The Altronix AL400UL-PD4R Fire Power Supply converts a 115 V, 60 Hz input to either 4 A of continuous supply current at 12 VDC or 3 A of continuous supply current at 24 VDC. The supply current is distributed through four fuse-protected, Class 2 Rated, power-limited outputs.Battery Considerations The power supply accommodates up to two 12 VDC, 7 Ah standby batteries and automatically switches to battery power if AC input power fails. When batteries are not used, a loss of AC power results in a loss of output voltage. When batteries are used, they must be lead-acid or gel type.Mounting Considerations Mount indoors in areas protected from rain or moisture.Wiring Considerations Use 14 AWG (ISO 2.5 mm2 ) or larger wiring for all power connections (battery, DC output, AC input). Use 22 AWG to 18 AWG (ISO 0.34 mm2 to 0.75 mm2 ) wiring for power limited connections (AC fail, low battery reporting).