The standard electrical dictionary : a popular encyclopaedia of words and terms used in the practice of electrical engineering (1898)
Sloane, T. O'Conor (Thomas O'Conor), 1851-1940 · London : Crosby Lockwood and Son · leaf 630
by buttons, and intended to befastened to the end of a flexible cord. Switch,Throw=Over. A doublethrow knife switchdesigned to con-nect a three wire system in a build-ing either to a three wire streetmain or to a single source on thetwo wire system. The wiring forthis usage must have the… … Fig. 387. Voltmeter Switch.
Electricity
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