How to Wire a 3 Way Switch

With a three-way switch, three wires connect the pair of switches—two black “traveler” wires and a third “common” wire. When the circuit’s power is turned on, any of these may be “hot,” depending upon how the switches are toggled.

What color wire goes to the black screw on a 3-way switch?

Black screw terminal: The black (or darkest in color) screw attaches to the black common wire from the 14/2 cable. The terminal may be labeled COM. Green screw terminal: The green screw is the ground terminal.

What happens if you wire a 3-way switch wrong?

Usually when a 3-way switch fails, lights can be toggled on and off at one switch, but not the other. If one of the two 3-way switches toggles the light(s) on and off, the other 3-way switch has probably failed.

Where does the neutral wire go on a 3-way switch?

The other wires in a circuit with 3-way switches are the neutral (usually white) and ground (usually bare copper or green). The neutral wire bypasses both 3-way switches but connects to the light fixture. The ground connects to the ground terminal on each switch and to the light fixture.

Which wire is hot on 3-way switch?

The black hot wire connects to the far right switch’s common terminal. Red and blue wires link traveler terminals of both switches. The red wire, which is connected to the first switch’s common terminal, leads back to the fixture.

What color wires go on a 3-way switch?

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.

What are the terminals on a 3-way switch?

A 3-way switch is larger than a single pole switch and has three screw terminals for wiring connections, plus a ground. Two of these take traveler wires that go from one switch to the other. For the third terminal, one switch is connected to the hot supply wire while the other switch is joined to the light.

What happens if you mix up line and load wires?

If the load and line wiring gets messed up, a ground fault (radio in the tub) won’t trip the GFCI. There is no protection; there’s only the appearance of protection. The GFCI is a booby trap. I’m sorry to say, we find this very problem about once a week.

Can wiring a light switch wrong cause a fire?

Usually, a broken or failing light switch isn’t a fire hazard itself, but it can overheat if the contacts or the switch wear down. Sometimes a bad light switch can cause other components on the circuit, such as a bulb, to become a fire hazard by causing an intermittent current.

Will a 3 way switch work without a ground?

The green screw attached to the metal strap of the switch is always for the ground wire (this is the bare copper or green insulated wire within the circuit). Grounding screws on switches were not always required, so if you are replacing an old three-way switch, you may find one without the grounding screw.