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 dimmer circuit is included as well as an arrangement to control the lights from four different points. Also check here for 4 way switch troubleshooting and help with 3 ways circuits here. To control lights from two locations only, use the wiring diagram at this link.
It is the responsibility of the user of this information to know and understand the NEC (National Electrical Code) as it applies to them, as well as any local regulations or laws that may pertain. While many jurisdictions do adopt the standards of the NEC, some may have requirements in addition to, or exemptions from those standards. We cannot assume responsibility for personal injury or property damage as a result of using the information provided here.
The information on this page is intended to aid in electrical wiring projects that become necessary when doing DIY home improvements and repairs. Some of the diagrams here are for older circuits that may not adhere to the latest code updates. When running a new circuit be sure to use the latest approved wiring arrangements.
In the diagrams on this website the brass colored terminals on the devices represent the hot side of the circuit and the silver colored terminals represent the neutral side. Green is used to denote ground wires and terminals. Not all outlet boxes or older devices will have a grounding terminal. When running new wiring the ground wires should be spliced with a short piece of wire to connect to each device that has a grounding terminal, and to any grounding terminals in the outlet boxes. Also be aware that the white wire may be use to carry current in some household circuits, in these cases it should be marked with black electrical tape to indicate it is hot.
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.
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.
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.
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.
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.
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 and test suspect switches 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. The terminal pairs may be different colors or they may be labeled to distinguish them from each other. 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 load. 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 usually not be connected to the switches in these circuits, although some remote controlled switches may make use a neutral wire to operate the radio receiver for the remote.