3-Way Switch Wiring - Routing Cable thru Ceiling Box and Between Switches

This article describes the wiring for a 3-way switch routing the cable thru a ceiling box and between switches.

The following items must be considered when wiring your 3-way switch

• At the ceiling box--the ungrounded conductors (a.k.a. hot) for the fixture connect to the black wire coming from switch 2. The white wire from the circuit power source cable is the grounded leg conductor (a.k.a. neutral) for the fixture. The black wire from the switch 1 connects to the black wire from the circuit power supply cable.
• Wrap a piece of black electrical tape around both ends of the white wire going between the 2 switch boxes as well as the portion of white on this cable being looped thru the fixture box, as this wire is also being used as an ungrounded conductor (a.k.a. hot).
• Bare wires are together and grounded to box (if metallic) and if the fixture has a green wire or a grounding screw, it gets grounded also. Bares and green wires are equipment grounding conductors.

If You Need Onward Power From the Fixture Then:

If Only Switched Power Required Onward Then at Existing Fixture:

• Onward cable--black/white/bare
• Connect black from onward cable to the black wire coming from switch 2
• Connect white from onward cable to white wire of the circuit power supply cable
• connect bare from onward cable to bare coming from circuit power supply cable and to electrical box if metallic
• At the onward cables destination, the black is the switched ungrounded conductor (a.k.a. hot), the white is the grounded leg (a.k.a. neutral), and the bare is the equipment grounding conductor

If Only Unswitched Power Required Onward Then at Existing Fixture:

• Onward cable--black/white/bare
• Connect black from onward cable to black wire coming from circuit power source cable
• Connect white from onward cable to white coming from circuit power supply cable
• Connect bare from onward cable to bare coming from circuit power source cable and to electrical box if metallic
• At the onward cables destination, the black is the ungrounded conductor (a.k.a. hot), the white is the grounded leg (a.k.a. neutral), and the bare is the equipment grounding conductor.

If switched and unswitched power required onward then at existing fixture:

• Onward cable--black/red//white/bare
• Connect black from onward cable to black wire coming from circuit power supply cable
• Connect red from onward cable to the black wire coming from switch 2
• Connect white from onward cable to white coming from circuit power supply cable
• Connect bare from onward cable to bare coming from circuit power source cable and to electrical box if metallic
• At the onward cables destination, the black is the unswitched ungrounded conductor (a.k.a. hot), red is the switched ungrounded conductor (a.k.a. hot), the white is the grounded leg (a.k.a. neutral), and the bare is the equipment grounding conductor

If You Need Onward Power From the Switch Then:
This is not possible with this configuration as no grounded leg (a.k.a. neutral) exists at the switch locations.

The common screw of a 3 way switch is the Odd color screw

If wiring multiple fixtures be sure to check the following guidelines concerning how to do it and what not to do: Wiring Multiple Fixtures.

If you are new at understanding the "politically correct" electrical terminology and need clarification of the terms used, we strongly urge you to read the Clarification of Definitions and Terminology guide. This will explain the terminology used in this article.