The diagrams on this page illustrate connecting multiple light fixture in 3 way and 4 way switch circuits. Check below for more details about these circuits and some troubleshooting tips.
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 circuit, two fixtures are shown but more can be added by duplicating the wiring arrangement between the lights for each one added. Here the source is at SW1 and 3-wire cable runs from there to L1. Two, 2-wire cables run between the fixtures, and 3-wire cable runs from the last one to SW2.
At the beginning of the circuit the hot source is connected to the common terminal on SW1. The neutral is spliced to the white cable wire and then spliced to the neutral terminal at L1, along with the white 2-cable wire running to L2 where it connects to the neutral terminal. The traveler wires are run using the other 2-wire cable between the lights and continue on to the traveler terminals on SW2. They don't connect to the fixtures at all.
This diagram illustrates another multiple light circuit controlled by 3 way switches. Here the source and the fixtures come before the switches. As with the other diagrams on this page, more lights can be added by duplicating the arrangement between the fixtures.
A 3-wire cable runs from L1 to L2, 2-wire cable runs from there to the first switch, and 3-wire cable runs between SW1 and SW2. The source hot is spliced to the black wire running between the lights and at the last light, it is spliced to the black wire running through to the common on SW1. The white wire is marked black and spliced to the black wire running to the common on SW2.
Back at the lights the source neutral is connected to the neutral terminal on L1 and spliced with the white wire running between the fixtures. At each light it's connected to the neutral terminal. At SW1 the red and white wires from the 3-wire cable running between switches function as the travelers with the white marked for hot using black tape or paint.
This drawing shows the wiring for multiple lights in a 4 way circuit with the source and fixtures coming before the switches. More lights can be added to this circuit by duplicating the wiring shown here for each additional fixture. Here 3-wire cable runs between L1 and L2, 2-wire cable runs from the last fixture to SW1, and 3-wires runs between SW1 and SW2.
At the lights the hot source is spliced to the black wire at each fixture box, at the last fixture it is spliced to the black wire running to the common on SW1. The neutral from the source is connected to each light fixture with a pigtail and run on to the next light.
At SW1 the white wire is wrapped with black tape and run through to the common on SW2 using the white wire at each switch. At the lights the white wire from SW2 is spliced to the hot terminal on each fixture. The black and red wires running between the switches serve as the travelers for the circuit. At the 4 way the travelers from SW1 connect to T1 and T2 connect to the travelers for SW2.
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.
Three way switches have 3 terminals to carry circuit electricity and one terminal for a ground wire. Of the three circuit terminals, one is called the common and the other two are known as travelers. The common terminal may be labeled and is usually a different color than the traveler terminals. Depending on the manufacturer, the travelers may be on opposite sides of the switch or the two terminals may be on the same side. In any case, the common terminal will be distinguished from the travelers in some way.
The common terminals will always be connected to a hot wire, either the hot source or the device hot. These connections can be reverse if it's more convenient, as long as one of the 3 way switch common terminals connects to the hot source and the other one connects to the hot on the load, these circuits will work properly. The traveler terminals will be connected from switch to switch. Travelers never connect to a device load or to a source wire. It doesn't matter which traveler terminals are used for which traveler wire, reversing them should make no difference.
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.
If the switch is good make sure the hot wire from the source is connect to the common terminal on one of the 3 way switches and the hot wire to the fixture is connected to the common on the other. Likewise, be sure the traveler terminals are connected between switches only, and not to any hot wires or the load. 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.
