International Library of Technology · Scranton, International Textbook Co. · leaf 119
f wires use 40 poles to themile, while for exceptionally heavy lines, the use of 52 polesto the mile, or one pole every hundred feet, is not uncommonpractice. As a general rule, which it is safe to follow inthe majority of cases 35 or 40 poles to the mile should beused. For city work, the poles… … Fig. 1. white pine. Cross-arms are made in standard sizes, thelength of the arm depending on the number of pinsit is intended to hold. The standard cross-arm is3i X 4£ inches, and varies in length usually from 3 to8 feet. They are usually bored for l^--inch pins andprovided with holes for two…
Electrical engineering
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