The 120-volt circuit supplying power to a fire alarm system must be dedicated. This means it must be on a separate branch circuit serving no other loads.

The 120-volt circuit supplying power to a fire alarm system must be dedicated. This means it must be on a separate branch circuit serving no other loads.

• A. It must be on a separate branch circuit serving no other loads
• B. It may share with lighting circuits
• C. It may be on a multi-wire branch circuit
• D. It must be on a circuit with GFCI protection

Answer: (A)

The essential idea is that the power for a fire alarm system must come from a circuit that serves only that system. Keeping the 120-volt feed on a dedicated branch circuit ensures the alarm has a reliable, predictable supply and isn’t affected by other loads turning on, off, or drawing heavy current. If the circuit also fed lights or outlets, a nuisance trip, voltage drop, or overload could interrupt the alarm’s power when it’s most critical, which could delay or impair notifications. Sharing with lighting would introduce potential instability and trips that could disable the fire alarm. A multi-wire branch circuit would complicate protection and could create a shared fault condition that jeopardizes continuous operation. GFCI protection isn’t the controlling factor here; fire alarm feeders are treated as dedicated power sources to prioritize reliability, so the main point is isolation from other loads.

The essential idea is that the power for a fire alarm system must come from a circuit that serves only that system. Keeping the 120-volt feed on a dedicated branch circuit ensures the alarm has a reliable, predictable supply and isn’t affected by other loads turning on, off, or drawing heavy current. If the circuit also fed lights or outlets, a nuisance trip, voltage drop, or overload could interrupt the alarm’s power when it’s most critical, which could delay or impair notifications.

Sharing with lighting would introduce potential instability and trips that could disable the fire alarm. A multi-wire branch circuit would complicate protection and could create a shared fault condition that jeopardizes continuous operation. GFCI protection isn’t the controlling factor here; fire alarm feeders are treated as dedicated power sources to prioritize reliability, so the main point is isolation from other loads.