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 Conductor Steel Reinforced | 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 "C", Single Conductors (d) | - | (e) | - | - | (e) | 14 BWG |
| Grade "C", 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 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) | Rule 49.4–C3. |
Note: Revised February 5, 2014 by Decision No. 14-02-015.
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: Sags shall be such that under the loading conditions specified in Rule 43 the tension in the cable or conductor shall not be more than one–half of its breaking strength.
There are no strength requirements for the cable or conductor when supported by a messenger. See Rule 49.7-B for
the strength requirements for messengers supporting cables or conductors.
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.
Note:
Revised February 5, 2014 by Decision No. 14-02-015.
(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.