General Order 95
Detailed Construction Requirements for Communication Lines
(Class C Circuits)
The clearances for conductors as specified in
shall apply to cables and their messengers except where modified herein
and shall be measured to the nearest surfaces of the cable and messenger
assembly, including cable rings and messenger supports.
A. Above Ground (See
B. Above Railways and Trolley Lines
Which Transport Freight Cars (See
(2) Operated by Overhead Trolley:
The clearances specified in Table 1, Case 2, Columns A and B are based upon a maximum trolley pole throw of 26 feet.
Messengers and cables may have clearances above the rails or running surfaces used by trolley cars or coaches less than the distance specified in Table 1, Case 2, Columns A and B (26 feet) for trolley–throw clearance, provided the messengers and cables are not less than 4 feet above the trolley contact conductor and are encased in wood boxing or moulding 7/8 inch or more in thickness for distances of at least 2 feet horizontally from the vertical plane of each trolley contact conductor.
Where railways operated by overhead trolleys transport freight cars, the provisions of Rule 84.4–B1 also apply.
C. Between Conductors
The minimum horizontal and vertical clearances shall be those specified in Rule 38 , Table 2 (see also, Rule 32.2–D ) with the following modifications.
(1) Cable Conductors: Insulated cables (including rubber–insulated single
conductors, duplex, triplex, and paired conductors, whether single or grouped,
and whether with or without supporting messengers) are treated as single conductors,
and therefore no specified clearance is required between the individual conductors
which comprise them. The clearance of 3 inches required by
Table 2, Case 15, Column C,
likewise does not apply between different cables.
Between Separate Cables: The horizontal separation of 3 inches
specified in Table 2, Case 15,
, is not intended to apply between separate cables on crossarms.
Attached to Poles: On poles which carry no supply conductors or
crossarms, communication cables or messengers may be attached to the sides
of poles in any position within 3 feet of the top of the pole provided metal–sheathed
cables or messengers are separated from open wire conductors in this section
of the pole by a vertical distance of not less than 12 inches.
On poles where communication conductors are supported on crossarms and no supply conductors (except supply service drop clearance attachments) are attached, apply the provisions of Rule 84.4–D1 and Figure 84–2 .
Cables or messengers where attached to the surface of poles which support supply conductors, shall not be less than 6 feet vertically below the level of supply conductors.
clearance of 6 feet may be reduced to not less than 4 feet below supply
conductors of 0 - 750 volts provided a guard arm is placed above the messenger
and cable (or self–supporting cable) in accordance with the provision of
(see Rule 21.0–D
for guard arm definition). No cable or messenger shall be attached to the
surface of such a pole less than 2 feet below the lowest level of communication
conductors on crossarms unless a minimum horizontal separation of 30 inches
is maintained between the messenger or cable and the communication conductors
on the opposite side of pole.
Revised November 21, 1990 by Resolution SU–6.
(1) Cables or Messengers Supported on Crossarms: Cables on messengers
supported on crossarms shall have a clearance of not less than 15 inches
from the center line of poles which support supply conductors.
Cables or messengers supported on crossarms shall have a clearance of not less than 9 inches from the center line of poles which support only communication conductors.
Cables or Messengers Not Supported on Crossarms: Cables or messengers
may be attached directly to the surface of poles and the clearance specified
in Table 1, Cases 8 and 9
, shall not be held to apply provided all vertical clearances between conductors
are maintained as specified throughout these rules.
Colinear Lines (See Rule 84.4–D3
Cables or Messengers Passing Supply Poles and Unattached Thereto
(See Rule 84.4–D4
(5) Cables or Messengers Passing and Unattached from Nonclimbable Street
Lighting and Traffic Signal Poles or Standards (See
Note: Added January 8, 1980 by Decision
No. 91186 and Revised March 9, 1988 by Resolution E–3076.
E. Above or beside Buildings, Bridges and Other Structures
(See Rule 84.4–E
F. Between Cables and Messengers
Cables supported by messengers are not required to be any specified distance from their supporting messengers.
G. Between Messengers
No clearance between messengers is required where messengers of the same system branch or cross and the clearance specified in Table 2, Case 1, Column A , does not apply in such instances.
H. From Grounded Metal Boxes, Hardware and Equipment
Associated with Supply Lines
Cables and messengers installed on non–metallic poles or non–metallic structures shall have a minimum clearance of 48 inches below or 72 inches above grounded metal boxes, hardware or metal cases for equipment associated with supply lines.
(1) The 72 inches above may be reduced to 48 inches where there is not
a pole mounted communication drop distribution terminal above the grounded
metal box, hardware or metal case for equipment, or where the grounded metal
box, hardware or metal case for equipment is securely bonded to the communication
cable and/or messenger (see
(2) The 72 inches above may be reduced to 48 inches when the grounded metal
box, hardware or metal case for equipment is on the opposite side of a pole
from a pole mounted communication drop distribution terminal.
Added October 9, 1996 by Resolution SU–40.