The Basics of Circuit Electrical Load and the Different Wire Gauges

Having understood the basics of wiring and the various components of home circuits and wiring, it is important to ensure that all electrical appliances are matched to the right circuit electrical capacity. This is crucial especially when dealing with electrical appliances powered by a motor. Such appliances include dish washers, microwaves and sump pumps. Given the amount of power they need, these appliances require their own dedicated circuit. Such a circuit supplies the device with the right amount electricity while protection is offered against power surges by circuit breakers. Even with the breakers in place, they can only work if there is a predetermined size of the electrical load allowed to get through the current. So how does one calculate the right electrical load for a specific circuit?

From afar, it looks like a daunting task that should be left to specialists and geeks, but it is actually simple and interesting arithmetic. All you need to know is the voltage and amperage of the motor which will help you determine the wattage (electrical load) that can safely power the motor and hence the device. Knowing this helps you even in determining the right breaker you need for protection against excess electrical load. So let’s break down the whole thing. Any electrical motor comes with a rating on its side where information regarding its name, amperage, voltage serial number and type of current to be used is provided. Thus you can easily obtain the voltage and amperage of the motor with no effort or struggle.

Once you have the two numbers the next step is to multiply the two figures i.e. the amperage (AMPS) with the voltage (Volts). The resulting figure is the wattage of the device or the electrical capacity needed to power the device. Having known this you will need to set up a circuit that can match the load and still have a safe capacity. For example, take that your device has 120 volts and 15 amps. Its wattage is (15x120) = 1,800 watts. If you have a 20 amp circuit that still has 120 volts then the circuit has a total load or capacity of 2,400 watts. However, the safe capacity is arrived by multiplying the circuit wattage by 80% which gives 1,920 watts. Thus the safe capacity can meet the load required to power your motor without risk of fire or malfunctioning. The circuit breaker is thus set to allow only a maximum of 1,920 watts.

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Another factor that determines the circuit suitable for a device is the type of electrical wire gauge used. A wire gauge is the measurement of a wire by its diameter or cross-sectional area. It determines the amount of current a wire can safely carry, its resistance and weight per unit of length. The Americann wire gauging system has wires gauged from 1-20. The lower the gauge number, the bigger the size of the wire. The uses vary with lower numbers like three used for commercial and industrial purposes due to the heavy electrical load required. For domestic purposes gauge 12-20 are mostly used depending on the current.