A pair of red wires, crossing over each other.

Wire Gauge

Originally contributed by • last updated 3/3/2021

Chris RubberDragon CC BY-SA 2.0
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Flickr

Other than plugging in a few devices and appliances around the home, most homeowners never really need to mess with the electrical wiring, unless there’s a problem. That’s probably a good thing because the thought of working with electricity can be frightening for some people. However, understanding a few basics about your home’s electrical system, such as wire gauge and why it’s important, can not only help you prevent damage to your devices and appliances, it may also prevent fires and save lives.

Definition

The term wire gauge refers to a number given to indicate the size (diameter) of an electrical wire. Gauge sizes are measured counterintuitively, with increasing gauge numbers equaling decreasing wire diameters and vice versa. The diameter of the wire typically determines the amount of electrical current that can flow through it and the amount of resistance it provides. Gauge sizes are fairly standardized under the American Wire Gauge (AWG) system (aka Brown and Sharpe), although other systems such as the Imperial (or British) Standard Wire Gauge (SWG) system are still sometimes used.

What Gauge Wire Do I Need?

If you’re in a position where you need to replace or repair the wiring in your home, you may want to consult an expert before attempting any big projects. Using the proper wire gauge size is incredibly important when rewiring or setting up a new electrical circuit in your home. If the diameter of the wire is too small to handle the amperage, the wire has the potential to overheat and even cause fires:

  • Typical residential wire diameters are designated as a 14 gauge or 12 gauge. However, appliances such as your electric stove, electric water heater, or central air unit may require a 10 gauge, 8 gauge, or even 6 gauge wire.
  • Understanding and selecting the proper gauge size is especially important when using household extension cords (typically 16 gauge). Before plugging in an appliance, such as a space heater, ensure the gauge size can handle the power needed to run the appliance.
  • If you’re looking to hook up speakers around the home, standard speaker wire is typically 16 gauge or 18 gauge. However, your wire choice may also be determined by the length of the wire and the intended sound quality.