One of them comes from the supply, and the other takes power onward to another point-of-use. The red wire is the “switched-hot” (energized when you want the light to be on). That coincidentally matches the preferred color code; usually you have to re-mark wires with colored tape lol.

Why does light switch have 3 wires?

A 3-wire NM connects the traveler terminals of the first and second 3-way switch together. Traveler wires are interchangeable on each switch. The common terminal of the second 3-way switch connects to the light fixture(s). The white neutral wires are connected together in each switch box.

Why do I have 4 wires on my light switch?

The A wire (black) connects to the hot (black) wire from the power source. The B wire (blue) connects to the other wire from the load. The C wire (red) is not used and is capped with a wire nut. The D wire (green) connects to the ground.

What is a traveler wire?

The traveler wires run between the two 3-way switches, offering two potential pathways to complete the circuit and send power onward to the light fixture. It makes no difference which traveler wire goes to which traveler terminal on the switch; the traveler terminals are interchangeable.

Why would a 3-way switch have 4 wires?

4-Wire Cable

When wiring a 3-way switch circuit, all we want to do is to control the black wire (hot wire) to turn on and off the load from 2 different locations. The diagram below will give you a better understanding how this circuit is wired.

What is the common wire on a 3-way switch?

Quote from Youtube video: This is called a three-way switch at one switch there's a hot wire. And two traveler wires at the other switch there's a load wire. And the other end of the same two travelers a three-way switch has a

How do you bypass a 3 wire switch?

3 Answers

  1. replace that switch with a single-pole switch.
  2. connect either of the “traveler” wires to the load side.
  3. remove the other (unwanted) switch and connect the traveler wire used in step-2 to the “switched hot” wire that goes to the lights.
  4. the unused “traveler” wire is abandoned.

What is 4 wire used for?

Four-wire is used for “two-way” circuits, and for cases where two circuits are running to the same place (independent control of a ceiling fan and its lights, for example). In the US color coding conventions, red is the “second hot” needed for these applications.

What are the 4 wires in house wiring?

A 4-wire circuit will have a red wire, black wire, white wire and a ground wire. The ground wire can be green or bare (without insulation).

Why are there 4 wires in my ceiling light?

In order for the light to be controlled by its own switch, the wiring between the switch and the fan unit needs a fourth wire, a red wire, to carry power to the light kit.

What is the white wire in a 3-way switch?

White wire: This is the neutral wire, and its purpose is to complete the electrical circuit. In all electrical circuits, power must return to the energy source, and this is the job of a neutral wire. Ground wire: The ground wire is a bare copper wire or a green wire, and its purpose is to provide a measure of safety.

What is the red wire in a 3-way switch?

Figure A: 3-Way Switch Wire Diagram — Power to Light Fixture

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 is the black screw on a 3-way switch?

This screw serves one of two purposes depending on where it is positioned in the circuit run: Either it accepts the incoming black (hot) wire from the power source, or it connects to the black (hot) wire that leads onward to the light fixture.

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

Tighten the terminal screws. Connect the ground wire to the green screw, then connect the wire marked common to the black or dark colored screw. Connect the two remaining traveler wires to the two brass or light colored screws.

How can I tell which wire is hot on a 3-way switch?

The 3-way wire is located on the left of the switch then runs to the right side. The left part of the switch is where the black “hot” wire enters. While the black and red wires carry the output from terminals to the left switch, and the white one carries ground.

What color wire goes to the black screw on a light switch?

yellow cable

The black wire goes up to the light through the yellow cable. The green ground screw on the switch is used to connect the two grounds. The black screw can get either the wire from the electrical panel or the wire going to the light.

Does it matter which wire goes where on a light switch?

It doesn’t matter as long as you do it the same on both switches. So, if you connect it to the upper right terminal on one switch, connect it to the upper right terminal on the other switch. Connect the second traveler wire to the terminal opposite the red wire terminal.

What color is the ground wire on a light switch?


Green, green with yellow stripe, or bare copper are ground wires. Black wires are hot wires that run to the electrical outlet from the switch.

Is black screw hot wire?

Basic Wire Color-Coding

A black or red-hot wire usually connects to a brass-colored screw terminal or black wire lead on electrical devices. A white neutral wire usually connects to a silver-colored terminal or white wire lead.

Which is the hot screw on a light switch?

A single-pole switch has two brass terminal screws on the side that receive the black (“hot”) wires of the circuit. One black wire comes from the power source and the other goes to the light(s).

What color screw does the black wire go to?

Black (Hot) goes on the smaller prong side or white to silver screws, black to gold screws. Ground (bare wire) to green.