General Order 95
Detailed Construction Requirements for Supply Lines
(Class H, L and T Circuits)
54.12 Low Voltage Extended Racks, 0 - 750 Volts (Conductors 15 inches
or More from Centerline of Pole, But Not Less than 3 inches from the
Surface of Pole)
Conductors of 0 - 750 volts may be attached to poles by means of vertical racks of insulators or individual extended supports in vertical rack configuration. Such construction is hereinafter termed “extended rack construction”. Where extended rack construction is employed, the following rules shall apply.
Note: For Low Voltage Rack Construction
(Conductors Less than 15 Inches from Centerline Of Pole, But Not Less than
2–1/2 inches from The Surface Of Pole) See
B. Pole Arrangement and Clearance
(1) Clearance from Poles: Conductors in extended rack construction
shall have minimum clearances of 15 inches from center line of pole and 3
inches from the surface of pole as specified in
Table 1, Column D, Cases 8 and 9
Conductor Arrangement: Where conductors, both line and service
drop, are supported by extended racks, such extended racks may be attached
to three sides of a pole (there being 4 sides) at the levels of any extended
rack group. Climbing space in conjunction with such attachments shall be
maintained as specified in Rule 54.12–F
C. Conductor Material
All conductors of a rack group in the same vertical plane shall be of the same material.
D. Conductor Spacing
and Spreader Brackets
(1) Vertical Separation: The vertical separation between conductors,supported
as a group in extended rack construction, shall not be less than 8 inches,
such separation to be maintained in a span by suitably insulating spreader
brackets attached to such line conductors within the span.
(2) Spreader Brackets: Spreaders shall be used at points in spans where
one or more midspan service drops are attached to and supported by the line
conductors. Also, spreaders shall be so spaced as to limit spans between spreaders
or between spreaders and poles to not over 135 feet.
Clearance between Conductor Levels
A vertical clearance shall be maintained between the top conductor supported in the extended rack group at one level and conductors supported on the same pole at the next level above as provided in Table 2, Cases 9 to 13 and for lead wires Rule 54.4–C6 .
Related Extended Rack Construction and Other Types of Construction:
Where conductors supported in extended rack construction are connected to conductors supported on other types of construction (crossarm etc.) climbing space shall be maintained in the same quadrant or on the same side of pole in accordance with climbing space requirements in Rules 54.7 , 54.9 , 54.10 or 54.12–F whichever is related to the climbing space selected.
Climbing Space in Extended Rack Construction
The climbing space in extended rack construction shall be maintained through the level of conductors supported in extended rack construction and for a vertical distance of not less than 4 feet above and below such conductors. The position of the climbing space through the level of conductors in extended rack construction shall be related to climbing space for conductor levels above and below such extended rack construction in accordance with Rules 54.7 , 54.10 , 54.11 and 93 . The depth of the climbing space shall be measured from the center line of the pole.
(1) Dimensions: The dimensions of the climbing space shall be 30 inches
square, and shall be provided on one side of the pole with the extremities
of such width equidistant from the centerline of pole. On poles on which transformers
are pole–bolted in line with primary conductors, a 30 inch square climbing
space shall be provided in one quadrant or one side of the pole (See
(2) With Conductors Deadended and on Corner Poles: On poles with the
extended rack conductors dead–ended and on corner poles, a 30 inch climbing
space shall be provided in one quadrant or on one side of the pole (see
(3) Allowable Climbing Space Obstructions: Allowable climbing space
a) Guys. However, not more than two guys having a vertical separation
of 18 inches or less can be installed in any 4–foot section of climbing space.
b) Suitably protected (covered only by wood, see
Vertical risers; or
Vertical runs; or
Such risers, runs, and grounds are allowable, provided that not more than
one is installed in any 4–foot section of climbing space.
c) Insulators and their attaching brackets may extend one–half their
diameter into climbing space.
d) Conductors may extend one–half their diameter into climbing space.
e) Street light brackets may extend one–half their diameter into climbing
space. Associated street light bracket struts are allowed in climbing space.
f) Operating rods (e.g., switch rods) and their associated hardware may
extend one–half their diameter into climbing space.
g) Bands, limited to 6 inches in width with no more than one band allowed
in any 24–inch section of climbing space (these limitations are excluded
for pole stubbing and pole splicing bands when pole step provisions are installed.)
h) Bolts and their washers.
The terminals or terminal fittings of risers or runs shall not be installed within climbing spaces.
Note: Rule 54.12 Added January 21, 1992, by Resolution SU–10 and revised October 9, 1996 by Resolution SU–40.