4-Way Switch Wiring Diagram: Control a Light from Three or More Locations

A 4-way switch (also called an intermediate switch in the UK) lets you control a single light fixture from three or more locations. This is essential for long hallways, large rooms with multiple entrances, and staircases with multiple landings. This guide covers how 4-way switches work, complete wiring diagrams, and step-by-step installation instructions.

What Is a 4-Way Switch?

A 4-way switch has four terminals (plus a ground). It sits between two 3-way switches in a multi-location lighting circuit. While a 3-way switch circuit controls a light from two locations, adding one or more 4-way switches between them extends control to three, four, or more locations.

Terminal Layout

A 4-way switch has:

The switch has two positions:

This cross-over function is what makes multi-location switching possible.

How the Circuit Works

The complete circuit for three-location switching:

  1. Power enters the first 3-way switch box
  2. Two traveler wires run from the first 3-way switch to the 4-way switch
  3. Two traveler wires run from the 4-way switch to the second 3-way switch
  4. Switch leg runs from the second 3-way switch to the light fixture

The 4-way switch either passes the traveler signals straight through or swaps them. Either way, toggling any of the three switches changes the circuit state (on to off, or off to on).

Adding More Locations

For four or more locations, add additional 4-way switches in the traveler wire chain between the two 3-way switches. The rule is:

Wiring Diagram: 3-Location Control

Cable Requirements

Use 12-gauge wire (12/2, 12/3) if the circuit is on a 20A breaker.

Step-by-Step Wiring

At the first 3-way switch (power enters here):

  1. Connect the black wire from the panel (hot) to the common terminal (dark screw)
  2. Connect the red and black wires of the 14/3 cable going to the 4-way switch to the two traveler terminals
  3. Connect white wires together with a wire nut (neutral pass-through)
  4. Connect all ground wires together and to the switch ground screw

At the 4-way switch:

  1. Connect the red and black wires from the first 3-way switch to the two input terminals
  2. Connect the red and black wires going to the second 3-way switch to the two output terminals
  3. Connect all white wires together with a wire nut (neutral pass-through)
  4. Connect all ground wires together and to the switch ground screw

At the second 3-way switch:

  1. Connect the red and black wires from the 4-way switch to the two traveler terminals
  2. Connect the black wire going to the light fixture to the common terminal (dark screw)
  3. Connect the white wires together with a wire nut (neutral pass-through)
  4. Connect all ground wires together and to the switch ground screw

At the light fixture:

  1. Connect the black wire (switch leg) to the fixture's hot terminal
  2. Connect the white wire to the fixture's neutral terminal
  3. Connect the ground wire to the fixture's ground

Wiring Diagram: 4-Location Control

For four locations, add a second 4-way switch between the existing 4-way switch and the second 3-way switch:

  1. 14/3 cable from first 3-way switch to first 4-way switch
  2. 14/3 cable from first 4-way switch to second 4-way switch
  3. 14/3 cable from second 4-way switch to second 3-way switch

Each 4-way switch connects identically: two travelers in, two travelers out, neutrals spliced through, grounds connected.

Alternative Wiring Methods

Power at the Light Fixture

If power enters at the light fixture instead of the switch, the wiring changes:

  1. Hot and neutral enter the fixture box
  2. A 14/3 cable runs from the fixture to the second 3-way switch
  3. Wiring continues as normal between switches
  4. The white wire in the switch leg cable is re-identified with black tape as a hot conductor

Power at a Middle Switch

If power enters at the 4-way switch location:

  1. The incoming hot connects to a traveler wire going to one 3-way switch
  2. Neutral passes through to the fixture
  3. This method requires careful wire identification and is less common

Common Mistakes

1. Wrong Switch Type

A 4-way switch looks similar to a double-pole switch but functions differently. Make sure the switch is labeled "4-way" on the packaging. A double-pole switch will NOT work in this application.

2. Mixed Up Traveler Pairs

Each 4-way switch has input pairs and output pairs. Connecting one wire from each pair to the same side of the switch will not work. Keep the pairs together: both wires from one cable go to one side, both wires from the other cable go to the other side.

3. Reversed 3-Way Switches

The common terminal on a 3-way switch is critical. One common connects to power (hot), the other to the switch leg (to the fixture). Reversing these prevents the circuit from working.

4. Missing Neutral

NEC 2011+ requires a neutral conductor in every switch box for future smart switch compatibility. Ensure the white neutral wire passes through every switch box, even though it does not connect to the switches.

5. Wrong Wire Gauge

Match wire gauge to the circuit breaker: 14 AWG for 15A, 12 AWG for 20A. Never use 14 AWG wire on a 20A breaker.

Smart Switch Alternatives

Modern smart switches can replace 4-way switch circuits:

Testing the Circuit

After wiring:

  1. Turn on the breaker and test each switch location
  2. Each switch should toggle the light independently
  3. If the light does not toggle correctly from one switch:
    • Check that switch is the correct type (3-way or 4-way)
    • Verify traveler connections at that switch
    • Check wire nut connections
  4. If the light does not work at all:
    • Check for voltage at the first switch's common terminal
    • Trace the circuit from power to fixture

NEC Code Requirements

Drawing 4-Way Switch Diagrams

Use CircuitDiagramMaker to create clear 4-way switch wiring diagrams. The DIY symbol pack includes single-pole switches, 3-way switches, 4-way switches, light fixtures, outlets, and breakers. Place your components, connect wires with color coding, and export the diagram as a reference for your installation.

The AI circuit generator can also create multi-way switch circuits -- describe "4-way switch controlling a hallway light from three locations" and the AI generates the complete diagram.

Conclusion

A 4-way switch circuit is a straightforward extension of the 3-way switch concept. The 4-way switch simply swaps or passes through the traveler wires between two 3-way switches. Once you understand this crossover function, you can confidently wire control from any number of locations.

Always turn off power before working, verify with a voltage tester, and follow your local electrical code. When in doubt, hire a licensed electrician.

Create 4-way switch wiring diagrams with CircuitDiagramMaker -- free online tool with residential electrical symbols and smart wire routing.