Henry and Hora's modern electricity; a practical working encyclopedia (1915)
Henry, James. [from old catalog], Hora, Karel Jan, 1881- [from old catalog] joint author · Chicago, Laird & Lee, inc. · leaf 218
the trough, at intervals of 2 feet, wooden supports(bridges) are placed, treated with bitumen and provided withslots into which the cables are laid, so as not to touch each other or the iron,The trough is then filledup with bitumen, andcovered with an inch ofconcrete or an iron lid.This system… … Fig. 90. 216 MODERN ELECTRICITY bituminous insulating material. These pipes are laid about30 inches deep, and about 20 inches from the curb They are jointed by means of couplingboxes, (see fig. 90,) cast iron shellsmade in halves. The bottom half isclamped over collars at the tube ends,then the…
Electrical engineering
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