The majority of the circuits in your home are either 15-, 20-, or 30-amp circuits. But how much should you actually load each of these circuits to maintain a safe circuit load?
To determine this figure, you must implement ohms law. By simply multiplying the amperage times the voltage, you’ll get the total wattage capacity for the circuit. However, what we’re looking for here is the total safe amperage capacity to load the circuit.
So to determine this, we simply multiply the total wattage times 80%. To demonstrate what these figures look like, look over the chart below for these common circuit amperages used in homes. The figures are based on 120-volt circuits.