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    Do it Yourself - How to wire an Electrical Disconnect.


       Wiring Home > Electrical > Disconnects
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    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.


    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.

    Electrical Disconnects

    The National Electrical Code states that “A means shall be provided to disconnect each appliance from all ungrounded conductors”. What doses this mean for you when wiring your home?

    If the appliance or device you are wiring is more than 50 ft away from the electrical panel, or not within sight of the electrical panel, you must have a means of disconnecting the power. If you cannot see your electrical panel or if you can see it but it is more than 50 ft away you will need a disconnect.

    Acceptable Means of Disconnect

    1)   A plug is acceptable to use, this would cover appliances such as your stove, refrigerator, dryer etc. Do not direct wire these appliances, you need to have the plug as a means of disconnecting power.

    2)   A Thermostat with a clearly marked off position that directly opens all ungrounded conductors and cannot turn on when in the off position can be used as a means of disconnect for electric baseboard heating.

    3)   Your hot water heater, furnace, well pump or central air conditioning unit all require an electrical disconnect if you cannot see your electrical panel from the location or if you can see it but it is more than 50 ft away. The hot water heater and furnace may or may not need one, while the central air unit and the well pump will always need one.

    The disconnect will need to be in sight of the appliance or motor, it will need to have the ability to fully disconnect the hot conductors from the unit. It also needs to be capable of being locked out.

    Make sure you use the proper size disconnect!

    Example: If the current draw is 28 amps, you will need a disconnect rated for 30 amps. If the current draw is 48 amps, you will need a disconnect rated for 60 amps.

    How to wire a disconnect

    The Line side is the cable supplying voltage from your electrical panel.

    The Load side is the side that is connected to what you are supplying power to.

    The grounds connect to a lug that is screwed to the disconnect enclosure. If there is not already one pre-installed you will need to install one by screwing it to the enclosure. It doses not matter where it is placed.

    If a neutral conductor is required you will need to install an isolated neutral bar and make the connection there, or purchase a disconnect that has an isolated neutral bar already installed.

    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.

    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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    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.