. American telephone practice . 733. yz sleeveFIG. WITH McINTYRE SLEEVE. shown in Fig. 578, and pulling it up with a block-and-tackle or byhand. The tension depends on the kind and size of wire, on thedistance between the poles, and on the temperature at time of thestringing. The amount of tension put on each wire is usually takenas about one-third the breaking strength of the wire, which may befound from the wire tables. The other method is to allow a cer- 800 AMERICAN TELEPHONE PRACTICE. tain sag or distance between the center of the span and the straightline between the poi
. American telephone practice . 733. yz sleeveFIG. WITH McINTYRE SLEEVE. shown in Fig. 578, and pulling it up with a block-and-tackle or byhand. The tension depends on the kind and size of wire, on thedistance between the poles, and on the temperature at time of thestringing. The amount of tension put on each wire is usually takenas about one-third the breaking strength of the wire, which may befound from the wire tables. The other method is to allow a cer- 800 AMERICAN TELEPHONE PRACTICE. tain sag or distance between the center of the span and the straightline between the points of support. Table XIII., which is taken from Roeblings handbook onWire in Electrical Construction, gives the sag in inches for thevarious lengths of span at different temperatures, these figures beingbased on the use of good hard-drawn copper wire. TABLE XIII —Amount of Sag in Spans. Spans in Feet. Temperature in Degrees Fahrenheit. 75 IOO 115 I30 150 2GO Sag in Inches. —30 I 2 2/2 3H 4^ 8 — IO I* 2^ 3 3U 5 9 lO I# 2/s 3lA
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