Evaluation of Solderless Wrapped Connections for Central Office Use

Since 1952, when the solderless wrapped connection first was described publicly, 1 its use in telephone central offices has grown steadily. Several hundred million solderless connections are being wrapped annually in the Bell System today, and the growth is continuing. T h e tangible and immediate results of solderless wrapping have been gratifying. For example, the use of solderless wrapping has reduced manufacturing costs by speeding up m a n y wiring operations and by reducing troubles caused by wire clippings and solder splashes. Furthermore, since solderless wrapping avoids the risk of damaging heatsensitive insulation by soldering operations, it has made widespread use of plastic-insulated wire practicable, and this is leading to substantial additional savings. In the end, however, these savings could be illusory if the use of solderless wrapped connections degraded telephone service or increased t h e 1033 103(3 T H E BELL SYSTEM T E C H N I C A L J O U R N A L , J U L Y 1(J5(J maintenance effort required in the telephone plant. T h e laboratory evaluation of solderless wrapped connections has been continued, therefore, in order to assess the risk of deterioration in service and to provide guidance for t h e design of connections t h a t are most likely to be reliable. This work has revealed certain limitations of solderless wrapped connections, but, at the same time, it has provided considerable assurance t h a t properly designed and properly made connections will be reliable in central office service.