A drawing of a three-way circuit should include the power source, a two-wire cable with a ground wire connecting to the power source on one end and the light fixture on the other, three-way switches, a three-wire cable with a ground wire connecting the switches, and a light fixture. The diagram varies slightly depending on whether the incoming power is connected to the light fixture or the light switch.
The power source consists of a two-wire cable with a ground wire carrying the standard electric current, 120 volts. A similar cable connects the switches to the light fixture, such as a bulb. If the power source is connected to the light fixture, the cable appears in a single instance in the diagram. The cable appears twice when the incoming power feeds to the switch: to indicate the power source section and the connection from the switch to the light fixture.
Each three-way switch in the diagram has four screw terminals that connect to four wires: a black, white, red and ground wire. The light fixture section includes a fixture box and the fixture. The fixture box shows a connection of the bare wire to the ground, while the light fixture part indicates the connection of the feed cable to the screw terminals on the fixture.