Electricity has become an essential part of contemporary life, energizing lights, appliances, heat, air conditioning, televisions, telephones, computers, and many other modern conveniences.

Electricity arrives at your house from your local utility company by a power line or underground though a conduit. Most homes have three-wire service—two hot wires and one neutral. Throughout the house, one hot wire and one neutral wire power conventional 120-volt lights and appliances; both hot wires and the neutral wire make a 240-volt circuit for large appliances such as air conditioners and electric furnaces. An electric meter, monitored by your electric utility company, is mounted where the electricity enters your house.