PULP INSULATION FOR TELEPHONE CABLES 21 



Conclusions 

 A new type of insulated wire which is considerably cheaper than 

 paper ribbon insulation has been developed. The insulation is formed 

 from paper pulp directly on the conductor by a special type of paper 

 making equipment. This equipment is not critical to the kind of 

 pulp used but for the purposes of durability, strength and economy a 

 Kraft wood pulp has been used in telephone cables. The process has 

 progressed through the development stage and is now in continuous 

 operation in the commercial production of all the principal exchange 

 area cables of 24 and 26 A.W.G. conductors used in the Bell System. 

 Thousands of miles of lead encased pulp insulated cables, ranging in 

 size from the smallest consisting of 1 1 pairs to the largest consisting of 

 1818 pairs, are now giving satisfactory service and because of the sub- 

 stantial economies which the construction promises for the finer wire 

 cables, attention is being directed toward its possible application to 

 larger gauge cable conductors and to its use as an insulating medium 

 for other electrical circuits. 



