3-Way Switch Variation Wiring

Placing Black Tape on the White Wire of NM Cable

In a lighting circuit a 2-wire NM cable may carry line voltage on one wire and switched hot on the other.

Line is usually connected to the white wire, and black electrical tape is wrapped around it. Black tape is also wrapped around the white wires of other NM cables that connect to it.

The black wire on this cable is usually used as a switched hot for the lights.

3-Way Switch Variation Wiring Diagrams, NM Cable

Line enters light fixture outlet box, then to left 3-way switch box.

Line and light fixture connects to right switch outlet box

Line enters light fixture outlet box, then to right 3-way switch box.

Question or Comment?

3-Way Switch Wire Colors

There is no standard for wire colors on 3-way switch travelers. The colors will vary depending on whether NM cable or conduit was used. With NM cable, the wire colors for travelers will be black and red using 3-wire cable. With conduit, the wire colors for travelers could be any color.

3-Way Switch Wiring Variation Diagrams

In the first two diagrams below, the white wire (neutral) from the panel connects to the neutral of the light fixture in the light fixture outlet box.

The black wire from the panel connects to the white wire on the NM cable that goes to the first 3-way switch box. This wire has black tape wrapped around it to indicate line voltage.

The hot side of the light fixture connects to the switched black wire on the NM cable that goes to the first switch box.

The common terminals from each switch are connected together.

One traveler from each switch is connected together and to line voltage.

The other travelers from each switch are connected together and to the load(s).

Diagrams shown on this page are simplified for clarity. Electrical outlet boxes can have numerous NM cables going in and out. Actual Switch Box Wiring Diagram.

Ground connection diagram is shown separately.