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Electrical Wire and Cable

How to Wire a Light Switch - Diagram 1

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Summary: Easy to Understand Light Switch Wiring - Fully Explained Light Switch Wiring with Diagrams and Pictures with Step-By-Step Instructions to Guide You.

Understanding the Basic Light Switch for Home Electrical Wiring

Please Note: To illustrate the wiring of these switches, Switch Boxes and Fixture Boxes are not shown but are obviously required for every application.
These diagrams are shown as using the Romex wiring method.

These Romex cables contain a ground conductor which is required for all applications as well.
The ground conductors are always bonded together to insure the integrity of the ground path.

If you are using metal boxes, the ground conductor must be attached to each box by using a threaded ground screw or provided attachment. The frames of the switches which have a ground screw are to be attached to the ground conductor as required.

  • How to Wire a Single Switch


  • Featuring Wiring Diagrams for Single Pole Wall Switches Commonly used in the Home.

Explanation of Wiring Diagram #1

  • Switch wiring shows the Power Source (Power In) starts at the switch box.
  1. Circuit electrical wiring enters the switch box
  2. The Black Wire - Power In (source) attaches to one of the switch screw terminals
  3. Fixture wiring exits the switch box
  4. The Black Wire - Power Out wiring attaches to the other switch screw terminal
  5. The White Neutral wires splice together
  6. The ground wires splice together and bond to the switch and the box

NOTE: Switched 'White' wires are shown in a different wiring diagram

  • Single Switch Applications

  • Ceiling Light Fixtures
  • Switch Controlled Outlet
  • Half-Hot Wall Outlet
  • Ceiling Fan and Light
  • Single Wall Switch Types and Styles

  • Standard Toggle Switch
  • Flat Rocker Switch
  • Dimmer Switch
  • Some Home Automation Switches
Single Pole Switching Diagram


Wiring a Single Pole Switch

Question: Your example shows 2 wire Romex but most Romex I have seen has three wires one white-one black and an un-shrouded copper ground wire. What is the correct connection for this ground wire?

Answer: As explained in this page above: These Type-NM cables contain a ground conductor which is required for all applications as well. The ground conductors are always bonded together to insure the integrity of the ground path.

More about Wiring Switches

Questions about Wiring Switches

How is the Wiring for a New Light Switch and Fixture added to an Existing Switch?

  • I have an existing light switch, and I want to add a second switch for a new light that will be operated separately. The power comes into the switch which operates a single light at the end of the circuit. I know I have to change the gang box and I’m fine with running cable and installing plates but I’m not clear on the best way to add the wiring. Is there a simple way to do this or should I get an electrician?

This electrical wiring question came from John in Lexington, Kentucky.

Adding a Light Switch and Fixture to an Existing Switch

  • The task of installing additional wiring for a light switch and new light fixture will depend on available access to the proposed location. Hiring a qualified electrician will ensure that the installation is performed correctly where the existing circuit wires will be identified, and new circuit wiring will be extended to the new light switch and then out to the new light fixture. The method used to install the new wiring will depend on the wall structure and location in the home. Special attention will be given to the existing circuit capacity, the wire type and size, as well as making sure the additional wiring is protected and installed according to all the electrical codes that will apply.

Learn more about wiring switches

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Complete Guide to Home Electrical Wiring
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