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In building wiring, multiway switching is the interconnection of two or more electrical switches to control an electrical load from more than one location.A common application is in lighting, where it allows the control of lamps from multiple locations, for example in a hallway, stairwell, or large room.
Double switching, double cutting, or double breaking is the practice of using a multipole switch to close or open both the positive and negative sides of a DC electrical circuit, or both the hot and neutral sides of an AC circuit. This technique is used to prevent shock hazard in electric devices connected with unpolarised AC power plugs and ...
Telegraph pole with spars, insulators and open wires on a now decommissioned Railway Pole Route, Eccles Road, Norfolk, United Kingdom. A pole route (or pole line in the US) is a telephone link or electrical power line between two or more locations by way of multiple uninsulated wires suspended between wooden utility poles. This method of link ...
NEMA 1-15P (two-pole, no ground) and NEMA 5-15P (two-pole with ground pin) plugs are used on common domestic electrical equipment, and NEMA 5-15R is the standard 15-ampere electric receptacle (outlet) found in the United States, and under relevant national standards, in Canada (CSA C22.2 No. 42 [1]), Mexico (NMX-J-163-ANCE) and Japan (JIS C 8303).
A disadvantage of double circuit transmission lines is that maintenance can be difficult, as either work in close proximity of high voltage or switch-off of two circuits is required. In case of failure, both systems can be affected. The largest double-circuit transmission line is the Kita-Iwaki Powerline.
Compared to modern electrical wiring standards, these are the main technical shortcomings of knob-and-tube wiring methods: never included a safety grounding conductor did not confine switching to the hot conductor (the so-called Carter system prohibited as of 1923 places electrical loads across the common terminals of a three-way switch pair)
SPST-NC (Single-Pole Single-Throw, Normally-Closed) relays have a single Form B or break contact. As with an SPST-NO relay, such a relay has four terminals in total. SPDT (Single-Pole Double-Throw) relays have a single set of Form C, break before make or transfer contacts. That is, a common terminal connects to either of two others, never ...
Electrical panels, cables and firestops in an electrical service room at a paper mill in Ontario, Canada. Electrical panels are easily accessible junction boxes used to reroute and switch electrical services. The term is often used to refer to circuit breaker panels or fuseboxes. Local codes can specify physical clearance around the panels.