Modern electrical construction; a reliable, practical guide for the beginner in electrical construction, showing the latest approved methods of installing work of all kinds according to the safety rules of the National board of fire underwriters (1905)
Horstmann, Henry C[harles], 1858- [from old catalog], Tousley, Victor Hugo, 1875- [from old catalog] joint author · Chicago, F. J. Drake & Co. · leaf 192
between the points under all circumstances. They mustindicate whether the current be on or off. Knife Switches {See Figure 120.) Knife switches must be made to comply with the followingspecifications, except in those few cases where peculiar designallows the switch to fulfill the general… … c. Base.—Must be mounted on non-combustible, non-ab-sorptive, insulating bases, such as slate or por-celain. Bases with an area of over twenty-fivesquare inches must have at least four sup-porting screws. Holes for the supportingscrews must be so located or countersunk thatthere will be at least…
Electrical engineering
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
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