General Order 64

Detail Construction Requirements For Supply Lines

63    Conductors.

(a)    Materials and Minimum Sizes:  All supply conductors shall be of copper, aluminum (with or without steel reinforcement) copper covered steel, or other material which will not corrode excessively under the prevailing conditions to which the conductor is subjected.

The minimum size of wires of various materials which shall be used for the several classes of construction and loadings are listed below.  These minimum sizes shall obtain in both urban and rural districts.  Larger sizes of wire than those shown in the table will often be necessary to maintain reasonable sag and at the same time provide the required safety factors of Section V, particularly when the span is long, and furthermore, in order to obtain the required clearance from the ground or from other conductors.

*3/16-in. strand may be used upon special authorization of the Railroad Commission

1.    Where spans exceed 150 feet in Grade “A” construction, conductors shall have a tensile strength of not less than No. 4 A.W.G. copper, and said conductor shall preferably be stranded; and further provided, that conductors of voltage exceeding 17,000 volts crossing conductors of less than 17,000 volts, or crossing a public highway shall have a cross sectional area equal to at least that used in the line outside of such crossing, except where the conductor used is of strength equal to No. 4 A.W.G. stranded copper or greater, in which case the conductor will be considered as complying.  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.

2.    No. 6 A.W.G. soft drawn copper shall not be used in heavy or light loading districts on spans exceeding 150 feet.  The minimum sizes for supply service drops shall only apply where the span does not exceed 150 feet.  Supply service drops of 0-750 volts shall, in all cases, have a standard double braid, weatherproof, insulated covering or other material equivalent thereto in insulating efficiency.

3.    In light loading districts No. 8 A.W.G. soft drawn copper may be used for Grade “B” or “C” construction in spans not exceeding 150 feet, provided the voltage is below 750 volts.

4.    Where signal or telephone lines take a Grade “B” or “C” classification in heavy or light loading districts, a minimum size of No. A.W.G. hard or medium hard drawn copper wire may be used.

(b)    Sags:  Overhead wires shall be strung with sags not less than those shown in Appendix C.

(c)    Wires Passing Through Tress:  When overhead wires pass through trees, safety and reliability of service demand that a reasonable amount of tree trimming be done in order that the wires may clear branches and foliage.

(d)    Wires or Cables Run Vertically on Poles:

1.    Vertical or lateral supply conductors of open wire construction (not in cable) should not be attached to the surface of the pole; installation of such conductors shall be on crossarms or other supports, arranged to maintain the clearance from poles structures and other wires, as specified previously in Tables 1 and 2, and protected as specified below.

2.    Vertical and lateral conductors of open wire construction (not in cable) may have lesser clearances than required in Table 1, if they have suitable insulating covering and are encased in conduit or other substantial casing, provided that the casing is equal in durability and insulating efficiency to a wooden casing not less than 1 ½ inch thick.  If steel poles or structures are used, this wooden casing is not required, provided the wires or cables are suitably insulated and enclosed in iron conduit, and further provided that both conduit and structure are grounded.

3.    Vertical risers from underground cables shall be enclosed in iron pipe (or metal conduit of equal strength) from the ground line to a point at least 8 feet above the ground.  This 8-foot (or longer section of pipe) section need not be covered with a wooden casing or any equivalent thereof.  If the riser be extended up the pole without being enclosed in an iron pipe, said riser shall be covered with a casing equal in durability and insulating efficiency to a wooden casing not less than 1 ½ inch thick.  Any portion of the riser or iron pipe enclosing the riser, extending within 8 feet of any supply conductor, shall be covered with a casing equal in durability and insulating efficiency to a wooden casing not less than 1 ½ inch thick.  This rule shall not be held to apply to that portion of the cable marked “X” on Fig 15, Appendix E, provided that the nearest terminal of the pothead on the cable is maintained the minimum distance from the center line of pole specified for wires in Case No. 6, Table 1.

4.    Ground Wires: Ground wires may be attached to or run on the surface of poles, provided said wires are enclosed in a casing equal in durability and insulating efficiency to a wooden casing not less than 1 ½ inch thick.  Should it be necessary to extend ground wires to a point above one or more crossarms on a pole, said wires shall be located to permit the extension of the protective casing; contact between the ground wire and crossarm braces, guy fastenings or other exposed metal parts shall be prevented, except where the grounding of such crossarms, braces, etc., is intentional.

5.    Pin Bonding Wires:  Wires used to bond pins, etc., together may be stapled to poles and no covering need be used over same, provided said bonding wires do not extend more than 2 feet below the lowest crossarm on which the pins are bonded.