Home electrical system explained
Electricity arrives at your house from your local utility company by a power line or underground though a conduit. An electric meter, monitored by your electric utility company, is mounted where the electricity enters your house.

The main panel is usually right next to or under the meter. This is the central distribution point for the electrical circuits that run to lights, receptacles, and appliances throughout the house.

Sub-panels in other locations of the house, connected to the main panel, provide power to areas that have a number of different circuits or large appliances, such as the kitchen and laundry room. They also are equipped with a secondary set of circuit breakers.
Three-wire service—two hot wires and.
120V home appliances: One hot wire and one neutral wire power conventional 120-volt lights and appliances
240V home appliances: Both hot wires and the neutral wire make a 240-volt circuit for large appliances such as air conditioners and electric furnaces.
Low-voltage electrical systems: doorbells, intercoms, sprinkler timers, outdoor lighting, and some types of low-voltage indoor lighting.