Strength Requirements for All Classes of Lines

Element of Line	Grades of Construction
	Grade " A"	Grade " B"	Grade " C"	Grade " F"
Conductors, splices and conductor fastenings (other than tie wires)	2	2	2	1
Pins	2	2	2	1
Pole line hardware	2	2	2	2
Line Insulators (mechanical)	3	2	2	2
Guy insulators (mechanical)
Interlocking	2	2	2	2
Noninterlocking wood	3	3	3	-
Noninterlocking glass fiber	3	2(a)	2(b)	-
Guys, except in light loading rural districts	2	2	2	1.25
Guys in light loading rural districts	2	1.5	1.5	1.25
Messengers and span wires	2	2	2	2
Foundations against uplift	1.5	1.5	1.5	-
Foundations against depression	3	2	2	-
Poles Towers and Structures
Wood poles	4	3	2	1
Metallic service and meter poles	-	2	2	-
Structural or tubular metallic poles, towers, structures, crossarms and metallic members of foundations	1.5(c)	1.25(c)	1.25(c)	-
Reinforced concrete poles	4	3	3	-
Prestressed concrete poles, structures and crossarms	1.8	1.5	1.5	-
Other structural materials	1.5	1.25	1.25	-
Crossarms
Wood	2	2	2	1
Steel	1.5	1.25	1.25	-
Concrete	1.8	1.5	1.5	-
Other structural material	1.5	1.25	1.25	-

(a) Insulators are to be replaced before safety factors have been reduced (due to deterioration or changes in construction, arrangement, or other conditions subsequent to installation) to less than 95 percent of the safety factor specified in Rule 44.1 .

(b) Insulators are to be replaced before safety factors have been reduced (due to deterioration or changes in construction, arrangement, or other conditions subsequent to installation) to less than 75 percent of the safety factor specified in Rule 44.1 .

(c) For aluminum members subject to tension caused by one or more estimated loads and where the critical load combination for the tension member would not endanger adjacent compression members, the factor of safety on ultimate tension shall be 2 for Grade “A” construction and 1.67 for Grades “B” and “C” construction.

Note:      Revised July 26, 1966 by Decision No. 71009 January 6, 1968 by Decision No. 73455 March 30, 1968 by Decision No. 73813 February 13, 1974 by Decision No. 82466 and January 21, 1992 by Resolution SU–10.