In the United States and Canada, the power grid is a split-phase system that supplies power to your house at a high voltage. That voltage is divided in half before it’s routed throughout your home. Most people know about and use 110, 115, 120, or 125 volts interchangeably to describe the power that comes out of a standard wall socket. Similarly, 220, 230, 240, and 250 volts are used to describe the higher voltage range that is used to supply power to larger appliances. But what are there all these different terms, and how should they be used?
The designations “110 volt” and “220 volt” represent an older, out of date standard that’s no longer found in new equipment. However, this standard is still familiar to many people, so it remains in use.
The terms “115 volt” and “230 volt” come from product design standards. Electrical devices are usually designed to operate in this range, plus or minus 10 percent.
The power delivered to your home is 120 or 240 volts. This is called “nominal voltage.” That means it’s the standard voltage as measured at the transformer outside your home. Nominal voltage can vary up to plus or minus 5 percent from its stated definition.
The outlets, plugs, and switches in your home can handle higher levels of power. They can take up to 125 or 250 volts. That’s the upper end of the voltage range for both the power grid and the typical wall socket in your home.
If you’re worried about getting the right voltage for your appliances, you don’t have to. Electrical equipment can accept variations of 10 percent, but the utility company will only vary by 5 percent in the voltage they deliver. You’ll find that the levels match up fairly well.