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Light Switch Wiring
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-
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-
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).
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
