Final answer:
To calculate the minimum amperage for a dwelling unit, tally the wattage of all appliances at maximum capacity, use the formula P = IV, divide the total wattage by the voltage to find the total current, and ensure the circuit amperage can handle this demand. An example calculation shows a home using 11.52 kW at 80% capacity on a 100 A circuit would result in a monthly cost of $1,244.16 at $0.15 per kWh.
Step-by-step explanation:
To calculate the minimum amperage for a dwelling unit, you would need to assess the combined wattage of all the appliances and electrical devices in the unit when they operate at their maximum capacity. Each device has a power rating in watts, and this rating is higher for appliances such as a toaster because they use more energy to generate heat compared to a digital clock. The power (in watts) of an appliance can be calculated using the formula P = IV, where P is the power, I is the current in amperes, and V is the voltage in volts. Once you have the total wattage, divide it by the household voltage (usually 120 V in the US) to get the total current in amperes. This will give you an idea of the minimum circuit amperage required for the dwelling unit.
For example, if a home operates at 80% of a 100 A circuit at 120 V, it is using 96 A. Multiply this current by the voltage to find the power consumption: 96 A x 120 V = 11,520 W or 11.52 kW. To find the monthly consumption, multiply 11.52 kW by the number of hours in a month (assuming 30 days in a month, so approximately 720 hours), resulting in an estimated consumption of 8,294.4 kWh per month. At $0.15 per kWh, the monthly cost would be approximately $1,244.16.