This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
In the diagrams of lighting circuits in the following pages, the symbols given below will be used. See Fig. 14.
Symbol a is a safety plug, or cut-out.
Symbol b is a wall switch.
Symbol c is a 32-candlepower lamp.
Symbol d is a dynamo.
Symbol e is a 16-candlepower lamp.
Symbol f is a 16-candlepower lamp with a key socket
Symbol g is a 2-arm bracket with key sockets.
Symbol h is a 3-light chandelier with key sockets. Symbol i is a 10-candlepower lamp.