3 Way and 4 Way Wiring for Multiple Lights
–Check local regulations for restrictions and permit requirements before beginning electrical work–
The diagrams on this page illustrate connecting multiple lights in 3 way and 4 way switch circuits. Check below for more details about these circuits and some troubleshooting tips.
Multiple Lights Between 3 Way Switches
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.
Lights Before the Switches
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.
Multiple Fixtures on a 4 Way Switch
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.
About These Circuits
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.
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 device 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 from the source or on the light fixture. These connections can be reversed if it's more convenient, as long as one of the 3 way 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 always be connected from switch to switch. Travelers never connect to a device load or to a source wire. It doesn't matter which traveler terminal is used for which traveler wire, reversing them should make no difference.
Troubleshooting 3 Way 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.
If the switch is good and things still don't work, check the wiring to be sure the hot source is connected to a common terminal and the light fixture hot is connected to a common terminal. 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 not be connected to the switches in these circuits, although some smart switches may make use of a neutral wire to operate the device.