Change List for this Rule

 

General Order 95

 

Section VIII

 

Detailed Construction Requirements for Communication Lines
(Class C Circuits)

89.2    Construction and Operation

 

Private communication circuits shall be constructed and maintained throughout (by suitable coordination with supply circuits or by the use of arresters, drainage coils, insulating transformers, or other suitable devices) so as to prevent, under normal (neither transient nor fault) conditions, an induced potential in excess of 400 volts to ground or 750 volts between any two points on the circuit.

 

Private communication circuits or sections thereof shall be constructed and operated as Class C circuits, and shall be consistently so treated with regard to voltages, clearances and strengths of construction except as provided in Rule 89.2A where supported on the same crossarms with supply conductors.

 

See Rule 78.2 for provisions applicable to private communication circuits supported on trolley span wires.

 

Note:    Revised January 19, 1994 by Resolution SU25.

 

A.    Private Communication Circuits and Supply Circuits on the Same Crossarms (See Rule 32.4C )

 

(1)    Supply Conductors of 7,500 - 22,500 Volts, Same Ownership: Where private communication conductors are supported on the same crossarms with supply conductors of 7,500 - 22,500 volts, the private communication circuits shall have the strengths and clearances required for Class L circuits of 750 - 5,000 volts. The private communication conductors shall be on opposite ends of the arms from the supply conductors and shall be separated a horizontal distance of not less than 36 inches from the nearest supply conductor. Where buck arms are used in connection with such circuit arrangement, the minimum vertical separation between related line and buck arms shall be 4 feet and the horizontal separation between the nearest conductors of the two classes of circuits on the same arm shall be not less than 36 inches plus any horizontal space provided by vacant pin positions which are required by climbing space rules.

 

Note:    Revised March 29, 1966 by Decision No. 70489 and August 9, 1966 by Decision No. 71094.

 

(2)    Supply Conductors of 750 - 7,500 Volts, Same Ownership: Where private communication conductors are supported on the same crossarms with supply conductors of 750 - 7,500 volts, the private communication circuits shall have the strengths and clearances required for Class L circuits of 0 - 750 volts. The private communication conductors shall be on opposite ends of the arms from the supply conductors with conductor clearances and the spacing between related line and buck arms in conformity with the requirements for combination arm construction (see Rules 32.4A3 , 54.4C2b and 54.7A ).

 

(3)    Supply Conductors of 0 - 750 Volts, Same Ownership: Where private communication conductors are supported on the same crossarms with supply conductors of 0 - 750 volts, the private communication circuits shall have strengths and clearances as required for Class C conductors except that the clearances from supply conductors of the same ownership shall conform to the requirements of Class L circuits of 0 - 750 volts. The communication conductors shall preferably be located in the outer pin positions.

 

(4)    Supply Conductors of 0 - 750 Volts, Different Ownership: Supply circuits of 0 - 750 volts and private communication circuits of different ownership may be supported on the same crossarm, provided the two classifications of circuits are installed on opposite ends of the arm and the nearest conductor of the two classifications are separated a horizontal distance of not less than 36 inches. Services direct from such a crossarm are not permitted to cross conductors of other classification supported on the same crossarm.

 

(5)    Change in Location with Respect to Supply Conductors: At both ends of any section of private communication circuits supported on the same crossarms with supply conductors in accordance with Rules 89.2A1 or 89.2A2 , suitable equipment shall be provided to prevent effectively the transmission, from one section of the line to another, of voltages exceeding 400 volts to ground or 750 volts between any two points of the circuit, including voltages caused under transient or fault conditions, by induction from or contact with the supply conductors supported on the same arms with the private communication conductors.

 

B.    Private Communication Circuits and Supply Circuits on the Same Pole

Where private communication circuits are supported on the same poles with supply conductors but not on crossarms which also support supply conductors, the clearance requirements for 0 - 750 volt supply conductors may be applied in lieu of the clearance requirements for Class C conductors, to the clearance between the private communication conductors and supply conductors of the same ownership.