Breaker Off

Breaker Off / Light switches

Dimmer switch wiring, power at the switch

Two cables in the switch box (one from the panel, one up to the light) and one cable in the light box.

Where the power comes in

At the switchtwo cables in the switch boxAt the light, no neutralone 2-wire cable at the switchAt the light, with neutralone 3-wire cable at the switch

What goes in the box

SwitchDimmerSmart switch

The breaker is off: every wire is dead and safe to work on. Tap a switch in the drawing to flip it.

PanelSwitch boxLight boxDimmerLight fixture14/2 NM-B14/2 NM-B BREAKER NEUTRAL BAR GROUND BARLINELOAD
PanelSwitch boxLight boxDimmerLight fixture14/2 NM-B14/2 NM-B BREAKER NEUTRAL BAR GROUND BARLINELOAD

How to tell this is your box

Power is at the switch when the switch box has two cables and, with the breaker on, your tester lights on one of the black wires even with the switch off.

The job, in order

  1. Join the two white wires in the switch box under a wire nut. They pass straight through to the light.
  2. Join the two bare grounds with a pigtail to the green screw.
  3. Put the black from the panel on one screw and the black to the light on the other.
  4. At the light: black to black, white to white, ground to ground.

Every connection, box by box

Read from the same circuit the drawing is made from. A simulator checked it in every switch position: the light turns on exactly when they should, nothing shorts, and every device is grounded.

At the panel

  • The black wire to the switch goes to the breaker.
  • The white wire to the switch goes to the neutral bar.
  • The bare copper wire to the switch goes to the ground bar.

In the switch box

  • The black wire from the panel goes to one black lead.
  • The black wire to the light goes to the other black lead.
  • The white wire from the panel and the white wire to the light join under one wire nut.
  • The bare copper wire from the panel and the bare copper wire to the light join under one wire nut with a ground pigtail to the green lead.

In the light box

  • The black wire from the switch goes to the fixture's black lead.
  • The white wire from the switch goes to the fixture's white lead.
  • The bare copper wire from the switch goes to the fixture's ground.

Parts for this box

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Other boxes on this circuit