General Order 95

Strength Requirements for All Classes of Lines

49.7     Messengers and Span Wires

A.      Material

Messengers and span wires shall be stranded and of galvanized steel, copper–covered steel or other corrosion–resisting material not subject to rapid deterioration.

B.      Strength

Messengers and span wires shall be capable of withstanding, with safety factors as specified in Rule 44 , the tension developed because of the load they support combined with the loading conditions specified in Rule 43 . An allowance of 200 pounds of vertical load for a man and cable chair shall be made in computing tensions in messengers and span wires which support cables except in the case of short spans which are not required to support workmen or where the ice loading specified in Rule 43.1–B would exceed the allowance for the man and cable chair.

Strength of guys supporting messenger loads shall be such that the safety factor of such guys is not less than the safety factor required of the messenger as specified in Rule 44 . It is recommended that overhead guys shall be the same size as the suspension strand and that anchor guys shall be enough larger than the suspension strand to compensate for the angle between the plane of the horizontal load of the suspension strand and the line of the guy.

C.      Supports

Messengers supporting cables shall be attached to poles or cross–arms with hardware which provides safety factors at least equal to those specified in Rule 44 , based on the weight of the cable plus an allowance of 200 lbs., for the man and cable chair. If in heavy loading areas the specified ice load exceeds in weight the 200 lbs. allowance, such ice load shall be used in making the calculations in preference to the weight of the man and cable chair. All hardware subject to injurious corrosion shall be protected by galvanizing, painting or other suitable treatment.

D.      Replacements (See Rule 44.3 )