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240 Volt Outlets

What is a 240 volt outlet?

Standard electrical outlets contain two 120 volt wires and one neutral wire that deliver power to items in your home using one phase of your electrical service. The 240 volt receptacles work differently. They use both 120 volt wires, a neutral wire, and in newer homes, a ground wire, to power a single receptacle. (Older homes and appliances may use three prong 240v outlets.) Many large, motor-driven appliances run more efficiently with a 240 volt power supply. The 240 volt outlets are intended for use specifically with this equipment, which host a 240 compatible plug.

Which appliances use 240 volt outlets?

Many large appliances require 240 volt outlets. You may need to install a 240 volt outlet if you purchase one of the following items:

  • Ovens, ranges, and cooktops
  • Clothes dryers
  • Water heaters
  • Furnaces
  • Air conditioners
  • Garage power tools
  • And more recently, electric cars

Identifying 240 Volt Outlets

Compared to smaller, standard receptacles, 240 volt outlets are larger, with rounded tops, and three or four holes depending on the age of the outlet. Three prong outlets have a hole like a backward “L” on top and two diagonal holes on the sides. Four prong outlets have an “L” on top, two vertical side holes, and a single, half circle hole on the bottom

Why do some 240 outlets have three prongs, while others have four?

Recently, 240 volt outlets have switched from three prong to four prong. Older, three prong outlets were designed to contain two live wires and one neutral. The additional prong on four prong outlets adds a ground, providing additional safety against electrical shock. Rewiring your appliance with a new, four wire cord (and four prong plug) will solve any compatibility issues.

If you find yourself scratching your head when it comes to solving electrical issues in your home, contact Mr. Electric®. We have the knowledge and tools to get you on the right track.