The wiring diagrams on this page make use of 4 way switches, in combination with 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. Check below for details about the wiring for these circuits and 3 ways at these links. 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.
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. We cannot assume responsibility for personal injury or property damage as a result of using the information provided here.
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 drawing the source for the circuit is at the first switch and the hot wire connects to the common on SW1. Three-conductor cable runs between the switches and 14/2 cable runs from SW2 to the light fixture. The common on SW2 is connected to the hot terminal on the light. The travelers run from SW1 to the input on the 4 way and from the output to SW2.
This diagram illustrates wiring for a 4 way circuit with the electrical source at the light fixture and the switches coming after. Two-conductor cable is run from the light to SW1 and 14/3 cable runs between SW1 and SW2. The hot source is spliced through to the common terminal on SW2 and the hot terminal for the light fixture is connected to the common on SW1. The travelers run from SW1 to the input on the 4 way and from the output to SW2.
Here two 4way 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. 14/3 cable runs between all switches and 14/2 runs to the light from SW2. The light hot connects to the common terminal on SW2. The two 4ways fall between the 3ways and the traveler wires run from SW1 to the input on the first 4way. The output is wired to the input 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 of the standard 3 way switches. A dimmer can be added in this way to any of the circuits on this page. These devices have 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.
In this diagram the source is at SW1 and the hot is connected to the common terminal. 14/3 cable runs between SW1 and SW2, 14/2 runs from the dimmer to the light fixture. The travelers from SW1 run to the input on the 4 way and the output is spliced to the traveler wires on the dimmer. The dimmer common wire is spliced to the hot terminal on the light.
The neutral source wire in these circuits will always be connected to the light fixture neutral terminal, either directly, or through splices in each switch box. The ground wire should be spliced to each device, and any outlet box that has a metal grounding terminal. When using the white cable wire to carry current between devices, it should be wrapped with electrical tape to mark it as hot. These diagrams illustrate 15 amp circuits using 14 awg wire. For 20 amp circuits use 12 gauge wire and devices rated at 20 amps.
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, sometimes called the input and the output. 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 ways. 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 load, only. A neutral wire should never be connected to any switch in these circuits.