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General Order 64-A


Appendix B


Mechanical And Loading Data For Conductors


The tables included in these appendices contain mechanical data of copper wire, copper covered wire, steel wire, iron wire and cable most commonly used in electrical supply and communication lines; also, the maximum wire loadings for light and heavy loading districts as outlined in Section IV.


In the compiling of the curves in Appendix C the values of the tables herein, together with the following data, have been used:


Modulus of Elasticity:

Copper covered steel, solid

20,000,000 lbs. per sq. in.

Copper covered steel, stranded

17,000,000 lbs. per sq. in.


16,800,000 lbs. per sq. in.

Steel, solid

29,000,000 lbs. per sq. in.

Steel, stranded

21,000,000 lbs. per sq. in.

Iron, drawn

26,000,000 lbs. per sq. in.


Coefficient of Linear Thermal Expansion:

Copper covered steel

0.72 x 10-5 per degree F.


0.96 x 10-5 per degree F.


0.67x 10-5 per degree F.


The breaking load of stranded conductors has been taken as 90 percent of the sum of the breaking loads of individual strands.



No. 14 Hard Drawn Copper Wire Solid Bare.

No. 15 Hard Drawn Copper Wire Solid Bare.

No. 16 Hard Drawn Copper Wire Stranded Bare.

No. 17 Soft Drawn Copper Wire Solid Weatherproof.

No. 18 Soft Drawn Copper Wire Stranded Weatherproof.

No. 19 Hard Drawn Copper Covered Wire Solid Bare.

No. 20 Steel Wire Solid Bare, Roebling (St. W.G.).

No. 21 Steel and Iron Wire Solid Bare, Birmingham (B.W.G.)

No. 22 Galvanized Steel Strands.

No. 23 Aluminum Steel Strands.

No. 24 Minimum Sags for Communication Conductors.