How many power supplies must a residential fire alarm system have?

The correct answer indicates that a residential fire alarm system must have two power supplies to ensure reliability and safety. This dual power supply requirement is essential for maintaining the operational integrity of fire alarm systems, particularly in the event of a primary power failure.

One power supply typically comes from the building's electrical system, while the second serves as a backup, commonly derived from a battery or an alternative source. This redundancy is crucial because fire alarms are critical life safety devices, and any failure to operate due to a lack of power could have severe consequences. The second power supply guarantees that the alarm can still function even during a power outage, ensuring ongoing monitoring and alerting capabilities in the event of a fire.

In some jurisdictions or specific applications, the code set forth by the National Fire Protection Association (NFPA) or local regulations may specify the necessity of dual power sources for residential fire alarm systems to comply with safety standards. This guideline underscores the importance of being prepared for unforeseen circumstances that could otherwise inhibit the alarm system's performance in an emergency.