Final answer:
The most common electrical service voltage for homes in the U.S. is 120 volts. Power companies transmit electricity at higher voltages and use transformers to step down the voltage for residential use, reducing energy loss during transmission.
Step-by-step explanation:
The most common electrical service for a house in the United States is typically 120 volts (V). Appliances in households are usually rated at 110 V, but power companies deliver electricity at higher voltages in the kilovolt range and then step it down using transformers to the standard voltages used in homes. This is done because transmitting electricity at higher voltage is more efficient for long distances, as it reduces the loss of power due to resistance in the wires, which is manifested as heat.
Houses in the U.S. are often equipped with circuit protection rated to 100 or 200 Amps to prevent overloads. When using household voltage of 120 V, we can calculate the power consumption using the formula P = IV (Power = Current × Voltage). For example, with a 100 A circuit operating at 80% capacity, the power consumption would be 96 kilowatts (kW). Over a month, this equates to a significant amount of kilowatt-hours (kWh), which would appear on the electricity bill, and is the unit for energy consumption that households pay for.