If the system of wiring be such that auxiliary power is taken from a local lighting company, it is a good plan to have each circuit controlled by a double throw switch so that in case of overload any circuit can be fed from the illuminating company's mains as in fig.
— from Hawkins Electrical Guide v. 04 (of 10) Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications by N. (Nehemiah) Hawkins
|
|