Light Switch Wiring Diagrams

This page contains wiring diagrams for household light switches and includes: a switch loop, single-pole switches, light dimmer, and a few choices for wiring a outlet switch combo device. Also included are wiring arrangements for multiple light fixtures controlled by one switch, two switches in one box, and a split receptacle controlled by two switches, plus more.

When the electrical source originates at a light fixture and is controlled from a remote location, a switch loop is used. This circuit is wired with a 2-wire cable running from the light to the switch location. The neutral from the source is connected directly to the neutral terminal on the light and the source hot is spliced with the white loop wire. The white wire is marked black on both ends to identify it as hot. At SW1 it is connected to one of the terminals. The black loop wire is connected to the other terminal and at the light, to the hot terminal on the fixture.

This is an updated version of the first arrangement. Because the electrical code as of the 2011 NEC update requires a neutral wire in most new switch boxes, a 3-wire cable runs between the light and SW1. The red and black are used for hot and the white neutral wire at the box allows for powering a timer, remote control, or other programmable device.

Here a single-pole switch controls the power to a light fixture. The source is at the switch and 2-wire cable runs from there to the light. The source hot wire is connected to one terminal on SW1 and the other terminal is connected to the black cable wire running to the light. The neutral wire from the source is spliced to the white cable wire and continues on to the light. At the light, the white wire connects to the neutral terminal and the black wire connects to the hot terminal.

Wiring Two Switches for Two Lights

Here two switches are wired in the same box to control two separate lights. The source is at the box and a 2-wire cable is run to each light. The source hot is spliced to one terminal on SW1 and SW2 with a pigtail. The other terminals are connected to a black wire running to a light fixture. At the box the white neutral and ground wires are spliced to each set of wires running to the lights.

Multiple Light Wiring Diagram

This diagram illustrates wiring for one switch to control 2 or more lights. The source is at SW1 and 2-wire cable runs from there to the fixtures. The hot and neutral terminals on each fixture are spliced with a pigtail to the circuit wires which then continue on to the next light. This is the simplest arrangement for more than one light on a single switch.

A dimmer, or rheostat makes it possible to vary the current flowing to a light fixture thereby varying the intensity of the light. The dimmer switch will have stranded wires that must be sliced to the solid cable wiring in a pigtail fashion. A device like this should only be used with an incandescent light fixture and not with a ceiling fan or other motor. See wiring a speed controller for wiring a rheostat to control fan speed.

To wire this circuit 2-wire cable runs from the dimmer to the light. The source is at the dimmer and the hot wire is spliced to one hot wire on the device. The other wire from the dimmer is spliced to the black cable wire which runs on to the hot terminal on the light. The source neutral wire is spliced to the white cable wire which continues on to the neutral terminal on the light.

Wiring a Switch to a Wall Outlet

Here a receptacle outlet is controlled with a single-pole switch. This is commonly used to turn a table lamp on and off when entering a room. In this diagram, 2-wire cable runs between SW1 and the outlet. The source is at SW1 and the hot wire is connected to one of the terminals there. The other terminal is connected to the black cable wire running to the hot terminal on the receptacle. The source neutral is spliced in the switch box with the white cable wire running to the neutral on the receptacle.

Wiring Diagram for a Split Outlet

This diagram illustrates the wiring for a split receptacle with the top half controlled by SW1 and the bottom half always hot. The receptacle is split by breaking the connecting tab between the two, brass colored terminals. The tab between the neutral, silver terminals should remain intact.

Here the source is at the outlet and 2-wire cable runs from there to SW1. The circuit neutral wire is connected to one of the neutral terminals on the outlet, it doesn't run to the switch. The hot source is spliced to a pigtail that connect to the bottom, always-hot half on the receptacle and to the white cable wire running to SW1. The white wire is marked black on both ends to identify it as hot. The black cable wire runs to the SW1 connecting it to the hot on the top half of the split outlet.

In this updated diagram 3-wire cable runs between the receptacle and SW1 and the red cable wire is used to carry the hot source to one of the terminals. The white neutral from the source is spliced in the receptacle box and run through to the box at SW1 where it is capped using a wire nut. This represents a change in the NEC code that requires a neutral wire in most new switch boxes. If you are running a new circuit, check the electrical code to understand this and any other updates to the required procedure.

Wiring a Double Split Switched Outlet

In this circuit a split receptacle is controlled by two separate switches. With this arrangement, two lamps can be plugged into the same outlet and each can be controlled separately from two different locations.

Here again the connecting tab between the receptacle terminals is broken off and the neutral tab remains intact. The source is at SW1 and 3-wire cable runs from there to the outlet, 2-wire cable runs from the outlet to SW2. The source hot wire is spliced with a pigtail to one terminal on SW1 and to the black wire running to the receptacle box. At that box, the black wire is spliced with the white wire running to one terminal on SW2. The white wire is mark black on both ends to identify it as hot.

The second terminal on SW1 is connected to the red wire running to the hot terminal on the top half of the split receptacle. The source neutral is spliced to the white wire running to one neutral terminal on the receptacle. It doesn't matter which one, only one connection is needed.

At the receptacle, the black wire running to SW2 is connected to the bottom hot terminal and at the other end to the remaining terminal on SW2.

In this updated diagram, 3-wire cable runs between the receptacle and SW2 to allow for splicing the neutral source through to the second switch box.

Here the white is not used for hot but instead the black wire serves that purpose for SW2. The red wire is connected to the hot on the bottom half of the receptacle and to the remaining terminal at SW2.

3 Way Switched Outlet Wiring

In this diagram, two 3 way switches control a wall receptacle outlet that may be used to control a lamp from two entrances to a room. This circuit is wired the same way as the 3 way lights at this link.

Three-wire cable runs between the switches and the outlet. The source is at the SW1 where the hot is connected to the common terminal and the neutral spliced through to the neutral on the outlet. The red and black wires running from SW1 to the outlet are used as travelers. At the outlet, the travelers are spliced to run to SW2 using the red and white wires in that cable. The white wire is marked black on both ends to identify it as hot. The black wire to SW2 is connected to the hot on the receptacle and to the common on SW2 at the other end.