Utility companies distribute power to individual households through overhead wires or underground cables. Today, most homes have three-wire service. That is, the utility company connects three lines to the service entrance equipment. Whith this arrangement, there are two "hot" conductors (wires), each supplying electricity at 120 volts, and one "neutral" conductor. During normal operation, this neutral wire is maintained at zero volts, or what is referred to as "ground potential".
(三相电包括两根120伏的火线和一根地线)
Three-wire service provides both 120-volt and 240-volt capabilities. One hot conductor and the neutral conbine to provide for 120-volt needs, such as light fixtures or wall receptacles (outlets). Both hot conductors combine with the neutral to provide 120/240 volts for large appliances, such as a range (火炉) or clothes dryer.
(单根或限与地线组合,提供120V电压,用于轻量电器及插座;两根火线组合,提供240V电压,用于大功率电器,如火炉或干衣机。)
(三相电包括两根120伏的火线和一根地线)
Three-wire service provides both 120-volt and 240-volt capabilities. One hot conductor and the neutral conbine to provide for 120-volt needs, such as light fixtures or wall receptacles (outlets). Both hot conductors combine with the neutral to provide 120/240 volts for large appliances, such as a range (火炉) or clothes dryer.
(单根或限与地线组合,提供120V电压,用于轻量电器及插座;两根火线组合,提供240V电压,用于大功率电器,如火炉或干衣机。)