Light Switch Wiring Diagrams

by: Dale Cox

By code, the number of conductors allowed in a box are limited depending on box size and wire gauge. Calculate total conductors allowed in a box before adding new wiring, etc. Check local regulations for restrictions and permit requirements before beginning electrical work. The user of this information is responsible for following all applicable regulations and best practices when performing electrical work. If the user is unable to perform electrical work themselves, a qualified electrician should be consulted. How to Read These 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 on one box, and a split receptacle controlled by two switches.

Wiring a Switch Loop

light switch loop wiring diagram

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 switch loop 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.

light switch loop wiring diagram NEC 2011

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 switch. The red and black are used for hot and the white neutral wire at the switch box allows for powering a timer, remote control, or other programmable switch.

Wiring a Single-Pole Light Switch

wiring diagram for a light switch with the source at the switch

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 a switch terminal and the other terminal is connected to the black cable wire. 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.

Wiring Two Switches for Two Lights

wiring diagram for two switches controlling two lights

Here two switches are wired in the same box to control two separate lights. The source is at the switch box and a 2-wire cable is run to each light. One source is spliced to each switch with a pigtail to power the two lights.

Multiple Light Wiring Diagram

wiring diagram for one switch controlling multiple lights in row

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.

Dimmer Switch Wiring Diagram

wiring diagram for a single dimmer switch to a light

A rheostat, or dimmer, 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

wiring diagram for a switched 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 switch 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

wiring diagram for a split switched receptacle 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.

wiring diagram for a split switched outlet NEC 2011

In this updated diagram, 3-wire cable runs between the receptacle and switch and the red cable wire is used to carry the hot source to the switch. The neutral from the source is spliced through to the switch box using the white wire and in this diagram, the white wire is capped with 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

diagram for two switches controlling one split 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 there to SW2. The source hot wire is spliced with a pigtail to SW1 and to the black wire running to the receptacle box. At the box, the black wire is spliced with the white wire running to SW2. The white wire is mark black on both ends to identify it as hot.

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

From the receptacle, the black cable wire running to SW2 is connected to the hot terminal on the bottom half and to the switch at the other end.

diagram for two switches controlling one split outlet NEC 2011

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 the second switch. The red wire to SW2 is connected to the hot on the bottom half of the receptacle and to the switch at the other end.

3 Way Switched Outlet Wiring

wiring diagram 3 way switched outlet

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.

Wiring for an Outlet and Switch Combo

An outlet switch combo device is handy when you need both but you only have one box available. Like the split receptacles previously mentioned, these devices make use of a removable connector between the two hot terminals to divide it when needed. When intact and wired to one hot source wire, the combo can be used to turn a light off and on while the receptacle will be constantly hot. Check here to see wiring diagrams for a gfci outlet switch combo when you need a device like this with ground fault protection in a kitchen, bathroom, or laundry room.

wiring diagram for an outlet switch combo and light fixture

This diagram shows the first wiring option for this device. In this arrangement, the connecting tab between the hot terminals remains intact. The source is at the device and the hot is connected directly to one of the hot terminals, it doesn't matter which one. Two-wire cable runs from the combo to the light fixture and the switch output is connected to the black wire running to the fixture hot terminal. The source neutral wire is spliced to the neutral on the receptacle half of the combo device and to the white cable wire running to the light. At the light, it connects to the neutral terminal.

wiring diagram for a receptacle and outlet switch combo in the same box

If you have a second device in the same box with the combo switch, you can wire them together as illustrated in this diagram. We use a receptacle here but any device such as a switch, timer, etc. will be wired in the same way. The tab on the combo remains intact and the source hot is spliced with a pigtail to the hot terminals on each device in the box. The source neutral is spliced with a pigtail to the two devices and to the white wire running to the fixture neutral terminal. The combo switch output is connected to the black wire running to the fixture hot terminal.

wiring a outlet switch combo with two electrical sources

This is another option for wiring a combo device where two electrical sources are used. In this arrangement, the connecting tab between the hot terminals on the device is broken off to separate the two. The switch controls a light and the receptacle half of the combo device is always hot.

Source 1 comes in at the light fixture and a 3-wire cable is run from there to the switch half on the device. The hot from the source is spliced to the black wire running to the combo and to the input side of the switch. The white neutral from the source is connected directly to the light fixture. The red wire from the light is connected to the output on the switch and to the hot terminal on the light at the other end.

Source 2 comes in at the combo device where the hot and neutral wires are connected to their corresponding terminals on the receptacle half of the device.

wiring diagram for an outlet switch combo to control itself

Lastly, the combo switch can be used to control the built in receptacle itself, allowing it to function as a switched outlet. This is handy if you want to use the switch to control a light fixture or other device plugged into the combo. Here the tab between the two halves is removed and the circuit hot is connected to the input side of the switch. The switch output is sent to the hot side of the receptacle using a short jumper wire of the same gauge. The circuit neutral is connected to the neutral side of the receptacle outlet.