How to Ground a Portable Generator and Make a Power Box

By - Summary:

How do I make an extension cord to extend the power from my generator out to a work area? How to Extend the Power of a Portable Generator.

Making a Receptacle Power Source from a Portable Generator

Electrical Question: How do I make an extension cord to extend the power from my generator out to a work area?

  • I have a 3 wire 240Volt outlet from a portable generator.
  • I am making and extension cord to extend the 240Volt out to the work area.
  • Can I also make a 120Volt outlet from this wiring configuration?
  • Grounding the Portable Generator
    Note that the generator is on a truck and ground strapped to the frame of the truck.

This electrical wiring question came from Chuck, in Phoenix, Arizona.

Dave’s Reply:
Thanks for your electrical wiring question Chuck.

How to Extend the Power of a Portable Generator


Wiring Configurations for Portable Generators

  • 3Wire Generator Plug
    The generator that has been described has a 3-wire outlet, which does not have a separate neutral, so you could not create a 120 volt outlet.
  • 4Wire Generator Plug
    If there were a 4-wire outlet then there would be the potential for 120/240 volts.
  • 120 Volt Portable Power From a 4Wire Outlet of a Portable Power
    From a 4wire outlet, the appropriate generator cord sized for the potential amperage rating of the outlet could be connected to a NEMA 3R panel which could provide the needed 120 volt circuits with would be provided through the appropriate over current protection or circuit breaker.

    • IMPORTANT: Outdoor electrical outlets should always have GFCI protection.
  • Connecting a Portable Generator to a Home Panel
    Connecting a portable generator to a home must always be done through an approved transfer switch or circuit interlock device to ensure power separation between the electric utility company and the portable generator.

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  • Portable Home Generators
    • Portable electric generators for home use and the proper electrical connection to your home.

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