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What Size Electrical Wire Do I Need?

Wire Gauge and Ampacity

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tangled electrical wires Peter Dazeley/Photographer's Choice RF/Getty Images An image of electrical wire lettering.

Electrical Wire Lettering

Peter Dazeley/Photographer's Choice RF/Getty Images

In order to install any electrical wire installation, the proper wire size for the application is needed. But how do you know what size wire to use? Wire is sized by the American Wire Gauge (AWG) system. Your installation of conductors will depend on a few factors. The gauge of the wire, wire capacity, and what the wire will feed should all be considered.

You’ll notice that the smaller the wire gauge, the larger the ampacity that the wire can handle. Wire ampacity is the safe amount of current that a wire can handle without getting hot or causing a fire. The following examples of devices in your home, the ampacity that they are rated for, and the wire gauge, will help you determine the right size wire for the appropriate application.

Wire Gauges and Uses

Wire Use Rated Ampacity Wire Gauge
Low-voltage Lighting and Lamp Cords 10 Amps 18 Gauge
Extension Cords 13 Amps 16 Gauge
Light Fixtures, Lamps, Lighting Runs 15 Amps 14 Gauge
Receptacles, 110-volt Air Conditioners, Sump Pumps, Kitchen Appliances 20 Amps 12 Gauge
Electric Clothes Dryers, 220-volt Window Air Conditioners, Built-in Ovens, Electric Water Heaters 30 Amps 10 Gauge
Cook Tops 45 Amps 8 Gauge
Electric Furnaces, Large Electric Heaters 60 Amps 6 Gauge
Electric Furnaces, Large Electric Water Heaters, Sub Panels 80 Amps 4 Gauge
Service Panels, Sub Panels 100 Amps 2 Gauge
Service Entrance 150 Amps 1/0 Gauge
Service Entrance 200 Amps 2/0 Gauge
Related Video
Guide to Wire Sizes

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