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4 Way Light Switch Wiring Diagram

Four-way switch diagram with LOAD in one 3-way switch box and LINE in the other 3-way switch box

Four-Way Switch Wiring Diagrams

Dear Mr. Electrician: How do I wire four way switches?  I need additional light switches to control the same light fixture from multiple locations.  Are there 4-way switch wiring diagrams available? Answer: Yes, 4-way wiring diagrams are below.  You can add as many 4-ways as you want as long as you have the LINE and LOAD correctly connected on the 3-way switches.  NOTE: Text links go to applicable products on Amazon.com 4-WAY SWITCH WIRING DIAGRAMS The schematic diagram below shows how all four way switches are wired.  The wiring diagram further down depicts another choice of wiring method. In some countries the four-way is called an intermediate switch.  You would just continue from one 3-way switch box with the 14/3 three conductor cable (Two colored traveler wires, a white neutral, and a bare or green ground wire) in and out of each four-way switch box.  The white wires get spliced through.  The red and black wires are connected to the four-way switches.  At the other end you connect the other 3-way switch with either the LINE or the LOAD.  See the light switch wiring diagrams above and below. Follow the switch manufacturer’s instructions and wiring diagram as the connections on the switch vary by manufacturer.  Sometimes the switch wiring connection diagram is printed on the inside of the 4-way switch packaging box (See example below). Bare or green ground wires are spliced together with a pigtail or two and then connected to the metal switch box with a 10/32 machine screw, and to the green screw on the switch. Due to the proliferation of WiFi smart switches and electronic dimmers the National Electrical Code now requires that a neutral conductor be installed in at least one of the switch boxes.  See Article 404.2(C).  This is easily accomplished by bringing the power feed into the switch box instead of the ceiling light.  It is not acceptable, and can be dangerous, to use the equipment grounding conductor as the neutral connection for a smart switch. At one time there were electronic switches and dimmers that were approved to connect the neutral of the switch to the grounding conductor.  That is no longer allowed.  There may be some smart switches for sale that do not require a neutral conductor to operate, but their functions may be limited. You must use electrical boxes for your light switches that are approved for the number of wires and devices that you will be installing.  See article 314 in the National Electrical Code (NFPA 70) to determine what size electrical boxes you should use. Keep in mind that each light switch will count as two wires when calculating your box fill.  In addition any clamps inside of the box will count as one wire.  Connectors that are outside the electrical box with only the locknut inside do not count as a wire. An update in the 2020 National Electrical Code requires that all ceiling light electrical boxes where a ceiling fan could possibly be installed must be rated for ceiling fan support.  See article 314.27(C). Below is another...