POLE-LINE CONSTRUCTION 49 



The tops of the poles and the places where the brackets and braces are to be 

 attached should also be treated with two coats of hot creosote, and the same is true of 

 the butts of braces and the slanting top which is to rest against the pole. 



A convenient outfit for brush treatment consists of a 5-gal. or 10-gal. can or iron 

 pot, a 3-gal. pail, i-gal. dipper, a 4-in. or 5-in. wire-bound brush, and a thermometer. 

 A small-sized, galvanized-iron wash-tub has been used with success in some places as 

 a vessel in which to heat creosote oil. 



Section 54 Length of Poles 



The standard pole is 22 ft. long, and this dimension will be used in all but special 

 cases. When for any reason non-durable poles must 'be used without preservative treat- 

 ment, the standard length will be 25 ft. and no shorter poles may be used without 

 specific authority from the district inspector. 



Poles shorter than 22^ ft. may be used, with the approval of the district inspector, 

 provided the standard length is not available, or, for some reason, is undesirable. 

 When a line crosses solid rock, and when it would be cheaper, the use of 2-in. or 2^-in. 

 wrought-iron pipes for short-length poles should be considered, notwithstanding their 

 liability to rust. Such poles may be fitted into drilled holes, thereby making blasting 

 unnecessary. There are several forms of commercial brackets and pins which, by the 

 use of a little ingenuity, may be set into the top of these poles or fastened to the side 

 by carriage bolts. 



Poles longer than 22 ft. may be used: 



(1) Where the spacing of the poles is such that the required sag in the line would 

 bring the wire too close to the ground. 



(2) Where the underbrush exceeds 10 ft. in height. Use poles that will keep the 

 lowest wire at least 4 ft. above the highest brush at the middle of the span. 



(3) Where snow is likely to drift to depths exceeding 10 ft. use poles that will 

 keep the lowest wire at least 2 ft. above the maximum height of the drift at the middle 

 of the span. 



(4) Where it is necessary to grade the line to overcome abrupt changes in level. 

 For example there should not be an abrupt change from a 22|-ft. pple to a 45-ft. pole. 

 Instead after a 22^-ft. pole place a 30-ft. pole and then complete the change by using 

 poles of gradually increasing length until the 45-ft. length is reached. 



(5) Where the line crosses wagon roads or railways. Use poles that will allow a 

 clearance between the lowest wire and the road-bed of at least 16 ft. above a road and 

 25 ft. above a railway, measured from the middle or highest point of the road or track. 

 Greater heights must be maintained if required by provincial laws. (See "Cross- 

 ings," Section 66.) 



(6) Where necessary to cross over instead of under other poles. (See "Cross- 

 ings," Section 66.) 



(7) At the ends of long spans (more than 500 ft.) across rivers and canyons. 

 Special poles or construction, approved by the district inspector, should be used. 



Poles shorter than 22 ft. may be used: 



(1) On short lines where the standard length pole cannot be readily secured. 



(2) When stubs of durable species or treated with creosote are employed. 

 Before using short poles the approval of the district inspector must be secured. 



No pole less than 18 ft. long or 5 in. in diameter at the top may be employed. 



Section 55 Erection of Poles 

 1 DISTRIBUTION OF POLES 



In distributing poles along a line the heaviest ones should be selected for use on 

 curves, at corners, at the ends of long spans, and at terminals. 

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