4 Way Switch Wiring Diagrams
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–Most wiring diagrams on this site include a green dot representing the integrated grounding terminal found in most metal outlet boxes. However, some older metal boxes and most plastic boxes don't have a terminal like this.
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The wiring diagrams on this page make use of 4 way switches, between two 3 way switches, to control lights from three or more locations. A 4-way dimmer diagram is included as well as an arrangement to control the lights from four different points. Check here for 4 way switch troubleshooting and help with 3 ways switches here. For circuits that control lights from two locations only, check the wiring diagrams at this link.
Source at First Switch
In this basic 4 way light circuit the source is at the first switch and the hot connects to the common on that switch. Three-wire cable runs between all the switches and the traveler wires are connected between the two 3-ways and the 4-way. Two-wire cable runs from the last switch to the light fixture and the common on that switch connects to the hot terminal on the light.
Source at the Light
This diagram illustrates wiring for a 4 way circuit with the electrical source at the light fixture and the switches coming after. Two-wire cable is run from the light to SW1 and 3-wire cable runs between all the switches. The hot source is spliced through to the common terminal on SW2 and the hot terminal on the light fixture is connected to the common on SW1. The travelers run from SW1 to T1 on the 4 way and from T2 to the travelers on SW2. Note that the white wire is wrapped with black electrical tape when it is used for hot in these circuits.
Here the source is at SW1 and the light fixture comes immediately after. The source neutral is spliced through to the light fixture. At the light the travelers are splice together and run to the 4-way switch. At the 4-way, the hot wire from the common terminal on SW2 is splice through to the hot on the light fixture.
Source and Light Center
This wiring shows the light fixture and the electrical source between the switches. Three-wire cable runs throughout and the hot source is splice to the common on SW1. The common on SW2 is spliced through to the hot on the light fixture. The travelers from SW1 are spliced at the fixture outlet box to run to the 4 way switch. The 4 way comes right after the light fixture, but before the second 3 way switch, making it fall between the two 3 ways as needed. It could also be installed on the other side of the light and the effect would be the same.
Control Lights from Four Locations
Here two 4 way and two 3 way switches are used to control lights from four different locations. The source is at SW1 and the hot wire is connected to the common terminal. Three-wire cable runs between all switches and 2-wire cable runs from the last switch to the light fixture. The light hot connects to the common terminal on SW2. The two 4-ways are located between the two 3-ways and the traveler wires run from SW1 to T1 on the first 4-way. T2 from that switch is wired to T1 on the second 4way and the output from there to the traveler terminals on SW2.
4 Way Dimmer Wiring Diagram
This is the wiring for a dimmer in a 4 way circuit. To make this circuit work, a 3 way dimmer is used in place of one or both of the standard 3 way switches. A dimmer can be added in this way to any of the circuits on this page. A 3 way dimmer has 4 wires: one common, two travelers and a ground. The common wire is usually black and the travelers red, in any case, the traveler wires will usually be the same color to distinguish them from the common. The stranded wires on the dimmer are spliced to the cable wires from the circuit.
In this diagram the source is at SW1 and the hot is connected to the common terminal there. Three-wire cable runs between the switches and 2-wire cable runs from the dimmer to the light fixture. The travelers from SW1 run to T1 on the 4 way switch and from T2 to the traveler wires on the dimmer. The dimmer common wire is spliced to the hot terminal on the light.
Troubleshooting 4 Way Switch Circuits
If your switches stop working they may be worn out or the screws may have come loose. If you've wired a new switch correctly and the circuit still doesn't work, the switch may be defective. Check that all connections are tight. Check the switch, remove it from the circuit and test for failure with a continuity tester or multimeter set on the Ohms setting.
A 4 way switch must be wired between two 3 ways as shown in the diagrams on this page. A 4 way has five connections: one ground, and 4 circuit terminals divided into two matching pairs. Each pair of terminals should be wired to the traveler wires from one of the 3 way switches. The travelers can be wired to either terminal in a pair, but don't mix up the pairs or the circuit won't work properly.
In order for a 4 way circuit to work, the 3 way switches must be wired properly at the the beginning and end of the path. So be sure that the common terminal on one of the 3 ways is wired to the hot source, and the common on the second 3 way is wired to the the hot terminal on the lights. Check to be sure the traveler wires only connect between the traveler terminals on the switches. Also be sure the neutral from the source is connected to the neutral terminal at the light. A neutral wire will not be used with these switches, although some smart switches may make use of a neutral wire to operate the device.