How To Look At A House

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How can I change a 240V circuit to a 120V circuit?

Friday, July 13, 2018

We usually get asked this question by someone who is switching from an electric range to gas. They need a 120V outlet behind the new gas range where the now-useless 240V electric range outlet is, to power the control panel and igniters for the burners, and want to recycle one leg of the existing breaker and the wiring. Unfortunately, that’s an unsafe solution. The reason is that 120V outlets are rated for either 15 or 20-amps of maximum current flow, and the appliances plugged into them are likewise rated for no more than that. The 50-amp breaker in the panel for the electric range will not trip until the current flow is more than twice the rating of the receptacle and appliance that is plugged into it, and that’s a recipe for overheated wires and a house fire. 

    Here’s a couple of possible solutions to this problem:

  1. Replace the 240V breaker with a 120V breaker, with the 15 or 20-amp rating that is correct for the new outlet.  The oversize wiring running from the panel is not a problem. A pigtail at each end to bring it down to a #14 (15-amp) or #12 (20-amp) copper wire works fine. Also, install a  snap-in cover plate over the opening in the deadfront left by the reduction to the smaller 120V breaker. 
  2. If you need multiple 120V circuits, then install a subpanel where the former 240V electric range, dryer, or water heater was located, with a rating matched to the breaker in the main panel. This can potentially give you plenty of circuits. 

    We recommend that a electrician do the circuit change-out for you. Although it seems like a simple task, making snug wire connections and installing and protecting the components to NEC safety standards is best left to a professional.

    Also, see our blog posts Can you add circuit breakers by different manufacturers to an electric panel if they fit? and What is the maximum number of circuit breakers allowed in an electric panel?

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 

Here’s links to a collection of our other blog posts about ELECTRIC PANELS:

What causes copper wires to turn green or black in an electric panel?  

When should a corroded or damaged electric panel cabinet or disconnect box be replaced? 

What is a tandem circuit breaker? 

When did arc fault circuit interrupter (AFCI) breakers first become required?

Can an electric panel be located in a closet? 

Can an electric panel be located in a bathroom? 

My circuit breaker won't reset. What's wrong?  

What is a split bus electric panel?

How do I identify a combination AFCI (CAFCI) circuit breaker? 

What does a circuit breaker with a yellow or white test button indicate? 

What is the maximum gap allowed between the front of a recessed electric panel box and the wall surface surrounding it? 

What are the requirements for NM-cables entering an electric panel box?

Why is a fuse box/panel an insurance problem for homebuyers? 

Why is bundled wiring in an electric panel a defect?

What is a Dual Function Circuit Interrupter (DFCI)? 

What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

What is the difference between "grounded" and "grounding" electrical conductors? 

What is the right electric wire size for a circuit breaker in an electric panel?

What is the life expectancy of a circuit breaker? 

My circuit breaker won't reset. What's wrong? 

Why do some breakers in my electric panel have a "TEST" button on them?

What is the right size electric panel for a house? 

    Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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