Large commercial fire alarm systems often require more notification appliance power than the main panel can provide. When a building’s horn strobes, speaker strobes, and other notification devices draw more current than the control panel’s built-in NAC circuits can supply, a fire alarm booster power supply fills the gap. Understanding when supplemental power is required — and how to select, install, and troubleshoot booster power supplies — is essential knowledge for any fire alarm technician working on mid-size to large commercial systems.
Why Booster Power Supplies Are Required
NFPA 72 (National Fire Alarm and Signaling Code) requires that fire alarm systems have sufficient power to operate all devices under both normal and alarm conditions. Specifically, the system must be capable of operating in alarm for a minimum of 5 minutes following a 24-hour standby period (or 60 hours for certain occupancies) — all on battery backup.
Notification appliance circuits (NACs) are the primary power draw during alarm. Each horn strobe, speaker strobe, or chime draws current, and in large buildings with hundreds of appliances, total NAC current can easily exceed 4-10 amps or more. Most fire alarm control panels provide NAC outputs of 2-4 amps per circuit. When the total notification appliance load exceeds panel capacity, a booster power supply is required to provide additional supervised, battery-backed power for the NAC circuits.
Edwards BPS10A: Specifications and Features
The Edwards EST Remote Booster Power Supply BPS10A is one of the most widely used supplemental power supplies in commercial fire alarm applications. Key specifications include:
- Output capacity: Up to 10 amps at 24 VDC for notification appliance circuits.
- NAC circuits: Four individually supervised Class B NAC outputs, configurable as Class A.
- Battery backup: Supports sealed lead-acid batteries (sized per NFPA 72 standby requirements).
- Strobe synchronization: Built-in sync protocol support for compatible strobe devices.
- Supervision: Full supervision of AC power, battery, and NAC circuits with trouble reporting back to the main panel.
- Panel interface: Connects to the host panel via a supervised input circuit — the BPS10A reports trouble conditions to the main FACP.
The BPS10A is designed to work with Edwards EST panels including the EST3, EST2, and Fireshield series, but can also be used with non-Edwards panels when wired conventionally.
Compatible Panels and Applications
The BPS10A is most commonly deployed in large commercial buildings, healthcare facilities, and multi-building campuses where the EST3 or similar large-capacity panels are installed. Typical applications include:
- Large-floor hospitals and medical centers with hundreds of notification appliances per floor.
- University buildings and dormitories with voice evacuation speaker strobes on multiple circuits.
- High-rise office buildings where NAC wiring runs exceed panel loop current capacity.
- Multi-building campus networks where remote buildings require local power rather than long cable runs from the main panel.
For SIGA-series detector installations on the same EST system, pairing the BPS10A with properly listed Edwards SIGA-SB detector bases ensures a fully supervised, code-compliant system from detection through notification.
What to Check When a Booster Power Supply Fails
When a BPS10A or similar booster power supply generates a trouble condition or fails to operate, a systematic diagnostic approach saves time:
- AC power: Verify that 120 VAC input power is present and the circuit breaker is not tripped. The BPS10A requires a dedicated, labeled circuit breaker per NFPA 72.
- Battery condition: Check battery voltage under load. Sealed lead-acid batteries should be replaced every 3-5 years. A weak or failed battery is the most common cause of trouble conditions.
- NAC wiring: Check each NAC output for opens, shorts, or ground faults. A single wiring fault will trouble the circuit and may prevent other circuits from operating.
- EOL resistors: Verify that end-of-line resistors are correctly installed at the end of each NAC circuit with the correct resistance value.
- Internal fuses: Check internal fuses on the power supply board. Overloads can blow fuses without tripping the circuit breaker.
- Power supply board: If AC input, battery, and wiring all check out but the unit still does not operate, the power supply board itself may have failed.
Alternatives to the BPS10A
For non-Edwards systems or when the BPS10A is not the best fit, alternatives include the System Sensor SpectrAlert series power supplies, Simplex 4009 series power supplies, and Notifier FCPS-24FS series. Selection should be based on output current required, number of NAC circuits, battery backup runtime requirements, and panel compatibility.
Sourcing Booster Power Supplies
Life Safety Consultants stocks the Edwards BPS10A and a range of compatible fire alarm power supply accessories. Browse the Edwards fire alarm parts catalog at LSC for BPS10A availability and related accessories. Contact LSC for guidance on sizing and compatibility for your specific system configuration.
