What to do with Unused Electrical Circuit Wiring

By Dave Rongey - Summary:

How do I disconnect the electrical wires and leave them in the panel for future use? Disconnecting Unused Electrical Wires, How to Keep Spare Electrical Wiring Safe for Future Use.

Safe Keeping for Unused Electrical Wires

Electrical Question: How do I disconnect the electrical wires and leave them in the panel for future use?

  • I installed a gas furnace and want to use the old furnace circuit.
  • How do I correctly disconnect the electrical wire to the furnace to leave it in the panel for future use?

This home electrical question came from: Corine, a Homeowner from Auburn, Washington.

Dave’s Reply:
Thanks for your electric wiring question Corine.

Disconnecting Unused Electrical Wires


Application: Disconnecting Electrical Circuit Wiring.
Skill Level: Advanced – Best performed by a Licensed Electrical Contractor or Certified Electrician.
Tools Required: Electricians Pouch of Hand Tools for Rough-In Wiring, Electric Drill and Auger Bits and Extension Cord.
Estimated Time: Depends on the extent of the project, the type of construction and available access to the project area.
Precaution: The existing furnace circuit should be identified and turned OFF and Tagged.
Notice: Installing additional electrical wiring should be done according to local and national electrical codes with a permit and be inspected.

How to Keep Electrical Wiring Safe for Future Use

The process of disconnecting and safe keeping of unused electrical wires to be available for future use.

  • Identify the old furnace circuit at the electrical panel.
  • Turn the circuit breaker into the OFF position.
  • At the old furnace location, the circuit wiring should be completely disconnected and removed from the old furnace.
  • Install the circuit cable into a junction box where each insulated wire is capped off using wire nuts or insulated wire connectors, then place a blank cover over the junction box.
  • A surface mounted junction box is typically installed for this procedure when the box is sized appropriately for the size of the circuit wires.
  • The exact type of junction box will depend on the location and available access to the circuit cable.
  • The junction box should have a clamp or fastener for the cable, and the cable should be secured using a cable strap or staple where the cable is exposed before entering the junction box.
  • The circuit breaker should now be relabeled as the old furnace circuit and that it is unused or spare.

Electrical panels have exposed wiring and components that are energized with electricity. It is not recommended that homeowners perform work in electrical panels but rather contact a qualified electrician who has experience working in home electrical panels.

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  • This article looks at common 120 volt and 240 volt house wiring circuits and the circuit breakers that are installed identifying the types and amperage sizes used in most homes.

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  • The size of the home electrical service panel is designed by calculating the square footage of the home and factoring in the code requirements for the electrical circuits that are required.

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Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all projects.


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FAQs Frequently Asked Questions and Comments

2 Responses to “What to do with Unused Electrical Circuit Wiring”
  1. Dave Rongey says:

    Hi Jason,
    NEC Article 406.8 mentions the requirement for metal while-in-use covers for receptacles in damp or wet locations.

    I hope this helps,

  2. Jason says:

    Where in the code does it say I have to use industrial inuse covers?


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