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How to Determine the Maximum Wattage per Outlet

If you need to determine the maximum wattage per outlet in your home, you can either divide the wattage across outlets, or run the maximum from a single outlet. Most outlets run off a circuit. A circuit runs from your main electrical box to an area of your home. Your house likely has many circuits. Big appliances like hot water heaters typically have their own circuit. Circuits in your living room or bedroom will have several outlets per circuit. The maximum wattage depends on circuit amperage. Once you know that, you can determine the wattage you can run from the outlet.

Things You'll Need

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Instructions

    • 1

      Check your electrical circuit breaker box for the amperage of your box. The circuits should be marked on the inside cover of the box. If it isn't, turn off the breaker to ensure it is for the circuit in question. Note the amperage of the circuit. The maximum amperage will be marked on the circuit breaker switch for that circuit.

    • 2

      Multiply the amperage by your home's voltage. Most homes run between 110 volts and 120 volts. To be conservative, use 110 volts. Therefore, if the circuit is 15 amperes, the wattage at which the breaker will switch is 1,650 watts.

    • 3

      Deduct 10 percent of the wattage for a buffer. At 1,650 watts, the result is 1,485. This means you can run 1,485 watts out of a single outlet on that circuit, provided you have no other power drawing on that circuit.

    • 4

      Divide the wattage by the number of outlets to find the average number of watts you can use per outlet. For a circuit with 1,485 watts, this comes to around 185 watts per outlet.