for these circuits. So, the maximum is twenty amps.

Power-limited fire alarm circuits are designed so fault currents stay small and the wiring and devices stay protected. Because of this protection philosophy, the overcurrent protection device (the fuse or breaker) for these circuits must not be rated higher than 20 amps. Keeping it at 20 amps ensures that, in a fault, the device interrupts quickly enough to prevent damage and maintains the intended safety of the power-limited design. Using a smaller rating would cause nuisance trips during normal operation, while a larger rating would allow fault currents that exceed the safe limits for these circuits. So, the maximum is twenty amps.