Change List for this Rule

 

General Order 95

 

Section IV

 

Strength Requirements for All Classes of Lines

 

49.4        Conductors

 

A.      Material

Conductors shall be of copper, copper–covered steel, bronze, stranded cable composites of any of the foregoing, aluminum, aluminum cable steel reinforced, galvanized iron, galvanized steel or of other corrosion–resisting metal not subject to rapid deterioration, except that in common neutral systems the provisions of
Rule 59.3–A shall also apply.

 

B.      Size

The minimum sizes of conductors which shall be used in spans of 150 feet or less under the several classes of construction and loadings in both urban and rural districts are specified in
Table 8 . Larger conductors than those specified in the table will often be necessary to maintain reasonable sag and at the same time provide the required safety factors of Rule 44 , ground clearances of Table 1 , and wire clearances of Table 2 .

Conductors of the sizes specified in
Table 8 may be used in spans longer than 150 feet, except when specifically prevented by Rule 49.4–C , provided the sags and conductor positions are so adjusted that the allowable working tensions and clearances of this Order are not violated.

The common neutral conductor in common neutral systems shall conform to the requirements of Rule 59.3–B in addition to the above requirements.

 

Table 8: Minimum Conductor Sizes (150–Foot Spans or Less)

Loading Conditions and Grade of Construction 

Material or Type of Conductor

Soft or Annealed Copper

Hard–Drawn or Medium Hard–Drawn Copper

Stranded Aluminum

Aluminum Cable SteelReinforced

Copper Covered Steel, Bronze or Composites

Galvanized Iron or Galvanized Steel


AWG

AWG

AWG

AWG

AWG

 

Heavy Loadging

Grade " A"

4

6

1

4

6

¼  inch Diameter Strand

Grade " B" (a) (h)

4

6

1

6

8

9   BWG

Grade " C" (h)

4

6

1

6

8

9 BWG

Light Loading

Grade " A"

4

6

1

4

8

¼  inch Diameter Strand (b)

Grade " B" (a) (c) (h)

6

6

1

6

8

9 BWG

Grade " C" (c) (h)

6

8

1

6

10

9 BWG

Heavy and Light Loading

Supply Service Drops Crossing Trolley Wires

8

10

-

-

12

-

Other Supply Service Drops

10

10

-

-

12

-

Grade " F" , Single Conductors (d)

-

(e)

-

-

(e)

14 BWG

Grade " F" , Paired Conductors (d)

-

14(f)

 

 

17 (g)

-

 

a)      Communication conductors crossing over major railroads may be smaller but shall be not less than as specified in Rule 113.4 .

 

b)      Three–sixteenth–inch strand may be used upon special permission of this Commission.

 

c)      May be smaller but shall provide tensile strength not less than #8 AWG soft copper, if less than 750 Volts, as per Rule 49.4–C2 .

 

d)      Communication service drops over supply lines shall conform to Rules 32.2–F and 32.2–G .

 

e)      #12 AWG or #14 NBS.

 

f)      Paired wire may be smaller per Rule 49.4–C7b .

 

g)      High strength paired wire may be smaller per Rules 49.4–C7b and 49.4–C8 .

 

h)      May be reduced per Rule 49.4–C3 .

 

C.      Strength

 

(1)        Heavy Loading Districts: Conductors in Grade “A” construction and in spans exceeding 150 feet shall have a tensile strength not less than that of #4 AWG medium–hard–drawn copper, and said conductors shall preferably be stranded.

   

(2)       Light Loading Districts: The following requirements apply for various grades of construction and span lengths.

Conductors in Grade “A” construction in spans exceeding 150 feet and not exceeding 300 feet in length shall have a tensile strength not less than that of #6 AWG medium–hard–drawn copper.

Supply conductors of less than 750 volts in Grade “B” or “C” construction in spans not exceeding 150 feet in length shall have a tensile strength not less than that of #8 AWG soft–drawn copper.

 

(3)        Heavy or Light Loading Districts: Where signal or communication lines take Grade “B” or “C” classification other than at railroad crossings, a minimum size of #8 AWG medium–hard–drawn copper or its equivalent in tensile strength may be used.

 

(4)       Conductors of Voltages Exceeding 17,000 Volts: Conductors of voltages exceeding 17,000 volts crossing conductors of less than 17,000 volts, or crossing a public highway shall have a strength at least equal to #4 AWG stranded medium–hard–drawn copper. In lieu of this, the conductors carrying more than 17,000 volts shall, at the point of crossing, be supported on poles of such height and so placed that under no circumstances can the conductor of over 17,000 volts, in case of breakage of same or otherwise, come in contact with any conductor carrying less than 17,000 volts, or fall within a distance of 10 feet from the surface of any public highway.

   

(5)       Sags and Tensions: Conductor sags shall be such that under the loading conditions specified in Rule 43 the tension in the conductors shall not be more than one–half the breaking strength of the conductor, other than communication circuits. The use of sags greater than the allowable minimum may be desirable in order to reduce working tensions.

Where the minimum size pins are used, the conductor tensions shall be limited to 2,000 pounds when applying the double arm, pin and conductor fastening provisions of Rules
49.2 and 49.3 .

 

(6)       Splices: Splices in line conductors shall be in accordance with the requirements of Table 4, except as provided in Rules 103.1–A and 113.1–A .

 

(7)       Service Drops:

 

a)       Supply: The minimum sizes shall apply only where the span does not exceed 150 feet. The minimum for supply lines of like voltage and grade shall apply when the service drop is in excess of 150 feet. Supply service drops of 0-750 volts shall, in all cases, have a weather–resistant covering equivalent to standard double braid weatherproofing except for multiple conductor service drop cable with a bare neutral conductor provided that the attachment of such cable at the pole and building ends shall be by means of an insulator.

 

Note:      Revised May 29, 1951 by Resolution No. E–756 and September 18, 1968 by Decision Number 72984.

 

a)       Communication: Communication service drops of #16 AWG paired copper wire may be used, provided they do not cross over supply lines, trolley contact or feeder conductors, or railways.

Paired wire communication service drops of #18 AWG high strength bronze or high strength copper–covered steel may be used provided the breaking strength of the pair is not less than 340 pounds.

 

(8)       Communication Line Conductors: Paired wire of #18 AWG high strength bronze or high strength copper–covered steel may be used as communication line conductors provided the breaking strength of the pair is not less than 340 pounds.

 

D.       Replacements (See Rule 44.3 )

 

E.      Connections

All electrical connections shall be of suitable electrical and mechanical design.