APPLYING CARRIER TELEPHONE SYSTEMS 549 



Selection of Cables to be Equipped 



Where more than two cables existed on a route selected for carrier 

 operation, a number of factors influenced the selection of cables to be 

 equipped initially. Among these were the ages of the cables, their 

 makeup, specific route, number of branch cables and open wire junc- 

 tions, and lengths of underground cable involved. Between Detroit 

 and South Bend there were but two cables on the route selected and 

 hence no selection was necessary. Between New York and Washing- 

 ton on the New York-Charlotte route all cables are underground, and 

 since there were from three to six cables in each repeater section, the 

 two cables which it was decided to employ were selected because they 

 were relatively new and had the smallest number of branches. From 

 Washington to Petersburg, Va., there were two cables, while between 

 Petersburg and Charlotte there was but one cable and it was necessary 

 to install a small second cable chiefly for carrier operation. 



The Petersburg-Greensboro section of this second cable was in- 

 stalled one year ahead of the carrier application in order to make 

 use of part of its conductors which were loaded for voice frequency 

 operation. This cable is made up in most sections of 32 quads of 

 19-gauge conductors, of which 20 are loaded with H-88-50 loading 

 units, leaving 10 quads non-loaded for carrier use and two for main- 

 tenance purposes. 



The second cable in the Greensboro-Charlotte section was installed 

 coincidentally with the installation of the initial carrier systems. This 

 cable contains 61 non-quadded pairs throughout, except in certain 

 sections where it also contains some loaded conductors for short voice 

 frequency circuits. Paired construction was used because it was ex- 

 pected to be slightly more economical and temporary voice usage of 

 the conductors was not planned. 



One additional factor which, in special cases, influences the selection 

 of cables is that of carrier repeater spacing. This is brought about by 

 the fact that on multi-cable routes all of the cables may not follow 

 exactly the same route. For example, one cable may be aerial and 

 the other underground, and the two may be separated in some sec- 

 tions; or underground cables, for conduit reasons, may follow different 

 routes. It is desirable that the two cables used be near each other at 

 repeater points.^ 



One interesting feature in the construction of the Greensboro- 

 Charlotte Cable is the method by which the cable was attached to the 

 messenger. The cable was lashed to the messenger by means of a 

 galvanized steel wire continuous between poles, as shown in Fig. 2. 

 This method of installation is expected to reduce buckling, ring cuts, 



