The disorder results from overproduction of collagen, a naturally occurring protein found in the skin. It is unknown what causes this overproduction of collagen to occur but the immune system is believed to play a significant role. Morphea is not contagious or passed down in families.
A typical US household voltage is 120/240 V, 60 hz, single phase. There is a tolerance and the actual measured voltage is rarely exactly 120 volts. A common reading at my house is 117 volts. Industrial motors are made and rated in multiples of 115V (115, 230, 460, and 550Vac) for use on line voltages in multiples of 120 V (120, 240, 480, and 600 Vac).
Georgia State University's website offers a schematic illustrating both 240-volt and 120-volt household electrical wiring. The standard wiring design in the U.S. is two 120-volt hot wires and a neutral ground wire with a total maximum available voltage of 240.