The Auxiliary Power Supply (APS) is a UL 864, 10th-Edition-listed power supply. It is a 24-Vdc filtered-regulated and supervised unit that can easily be configured to provide additional notification appliance circuits (NACs) or auxiliary power for Mass Notification/Emergency Communication (MNEC), as well as life safety applications. The APS contains the circuitry to monitor and charge internal or external batteries. Its steel enclosure has room for up to two 24 ampere-hour batteries. The APS has four Class B (convertible to two Class A) NACs. These can be activated in one or two groups from the APS’s unique dual-input circuits. The APS has a door-mounted AC power indicator LED. The APS also has room for and can power a number of different modules. These can be Signature AA30 or AA50 dual-channel audio amplifiers, GSA-UIO modules and/or GSA-RELs. An MN-BRKT3F can also be installed. This bracket can accommodate an MN-FNS4C2F3 or MN-FNS8C2F3 Ethernet network switch, an MN-FVPN VoIP module and an MN-COM1S Communications module. The APS is available in 6.5 or 10 ampere models. Each output circuit has a capacity of three amperes; total current draw cannot exceed the unit’s rating.