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    Do it Yourself - How to wire a three way switch.

       Wiring Home > Electrical > Switches and lighting > Three-way switching
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    This do it yourself section covers a basic three-way switch. A three-way is used when a light or group of lights, or other load, must be controlled from two different switching points.

    A three-way switch has one terminal, called the common terminal, to which the switch blade is always connected. In addition there are two other terminals. These are called the traveler wire terminals. In one position, the switch blade is connected between the common terminal and one of the travler terminals.

    In the other position connection is made between the common terminal and the other traveler terminal. Remember that a three-way switch is actually a single-pole, double throw switch. The three-way switch has no ON or OFF position, which is why there are no ON or OFF markings on the handle of the switch.

    Electric Shock Caution: To prevent severe shock or electrocution always turn the power OFF at the service panel before working with wiring.

    Never Assume the power is off! Always double check, and test the device before you begin work.

    If you are replacing a switch make sure to mark which terminals the wires are on before you disconnect them.

    three way electrical switching

    three wayTypically a 14/2 or a 12/2 cable is used as a feed, a 14/3 or a 12/3 is ran in between the switches. Than a 14/2 or 12/2 is ran to the lighting fixture. The use of either 14g or 12g cable is determined by the current load of the lighting fixtures you are controlling.

    If you are having problems, Play it Safe.
    Make sure you check the regulations in the National Electrical Code regarding the device you are wiring. If you are still unsure of how to properly wire the circuit you are working on, you will need to contact a qualified electrician in your area. You can also ask questions in our forum.

    1) Make sure all devices and splices are in a UL listed electrical box of the proper size.

    2) Make sure you attach the ground wire to all metal boxes and all devices, with the proper ground screw.

    3) Twist wires together with pliers, before you put the wire nut on. Double check to insure that the connection is tight, and that no copper is showing.

    4) Always use the screws for termination of wires. Never use the holes in the back of a device for the connection.

    5) Switches have differant ratings, some switches may be rated for 15amps at 125 volts, while others will have higher voltage and ampere rating. Make sure you use the switch that is rated for the voltage and amperes you are using. Never exceed 80% of the ampere rating of a switch.

    6) A switch in a wet location or outside of a building shall be enclosed in a UL listed weatherproof enclosure or cabinet. Switches shall not be installed whithin wet locations in a tub or shower spaces, unless installed as part of a listed tub or shower assembly.

    Related Sections: Single Pole Switches > Four Way Switches > Dimmer Switches

    Related Resources:

  • National Electrical Code Handbook
  • National Electrical Codebook
  • Stallcup's Illustrated Code Changes
  • The Complete Guide to Home Wiring (Black and Decker Complete Guides Series)
  • Wiring Simplified
  • Guide to Using the National Electrical Code
  • Residential Remodeling and Repair Professional Reference

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    Back to the Top > Wiring Home > Electrical > Switches and lighting > Three-way switching

    It is important to note that electrical codes change, and that in some areas local electrical codes are not the same as the National Electrical code. The local authority having jurisdiction in your area may have different codes than the national code. It is important to find out if your local codes differ from the national code, your local authority having jurisdiction is the final judge and jury.

    Disclaimer: You understand that you are personally responsible for your own wiring, and that you're wiring should conform to the National Electrical code. The information provided is general installation advice. We make no claims about the completeness or the accuracy of the information as it may apply to an infinite amount of field conditions. It is the responsibility of the person or persons using this information to check with all concerned parties, owners and local authorities, etc. before doing an installation. Users of this information agree to hold Wireityourself.com or any of its agents harmless form liabilities of any kind relating to the use of this information. You also agree to the terms set forth in our terms and conditions.