Logo background

Copyright 2024 Electrical101.com All Rights Reserved.

Sitemap

Sitemap

Terms of Use

Privacy

About

Electrical 101

Bolt Bolt

Light Switch Wiring

Question or Comment?

Conventional Light Switch Wiring

With conventional light switch wiring using NM cable, a NM cable supplies line voltage from the electrical panel to a light switch outlet box.

Another NM cable connects from this switch box to the light fixture box. Both line and neutral travel from the switch box to the light fixture box.

Light Switch Wiring Option

With optional light switch wiring, an NM cable supplies line voltage from the electrical panel to a light fixture outlet box.

Another NM cable connects from the light fixture box to the switch box. In the diagram below right, a 2-wire NM cable that connects the light fixture to the switch carries 2 line wires (one line, and one switched line).

The white wire carries the line, the black wire carries the switched line. Since the white wire is hot, a black piece of electrical tape is placed on each end.

This alternate type of wiring is no longer allowed by the NEC as of 2011 if a neutral wire is not present inside each switch box.

Diagrams shown on this page are simplified for clarity. Electrical outlet boxes can have numerous NM cables going in and out. See Actual Switch Box Wiring Diagram.

Typical NM Ground Wire Connections Diagram is shown below.

Placing Black Tape on the White Wire of NM Cable

In a lighting circuit a 2-wire NM cable may carry line voltage on one wire and a switched hot on the other.

Line is usually connected to the white wire, and black electrical tape is wrapped around it. Black tape is also wrapped around the white wires of other NM cables that connect to it.

The black wire on this cable is usually used as a switched hot for the lights.

Line in at switch box

Light Switch Wiring Diagrams

Line in at light fixture

No longer allowed after 2011 NEC (no neutral wire in switch box).

Typical Ground Wire Connections

All ground wires and device terminals are connected together in each outlet box.

In each electrical box, all ground wires are connected together. Ground is also connected to the ground terminal of a device (switch, outlet, light fixture, etc).

Typical Ground Wire Connections Diagram

Black tape on white wire Conventional Light Switch Wiring Diagram Alternate Light Switch Wiring Diagram Typical Ground Wire Connections Diagram