Electrical Systems
 
Electrical Systems
Electricity has become an essential part of contemporary life, energizing lights, heat, air conditioning, cooking appliances, 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¡ªtwo 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 an air conditioner or an electric furnace. Generally, 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. A circuit consists of a hot (usually black) wire that goes from the main panel to a series of lights, receptacles, or appliances, and a neutral (usually white) wire that returns to the main panel. In addition to the neutral wire, a grounding wire also returns to the main panel and, from there, to the earth. The purpose of the ground is to divert electricity from any short-circuiting hot wires into the earth, preventing electric shock.

Subpanels 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 or laundry room. They also are equipped with a secondary set of circuit breakers.

Low-voltage electrical systems are also common in houses for powering doorbells, intercoms, sprinkler timers, outdoor lighting, and some types of low-voltage indoor lighting. Relative to conventional voltage wiring, these systems are much safer for homeowners to work on.

Shutting Off the Power
Making electrical repairs? If you need to shut off the power to the entire house,
here's how.
Push the main breaker handle to the OFF position
OR
Flip the main lever switch at the main panel to OFF
OR
Pull out the fuse block