The following is a doorbell wiring diagram illustrating the ground cable 120VAC cable connected to a transformer. As you can see here, this junction box (that contains the transformer) is the key to playing the ring. When someone presses the bell, the circuit will get activated. More simply, you can see two wires exit a transformer, and two wires travel to each doorbell switch. Once the switch is activated, the transformer will supply a low-voltage power supply for the home or office's centralized alarm system, including the fire-safety system (if connected). With EdrawMax Online, creating such a wiring diagram is easy as all you need is the right data, and the system will provide you with the right diagramming tools.