What is a Switch Loop Wiring Diagram and How is it Used?
A Switch Loop Wiring Diagram is a schematic representation that illustrates how power is routed to a light fixture through a wall switch. In a standard setup, power originates from the electrical panel, travels to the switch box, then goes to the light fixture, and finally returns to the switch box to complete the circuit. This creates a "loop" where the switch acts as an interruption to control the flow of electricity to the light.- The Power Source: The circuit breaker in your electrical panel supplies the hot (usually black) and neutral (usually white) wires.
- To the Switch Box: The hot wire travels from the panel to the switch box.
- Through the Switch: Inside the switch box, the hot wire is connected to one terminal of the light switch. The other terminal of the switch is connected to a wire that will go to the light fixture.
- To the Light Fixture: This wire carries the switched hot power to the light fixture.
- Back to the Switch Box: At the light fixture, the switched hot wire connects to the fixture's hot terminal. The neutral wire from the power source is connected directly to the fixture's neutral terminal. The ground wire is also connected to the fixture and to the switch box.
- Completing the Loop: A wire is then run from the light fixture back to the switch box. This wire is connected to the neutral terminal of the light fixture and then to the neutral wire that originally came from the power source. The switch loop essentially "borrows" the neutral from the light fixture's location to return power to the switch.
| Symbol | Represents |
|---|---|
| Solid Line | Hot Wire |
| Dashed Line | Switched Hot Wire |
| Dotted Line | Neutral Wire |
| Circle with "SW" | Light Switch |
| Circle with "L" | Light Fixture |