Electrical wiring in the United Kingdom lawnmower does it need an RCD?" The risk of electrical shock on construction sites can be reduced by several measures, including reduction of the normal 230 volt distribution voltage to 110 volts for electrical lighting and power tools. By using a centre-tapped transformer, each conductor of the circuit is only at 55 volts with respect to earth. This reduces the chance of dangerous electrical shock when using power tools in wet locations. Where 230 volts must be used, a residual current device (RCD) can be used to detect small leakage currents and automatically isolate faulty equipment. In sites where hazardous
Manganin Manganin Manganin is a trademarked name for an alloy of typically 84% copper, 12% manganese, and 4% nickel. It was first developed by Edward Weston in 1892, improving upon his Constantan (1887). Manganin foil and wire is used in the manufacture of resistors, particularly ammeter shunts, because of its virtually zero temperature coefficient of resistance value and long term stability. Several Manganin resistors served as the legal standard for the ohm in the United States from 1901 to 1990. Manganin wire is also used as an electrical conductor in cryogenic systems, minimizing heat transfer between points which need electrical connections.