If a fire alarm system does not use an uninterruptible power supply (UPS) for primary power, how many independent and reliable power supplies shall be provided?

If a fire alarm system does not use an uninterruptible power supply (UPS) for primary power, how many independent and reliable power supplies shall be provided?

• A. 0
• B. 1
• C. 2
• D. 3

Answer: (C)

Redundancy in primary power sources is required when a UPS isn’t used to back up the fire alarm’s main power. If the system doesn’t rely on a UPS for the primary power, it must have two independent and reliable primary power supplies so that the loss or disruption of one source doesn’t stop the system. Each supply should come from a separate source or path (for example different utility feeders or different service panels) to avoid a single point of failure. With two independent sources, the alarm remains powered even if one source fails, meeting the reliability requirement. That’s why the correct number is two.

Redundancy in primary power sources is required when a UPS isn’t used to back up the fire alarm’s main power. If the system doesn’t rely on a UPS for the primary power, it must have two independent and reliable primary power supplies so that the loss or disruption of one source doesn’t stop the system. Each supply should come from a separate source or path (for example different utility feeders or different service panels) to avoid a single point of failure. With two independent sources, the alarm remains powered even if one source fails, meeting the reliability requirement. That’s why the correct number is two.