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How to Convert a Circuit to be Used for a Sub-Panel

By Dave Rongey - Summary:

Converting a 220 Volt Circuit Cable for a Sub-Panel: How to Install a Sub Panel Using an Existing Circuit, Sub Panels Require a 4-Wire Feeder Cable with a Separate Dedicated Neutral.

Converting a 220 Volt Circuit Cable for a Sub-Panel

Electrical Question: I have an old 220 volt circuit that went to an electric range.

  • We have since switched to N.G.
  • My question is can I reroute the 220 volt cable to the basement and use it for the power to a sub-panel?
  • I only have one receptacle in the basement.

Thanks for the info.

This electrical wiring question came from: Buck, from Emmett, Idaho.
See more about Home Wiring for Idaho

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

How to Install a Sub Panel Using an Existing Circuit

Application: Electrical Wiring for a Panel.
Skill Level: Intermediate to Advanced – Best performed by a licensed electrician.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the sub-panel.
Estimated Time: Depends on the type and size of the panel and available access to the project area.
Precaution: Any existing electrical wiring within the immediate area that may interfere with the installation of the sub panel should be identified and turned OFF and Tagged if necessary.
Notice: Installing additional electrical wiring and a sub-panel should be done according to local and national electrical codes with a permit and be inspected.

Sub Panels Require a 4-Wire Feeder Cable with a Separate Dedicated Neutral

  • 120/240 Volt Circuits
  • A typical sub panel that will be used to supply power for 120 volt circuits.
  • Typical 120 volt circuits may be receptacle outlets, lighting, smoke detectors, or any other 3-wire 120 volt device.

Circuit Disconnect for 240 Volt Equipment

  • 240 Volt Circuits
  • A Dedicated Neutral wire conductor is not required for 240 volt circuits for equipment that does not require a neutral.
  • Typical 240 volt equipment may be a hot water heater, air compressor, welder, or any 3-wire 240 volt equipment.
  • The circuit amperage requirements must be within the range of the amperage rating of the cable to be used for the circuit.

The total connected load of the circuits that would be added to a sub-panel must be 80% of the amperage rating of the cable supplying power to the sub-panel.

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2 Responses to “How to Convert a Circuit to be Used for a Sub-Panel”
  1. Chuck1963 says:

    We have a 220 volt dryer service that we are not using . I am setting up a wood shop in the same building ,can I split the 220 volt service in to a sub panel box & supply my wood working tools with 110 volts ?

    • Dave Rongey says:

      Hi Chuck,
      If the 220 volt dryer circuit is a 3-wire with a ground then yes you can use the circuit for a sub feed. The 3-wire circuit will have a separate insulated white neutral wire which is required for 120 volt circuits.
      If the 220 volt circuit does not have a separate neutral wire then no, you cannot use the circuit for a sub panel.


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