60 METHODS OF COMMUNICATION FOR FOREST PROTECTION 



All iron wire should be well galvanized to protect it from the corrosive action 

 of the weather. (For specifications see Appendix E.) Its life is 15 to 30 years and 

 it has little or no wrecking value when removed. 



Hard-drawn coppei\ wire' possesses great conductivity and high tensile strength 

 and does not deteriorate when exposed to the weather. It is therefore well adapted 

 for telephone lines. More difficulty is encountered, however, in obtaining good elec- 

 trieal joints when splicing copper wire than when splicing iron wire. Copper wire is 

 of particular value where unusual construction is required, such as on very important 

 trunk lines over 125 miles in length, on metallic circuits, etc. It lasts almost 

 indefinitely and has a wrecking value equal to 80 per cent of its first cost. 



2 1 STANDARD CONSTRUCTION 



A one-wire line (grounded circuit) of No. 9 B.W.G., Best Best galvanized-iron 

 wire will be the standard construction on the forest reserves. No other method 

 ishould be used unless the permission of the district inspector is first obtained. If 

 the line is located outside of the reserve where there are no trees, No. 12 B.W.G. 

 galvanized wire may be Used, provided the length is short. Metallic circuit lines 

 are used only where there is outside interference, such as cross-talk, induction, or 

 trouble from power-transmission lines'. It is not possible to talk any farther over a 

 metallic circuit line than over a grounded circuit line provided the grounds of the 

 latter are made properly. Where the length of a line exceeds 125 miles it will prob- 

 ably be necessary to use copper wire. This cannot be used with swinging insulators 

 and will not be employed except on a strictly pole line. Where necessary, a two-wire 

 line (metallic circuit) of copper wire may be used. 



For spans up to 500 ft. the No. 9 galvanized-iron wire should be used, except 

 when the circuit is of hard-drawn copper wire. For longer spans steel wire or other 

 forms of special construction will be necessary. No. 12 New British Standard gauge 

 (N.B.S.G.) hard-drawn copper wire should not be used on spans longer than 300 ft., 

 nor No. 14 N.B.S.G. hard-drawn copper wire on spans longer than 200 ft. If the 

 circuit is of No. 12 N.B.S.G. hard-drawn copper wire and it is necessary to make 

 spans longer than 300 ft., No. 8 N.B.S.G. hard-drawn copper wire should be used 

 for the spans from 301' to 500 ft. If the circuit is of No. 14 N.B.S.G. hard-drawn 

 copper wire and it is necessary to make spans longer than 200 ft., No. 12 N.B.S.G. 

 hard-drawn copper wire should be used on spans from 201 to 300 ft. 



3 CAUTIONS 



Great caution must be used during lightning storms'. While lightning is being 

 discharged in the vicinity of the work, and as long as there is any danger from this 

 source, no line wire or any wire electrically connected .should ~be handled or touched. 



4 STRINGING WIRE 



There are several satisfactory methods of removing the wire from the reel, and 

 which one to use will be determined by the conditions in each particular case. A 

 man familiar with the location of the line and with the transpositions should be in 

 charge of the Unreeling of the wire. In paying out the wire care should be taken 

 to place it on the proper side of poles or trees, in order to avoid cutting it. Splices 

 should be as few in number as possible. 



When the conditions permit the use of a wagon, the reel may be placed in the 

 back and the wire laid upon the bracket? as fast as the wagon proceeds. 



Another method is to have the wire pulled out by a horse, either with a rope 

 that can be released instantly, between the ends of the wire and the traces of the 

 horse, or by tying the end of the wire to the horn of the saddle, with a man watching 

 the reel. Where the line is very crooked the reel should be placed at less 1 than one- 

 half mile from the starting point. 



