Some Effects of Tension on Static Wire Fatigue in New England

A review is made of the various factors affecting fatigue stress in overhead static wires. A practical limit of 20% UTS is found for the allowable operating tension to insure against fatigue damage. The calcu-lated bending stresses due to aeolian vibration are shown to increase as the 3/2 power of tension. Comparison of two static wires presently in service in New England indicates that the present practice of setting tension at 12.5% UTS bare @ 0°F provides an adequate margin of safety against fatigue damage, and that increasing initial tension to limit sag under iced conditions would not return benefits commensurate with the increased risk of fatigue damage.