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Standard Single-Pole Light Switch Wiring

The simplest and most common light switch is actually referred to by hardware dealers and electricians as a “single-pole light switch.” With a single-pole light switch, flipping the lever up completes the circuit, turning lights or appliances on, and flipping it down breaks the circuit, turning lights or receptacles off.

A single-pole switch has two brass terminal screws on the side that receive the black (“hot”) wires of the circuit. One black wire comes from the power source and the other goes to the light(s).

When you turn the switch off, it interrupts the electricity that flows through the black wire from the power source to the fixture. For this reason, the two main terminals are connected to black wires. The bare ground wire—if there is one— is connected to the green grounding screw on the switch.

The wiring diagrams on this page can help you plan the proper way to wire for a light switch. Always turn off the power to the circuit before working on wiring. See How to Turn Off Your Home’s Electricity.

Again…the circuit’s white wires bypass the switch UNLESS…a white wire has been converted to do the job of a black wire. Many homes are wired with 3-wire non-metallic cable (such as the brand Romex®) that consists of one black wire, one white wire, and one bare or green grounding wire.

single pole light switchLeviton

Single-pole light switch controls lights from one location.

When wiring switches, this type of cable may be used as a switch leg—where you need two black wires to go from the switch to black wires located at the light or at an intermediate electrical box.

As shown in the diagrams below,  you can paint a couple of inches of the end of the white wire black—or wrap it with black electrical tape—to indicate that it is being used as a black wire. Electrical codes can vary on this practice.

Light Switch Circuit Diagram

Standard Single-pole Light Switch Circuit Diagram

Single-Pole Switch Wiring Diagrams

The right way to wire a single-pole switch depends upon where the switch is located relative to the light. The diagrams below show the various options.

switch wiring diagram 1

Proper wiring for a single-pole switch that controls a light from the center of a circuit.

 

switch wiring 2

Easiest to wire is a single light that occurs at the end of a circuit.

 

switch wiring 3

When an un-switched circuit continues from a switched light, this is how to wire it.

A dimmer switch is wired the same way as a single-pole switch. In this illustration, you can see the red hot “lead” wires of the dimmer are connected to the inbound black wire from the electrical source (the electrical panel) and the black wire that goes to the light fixture’s black wire which, in this case, is a white wire that has been taped with black electrical tape.

dimmer switch wiring

Dimmer switch interrupts the black wire that goes to the light fixture.

The type of switch that will operate hallway lights from either end of the hallway is called a three-way switch; it has an extra terminal. For information about the different ways to wire this type of switch, please see How to Wire Three-Way Switches.

Three-way SwitchGE

Three-way Switch

 

About Don Vandervort
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Don Vandervort has developed his expertise for more than 30 years, as Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996.

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