240 BELL SYSTEM TECHNICAL JOURNAL 



and the exposures between particular circuits are likely to be long, joint 

 use is not always practicable. In these cases locations for separate 

 lines are usually available. 



Furthermore, joint use in rural areas is not always economical from 

 a purely construction standpoint due to the fact that relatively longer 

 spans can often be used on the power lines and both utilites are able 

 in many instances to use shorter and lighter poles than would be 

 practicable in joint use. Joint use with telephone toll circuits or 

 power transmission lines has not, in general, been found desirable. 

 Types of construction vary so widely and service requirements and 

 inductive effects are such that it becomes uneconomical to carry out 

 such construction. 



Conclusions 



Joint use of poles by power and telephone companies has many 

 advantages, both from the standpoint of the public and from the 

 standpoint of the wire using companies. This is especially true in 

 built-up communities. 



Important problems brought about by developments in practises, 

 particularly in the use of high voltage distribution, remain to be solved. 



Careful adherence to generally accepted practises with regard to 

 clearances, strength of construction, insulation and inductive coordin- 

 ation is necessary in order that the advantages of joint use can be 

 secured. 



In considering specific cases proposed for joint use, it is advisable that 

 all of these factors be studied cooperatively by the companies con- 

 cerned, to the end that good service, safety and economy by both classes 

 of utility may be promoted. 



It is important that everything practicable should be done to facili- 

 tate joint use construction and extend its usefulness. The Joint 

 General Committee of the National Electric Light Association and 

 Bell Telephone System is continuing its efforts in this connection. 



