|
Aluminum wiring is a type of wiring used in houses, power grids, and airplanes. Aluminum provides a better conductivity to weight ratio than copper, and therefore is used in power wiring of some aircraft.〔Telecommunications and networks, Khateeb M. Hussain, Donna Hussain〕〔(Aircraft Wire ). mechanicsupport.com〕 Utility companies have used aluminum wire for electrical transmission in power grids since the early 1900s. It has cost and weight advantages over copper wires. Aluminum wire in transmission and distribution applications is still the preferred material today. In North American residential construction, aluminum wire was used to wire entire houses for a short time from the late 1960s to the late 1970s during a period of high copper prices. Wiring devices (outlets, switches, fans, etc.) at the time were not designed with the particular properties of aluminum wire in mind and there were problems with the properties of the wire itself. Older wiring devices not originally rated for aluminum wiring present a fire hazard. Revised manufacturing standards for wiring devices were required. ==Increased copper prices== In the mid-1960s when the price of copper spiked, aluminum wire was manufactured in sizes small enough to use in homes. Aluminum wire requires a larger wire gauge than copper to carry the same current. When first used in branch circuit wiring, aluminum wire was installed the same way as copper. Typical connections from electrical wire to electrical devices, also called terminals, are usually made by wrapping the wire around screw terminals and tightening the screw. Over time, many of these terminations to aluminum wire began to fail due to improper connection techniques and dissimilar metals having different resistances and different coefficients of thermal expansion. These connection failures generated heat under electrical load and caused overheated connections. In the late 1960s, a device specification known as CU/AL was created that specified standards for devices intended for use with aluminum wire. Because of more rigorous testing, larger undercut screw terminals were designed to hold the wire more suitably. Unfortunately, CU/AL switches and receptacles failed to work well enough with aluminum wire, and a new specification called CO/ALR (meaning copper-aluminum, revised) was created. These devices employ screw terminals that have even deeper undercuts and are designed to act as a similar metal to aluminum and to expand at a similar rate. CO/ALR applies only to standard light switches and receptacles; CU/AL is the standard marking for circuit breakers and larger equipment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Aluminum wire」の詳細全文を読む スポンサード リンク
|