Selection of cable sheath lead alloys for fatigue resistance

This study evaluates the resistance to fatigue cracking of lead cable sheaths. Strains were measured in cable sheaths in service and criteria for acceptable fatigue life were established from these data. A fatigue machine for applying cyclic strains to specimens cut from samples of lead cable sheath was designed and built. Test results obtained with this machine on samples of eleven standard lead-based sheathing alloys are presented and discussed in relation to the criteria developed from the field data. A number of commonly used lead alloys is shown to have insufficient fatigue resistance to ensure 40 years of trouble-free service.