THE UNDERGROUND INSTALLATION OF UTILITIES 391 



and manufacturing equipment and components to make aesthetic 

 systems more economical. 



As a major supplier to the industry, the Electrical Products Divi- 

 sion of Kaiser Aluminum & Chemical Corp. has directed a sub- 

 stantial portion of its research and development programs to this 

 goal, and has been encouraged by the reception given new develop- 

 ments by both private and public utilities. The introduction of 

 new cable constructions and insulations is one of the important fac- 

 tors which have enabled the reduction of the cost differentials of 

 underground electrical distribution in the lower voltages and even 

 up to 35,000 volts with the resultant rapidly increasing growth of 

 URD installations. 



Progress is now being made on insulated conductors for higher 

 voltages. We ourselves are currently collaborating with a major 

 southeastern utility in a test installation of 115,000-volt cable utiliz- 

 ing plastic insulation in direct ground burial for underground trans- 

 mission. Although it is still too early to gauge the success of this 

 particular test, it is noteworthy that manufacture of cable of this 

 type has only recently become possible. 



While great strides have been and will be made in underground 

 distribution, industry attention has also been given to the improve- 

 ment in the appearance of overhead lines through the introduction 

 of more pleasingly designed equipment and conductors such as pre- 

 assembled aerial cable. 



As was brought out in panel discussions, extra high voltage trans- 

 mission presently has to be by overhead lines because of the extremely 

 high cost ratio of underground construction for this purpose. There- 

 fore it is desirable that every possible step be taken to improve the 

 appearance of EHV transmission lines. Because of its lighter weight, 

 aluminum conductors such as ACAR, a new type developed by 

 Kaiser Aluminum which eliminates the customary steel core, allows 

 towers to be placed farther apart; for example, four towers may fre- 

 quently be used per mile instead of five. 



Progress has also been made in reducing the cost, weight, main- 

 tenance, and silhouette of transmission towers. Aluminum guyed- 

 V and guyed-Y towers can be assembled away from the installation 

 site, flown there by helicopter and installed on a small concrete base. 

 From an aesthetic standpoint, the slim structures are less visible 

 against the skyscape, and it is not necessary to hack access roads for 

 trucks and workmen through the forest areas, either for installation or 

 maintenance. 



