How Many Low Voltage Lights On A Transformer March 5, 2019 How Many Lights Can I Connect To My Transformer?. To figure out how many lights you can power with a single transformer, look to the minimum and maximum wattage ratings. www.lightup.com Two Switches One Light DiagramComponent Wire ColorsRelay No Nc Meaning24vdc Relay CircuitBasic Electrical Wiring InstallationVehicle Wiring Information3 Gang Switch WiringW Plan Wiring Diagram