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The Carter system, also known as the Chicago system, was a method of wiring three-way switches in the era of early knob-and-tube wiring. This now-obsolete wiring method has been prohibited by the USA National Electrical Code since 1923, [2] even in new knob-and-tube installations which are still permitted under certain circumstances. This ...
Wiring systems in buildings may be subject to frequent alterations. Frequent wiring changes are made simpler and safer through the use of electrical conduit, as existing conductors can be withdrawn and new conductors installed, with little disruption along the path of the conduit. A conduit system can be made waterproof or submersible.
The conduit methods were known to be of better quality, but cost significantly more than K&T. [2] In 1909, flexible armored cable cost about twice as much as K&T, and conduit cost about three times the price of K&T. [6] Knob and tube wiring persisted since it allowed owners to wire a building for electricity at lower cost.
Cable trays are used as an alternative to open wiring or electrical conduit systems, and are commonly used for cable management in commercial and industrial construction. They are especially useful in situations where changes to a wiring system are anticipated, since new cables can be installed by laying them in the tray, instead of pulling ...
Flow rate may also be controlled by inlet vanes or outlet dampers on the fan. Some residential air handlers in USA (central "furnaces" or "air conditioners") use a brushless DC electric motor that has variable speed capabilities. [1] Air handlers in Europe and Australia and New Zealand now commonly use backward curve fans without scroll or ...
The first rubber-insulated cables for US building wiring were introduced in 1922 with US patent 1458803, Burley, Harry & Rooney, Henry, "Insulated electric wire", issued 1923-06-12, assigned to Boston Insulated Wire and Cable . These were two or more solid copper electrical wires with rubber insulation, plus woven cotton cloth over each ...