Alarm System Wiring for the Main Panel . Power Wiring. A home alarm system is powered by a low-voltage transformer, which charges a 12-volt backup battery. The battery can usually run the system for a few hours in case of an electrical outage. Alarm system wiring from the transformer location to the main panel should be 4-conductor fire wire, 22-gauge minimum. 480v to 240v Transformer Wiring Diagram Free Wiring Diagram . 480v to 240v Transformer Wiring Diagram - Collections Of 480 Volt to 120 Volt Transformer Wiring Diagram Image. 480v 3 Phase Transformer Wiring Diagram Step Down Tags to 120v. Step Down Transformer 480v 120v Wiring Diagram Trusted Wiring. 480v to 120v Transformer Wiring Diagram Elegant 3 Phase Step Down.