General Order 64-A
Detailed Construction Requirements For Trolley Lines
(Class T Circuits)
A. Span Wires
(1) Supporting One Trolley Conductor: Span wires not including bracket span wires supporting or attached to wires which support contact conductors shall be insulated as follows:
One suitable and effective insulator (preferably of the interlocking strain type) shall be inserted in the span wire between 4 feet and 5 feet (measured along the span wire) from each suspension to point of support of the trolley contact conductor and its appurtenances which have electrical contact therewith. Where the span wire angle is so small that this strain insulator will interfere with the movement of the current collecting device, such insulator may be installed more than 5 feet (measured along the span wire) from the trolley contact conductor, but shall not, in any case, be more than 4 feet in a perpendicular direction from the trolley contact conductor.
A second suitable and effective insulator (preferably of the interlocking strain type) shall be inserted between 6 feet and 9 feet from the pole or structure, depending on a 4 foot minimum separation of the insulators. Where the distance from the pole or structure to the trolley contact conductor is less than 14 feet, a 4 foot minimum separation between the insulator shall be maintained wherever practicable. The clearance of the second insulator shall at all times be not less than 15 inches from the center line of the pole and outside of the climbing and working space. Where the attachment is made to a building, the clearance of the insulator from the building shall be not less than 3 feet.
Where the support is a wooden pole and all facilities supported is a wooden pole all facilities supported thereon are of one ownership and are operated and maintained by the same crews, the second insulator may omitted. (See App. G, Figs 70-71.)
(2) Supporting Two or More Trolley Conductors: A span wire supporting two or more trolley contact conductors requires no insulator between the suspensions of such conductors provided these suspensions are not more than 18 feet apart.
(3) Feeder Cables Used As Span Wires: Such feeder span cables shall be insulated as follows:
One insulator (preferably of the interlocking strain type) shall be placed outside of the climbing and working space at a distance not less than 15 inches from the supporting structure, except where only Class T circuits are installed on the structure, in which case the clearances of Table 1, Case 7, need not apply. The second insulator (preferably of the interlocking strain type) shall be installed at the point where the feeder span terminates, which point shall be not less than one foot nor more than 5 feet beyond the last trolley contact conductor to which it is attached, and a third insulator (preferably of the interlocking strain type) at a distance of not less than 6 feet nor more than 9 feet (measured along the span wire) from the pole or structure.
Where catenary construction is used, this second insulator shall be place at the point where the feeder span terminates, which point shall be not less than one foot plus the distance between the messenger and the trolley nor more than 5 feet beyond the last trolley contact conductor to which it is attached.
In lieu of this type of construction it is recommended that where there are two or more parallel trolley contact conductors the feeder cable be installed as an auxiliary span at a distance not less than 18 inches above the span wire installed as per Rule 77.6-A1. The attachment to the trolley contact conductor shall preferably be placed on the side of the trolley contact support opposite approaching traffic.
If the feeder cable crosses the pole laterally, it shall not impair the climbing or working spaces, and it is recommended that it be installed in fibre conduit or other suitable protective covering. (See App. G, Figs. 72-73-74.)
A backbone which is supported on insulators on crossarms, pole brackets or trolley brackets, shall be treated as a trolley line conductor except from a point between 6 feet and 9 feet measured along the line of the backbone in the direction of its dead end from the first and last insulator supports. From these points to its dead end attachments it shall be treated as a guy.
A backbone run between and attached directly to poles shall have insulators installed in it between 6 feet and 9 feet from the points of attachment to the poles, measured along the line of backbone. Each pull-off from the contact conductor to that portion of the backbone between the two insulators specified above shall have an insulator installed in it at a distance between 4 feet and 5 feet from the contact conductor; or if this is not practicable the insulator shall be installed in it as far as possible from the contact conductor to a point between the backbone insulator and the supporting structures shall have two insulators installed in it. (See App. G, Figs 75 and 76.)
In bracket construction span wires which support, or are attached to span wires which support trolley contact conductors or appurtenances in electrical contact therewith, shall be insulated as follows:
(1) Normal: A suitable and effective insulator shall be inserted in the span wire between the suspension of the trolley conductor and each point of support of the span wire, such insulators to be not less than one foot from the trolley contact conductor. (See App. G, Figs 77 and 78.)
(2) Hanger: The suspension or hanger supporting the trolley contact conductor shall be insulated for the trolley voltage.
Exceptions: Where the brackets are supported on wood
poles which support no other conductors than those of one ownership, Rule
77.6-C1 need not apply. (See App. G,
Figs 79 and 80.)
Where brackets are suitably insulated along their length perpendicular to the poles and from the span wire, that part of Rule 77.6-C1 which prescribes an insulator between the suspension and the point of bracket support need not apply. (See App. G, Fig. 81.)
In placing insulation in metal brackets and lift spans a distance of at least one foot radially must be maintained between the insulators and the trolley contact conductor. (See App. G, Fig. 82.)
Feeder Conductors: Feeder wires used as bracket span wires
shall be well insulated except at points of contact with trolley contact
conductors. One insulator (preferably
interlocking) shall be placed at a distance of not less than 15 inches from the
supporting structure, except where only Class T circuits are installed, in
which case a lesser clearance may be obtained.
Another insulator shall be placed at the point where the feeder
terminates. (See App. G, Figs. 83.)
In lieu of this type of construction, it is recommended in high-speed lines that the bracket span be installed as per Rule 77.6-C1 and that the feeder span be installed as per Rule 77.6-C1 and that the feeder span be installed as a bracket guy or lift span. One insulator shall be installed along this lift span so that the horizontal distance between the insulator and the supporting structure shall be not less than 15 inches, and another insulator shall be placed along the line of this lift span adjacent to the point off attachment to the bracket.
Where a messenger is treated as a guy, the requirements specified for guys shall be met.