Light Switch Wiring Diagrams
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–Most wiring diagrams on this site include a green dot representing the integrated grounding terminal found in most metal outlet boxes. However, some older metal boxes and most plastic boxes don't have a terminal like this.
–By code, the number of conductors allowed in a box are limited depending on its size. Conductors include wires, devices like switches and receptacles, and some other metal parts. Check here to calculate the number of conductors allowed in a box before adding new wiring, etc.
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 combo switch/outlet device. Also included are wiring arrangements for multiple light fixtures controlled by one switch, and a split receptacle controlled by two switches.
Wiring a Switch Loop
When the electrical source originates at a light fixture and it's controlled from a remote location, a switch loop is used. The circuit pictured here is wired with 2-conductor cable running from the light to the switch location. The white cable wire in this switch loop is wrapped with black tape and connected to the bottom terminal on SW1 and the hot source at the light. The black wire is connected to the top terminal on SW1 and the hot terminal on the light fixture. The neutral from the source is connected directly to the neutral terminal on the light.
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 remote controlled switch.
Single-Pole Switch to Control a Light
Here a single-pole switch controls the electricity to a light fixture. The source is at the switch and 2-conductor cable runs from there to the light. The source hot wire is connected to the bottom terminal on the switch and the top 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.
Two Switches Control 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-conductor cable is run to each light. One source is spliced to each switch with a pigtail to power the two lights.
Controlling Two or More Light Fixtures
This diagram illustrates wiring for one switch to control multiple lights. The source is at SW1 and 2-conductor 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.
Light Switch Dimmer Diagram
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 with a pigtail. 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-conductor 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.
Light Switch to Control 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-conductor cable runs between SW1 and the outlet. The source is at SW1 and the hot wire is connected to the bottom terminal there. The top terminal is connected to the black cable wire running to the hot terminal on the receptacle and the source neutral is spliced with the white cable wire which runs on to the neutral on the receptacle.
Controlling a Split 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 receptacle and 2-conductor cable runs from there to SW1. 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 which continues on to the bottom terminal on SW1. The black cable wire is connected to the top terminal on the split receptacle and runs to the top terminal on SW1. The circuit neutral wire is connected to one of the neutral terminals on the receptacle, it doesn't run to the switch.
In this updated diagram 3-conductor cable runs between the receptacle and switch, and the red cable wire is used to carry the hot source to the bottom terminal on the switch. The neutral from the source is passed 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.
Double Split Receptacle Outlet
In this circuit a split receptacle is controlled by two separate switches. With this arrangement two lamps can be plugged into the same receptacle 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-conductor cable runs from there to the receptacle, 2-conductor cable runs from the receptacle to SW2. The source hot wire is spliced to the bottom terminal on SW1 and to the red cable running to the receptacle. The top terminal is connected to the black cable wire, and the source neutral is spliced to the white wire which continues on to one of the neutral terminals on the receptacle, it doesn't matter which, only one connection is needed with the neutral wire.
At the receptacle the black cable wire from SW1 is connected to one of the hot terminals and the red wire is spliced to the white wire on the 2-conductor cable running to SW2. The white wire is wrapped with electrical tape to mark it as hot. The black wire is connected to the second hot terminal on the receptacle and to the top terminal on SW2 at the other end.
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 extra, red wire serves that purpose for the second switch.
3-Way Switched Receptacle Outlet
Here two 3 way switches control a wall receptacle 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.
Wiring for a Combo Switch and Outlet
A combo switch/receptacle is handy when you need both, but you only have one outlet box available. Like the split receptacles above these devices makes use of a removable connector between the two, hot terminals to divide the device when needed. When intact and wired to one hot source wire, the combo device can be used to turn a light off and on, while the receptacle will be constantly hot.
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 switch output to the hot on the light fixture. The source neutral wire is spliced to the neutral on the receptacle half of the combo device and to the white cable wire. At the light it connects to the neutral terminal.
This is another option for wiring a combo device where two 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 and to the input side of the switch at the other end. The white neutral from the source is connected directly to the light fixture. The red wire from the switch output goes to the hot terminal on the light.
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.