Breaker Off

Breaker Off / 3-way and 4-way switches

3-way dimmer wiring, power at the switch

In the first switch box, a 2-wire cable from the panel and a 3-wire cable to the other switch. In the second switch box, that 3-wire cable and a 2-wire cable up to the light.

Where the power comes in

At the first switchthe panel cable is in a switch boxAt the lightthe panel cable is in the light box

What goes in the box

3-way switches3-way dimmerAdd a 4-way

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

PanelFirst switch boxSecond switch boxLight box3-way dimmer3-way switchLight fixture14/2 NM-B14/3 NM-B14/2 NM-B BREAKER NEUTRAL BAR GROUND BARCOMMONTRAVELERTRAVELERCOMMONTRAVELERTRAVELER
PanelFirst switch boxSecond switch boxLight box3-way dimmer3-way switchLight fixture14/2 NM-B14/3 NM-B14/2 NM-B BREAKER NEUTRAL BAR GROUND BARCOMMONTRAVELERTRAVELERCOMMONTRAVELERTRAVELER

How to tell this is your box

The first switch is the box where the 2-wire cable from the panel comes in. With the breaker on, that cable's black wire is live however the switches sit (a traveler can be live too, so go by the cable). That black goes to the dark COMMON screw.

The job, in order

  1. First switch: the black from the panel goes to the dark COMMON screw.
  2. Black and red in the 3-wire cable are the travelers: one on each brass screw, at both switches.
  3. Second switch: the black up to the light goes to the dark COMMON screw.
  4. Whites join straight through in each box; grounds pigtail to every green screw.

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 first 3-way switch goes to the breaker.
  • The white wire to the first 3-way switch goes to the neutral bar.
  • The bare copper wire to the first 3-way switch goes to the ground bar.

In the first switch box

  • The black wire from the panel goes to the COMMON lead.
  • The black wire to the second 3-way switch goes to one traveler lead.
  • The red wire to the second 3-way switch goes to the other traveler lead.
  • The white wire from the panel and the white wire to the second 3-way switch join under one wire nut.
  • The bare copper wire from the panel and the bare copper wire to the second 3-way switch join under one wire nut with a ground pigtail to the green lead.

In the second switch box

  • The black wire from the first 3-way switch goes to one brass traveler screw.
  • The red wire from the first 3-way switch goes to the other brass traveler screw.
  • The black wire to the light goes to the dark COMMON screw.
  • The white wire from the first 3-way switch and the white wire to the light join under one wire nut.
  • The bare copper wire from the first 3-way switch and the bare copper wire to the light join under one wire nut with a ground pigtail to the green ground screw.

In the light box

  • The black wire from the second 3-way switch goes to the fixture's black lead.
  • The white wire from the second 3-way switch goes to the fixture's white lead.
  • The bare copper wire from the second 3-way switch goes to the fixture's ground.

Parts for this box

As an Amazon Associate we earn from qualifying purchases.

Other boxes on this circuit