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General Order 64-A

 

Section V

 

Detailed Construction Requirements For Supply Lines

(Class H, L and T Circuits)

 

54.8    Service Drops.

 

A.    General Clearances

 

(1)    Normal:  (See Table 1, Column B.)

 

(2)    Above Thoroughfares:  Service drops of 0-750 volts shall have a clearance of not less than 18 feet (Table 1, Case 3) over the traveled portions of thoroughfares.  This clearance may be reduced to 16 feet at the curb line of public thoroughfares.  Over private driveways and lanes this value may be further reduced to afford clearances to loads, the heights of which are governed by porches, awnings, etc., but in no case less than 10 feet.  (See App. G, Fig. 54.)

 

(3)    Above or Below Communication Circuits:

 

a)    Crossing more than 6 feet from pole:  Service drops of 0-750 volts may cross above or below open wire communication circuits or above communication cables at a distance of not less than 2 feet, provided the crossing is not within a distance of 6 feet from any pole other than the service pole.

 

b)    Clearance Cross Arms:  Service drops of 0-750 volts may be supported on a clearance cross arm at a distance of not less than 2 feet vertically above or below either supply circuits of 0-750 volts or communication circuits of open wire; also not less than 2 feet above circuits in cable, where such installations are necessary to obtain a crossing, provided the supply service drop conductors are at least 25 inches horizontally from the center line of the pole or are carried on a clearance arm in fiber conduit from end to end, placed on the underside of the arm and attached to suitable brackets at each end of the arm.  Service drop installed in accordance with this rule will not entail any change in the communication conductors supported on the pole.  (See App. G, Fig. 8.)

 

c)    Pole Top Extensions:  Service drops of 0-750 volts may be carried in a clearance crossing on pole top extensions or brackets above either supply circuits of 0-750 volts or communication circuits with a minimum vertical conductor separation of 2 feet, provided the conductors clear the center line of the pole (projected) 25 inches, horizontally, and also provided the service drop conductors clear the outside pin position conductors of the circuit not less than 2 feet.  Where, in addition to the pole top bracket or extension, a bracket is used on the end of the line crossarm and the supply service drop conductors are supported between the two, a minimum clearance of 12 inches will be permitted at the point of the crossing of the outside conductor pin positions.  In such construction it is recommended that the crossarm of the extension be of wood.  Such service drops installed in accordance with this rule will not entail any change in the communication conductors supported on the pole.  (See App. G, Figs 8 and 86.)

 

(4)    Above or Below Communication Service Drops:  Service drops of 0-750 volts may cross above or below communication service drops at a vertical clearance of not less than 2 feet.

 

(5)    Above Trolley Contact Conductors:  Service drops may be installed above trolley contact conductors, including messengers in catenary construction, of 0-750 volts at a vertical distance of not less than 4 feet, provided they clear the top of rails a vertical distance of 26 or 23 feet, depending on whether the railroad crossed does or does not transport or propose to transport standard freight cars.  (See Rule 74.4-B.)

 

(6)    Clearance From Buildings and Structures:  Service drops shall be so arranged as to hamper and endanger fireman as little as possible in the performance of their duties.

A clearance of 8 feet for service drops shall be maintained except on the premises served.  This clearance may be reduced to 2 feet over roofs of one-quarter pitch (26 from the horizontal) or greater.  Service drops of 0-750 volts are not required to clear buildings any specified horizontal distance, but shall be so installed that they clear fire escapes, exits, windows, doors and other points at which human contact might be expected, a horizontal distance of 3 feet.  Where attached to the surface of buildings the installation shall be made in accordance with the electrical safety orders of the Industrial Accident Commission.

 

(7)    Clearance Between Conductors:  Service drops of 0-750 volts shall be so installed that the conductors of opposite polarity (other than multiple conductors) clear each other, under all conditions, not less than 3 inches.

 

B.    From Combination Arms.  (See App. G, Figs 40 to 53.)

In addition to the above clearances, the following rules apply:

 

(1)    Line Arms:

 

a)    General:  In systems where conductors of 0-750 volts are installed on the same crossarm with conductors of these two classifications are on opposite ends of the crossarm with a minimum horizontal separation of 36 inches, service drops may be run directly from such crossarm, provided such service drops do not cross conductors of the other classification.

 

b)    Service Drops, 0-750 Volts:  In systems where conductors of 0-750 volts are installed on the same crossarm with conductors of 750-7500 volts and the conductors of these two voltage classifications are on opposite ends of the crossarm with a minimum horizontal separation of 42 inches, service drops of 0-750 volts may be run directly from the 0-750 volt side of the combination arm and may cross below the 750-7500 volt conductors of the same arm at a minimum vertical separation of 2 feet, provided the point of crossing of the service wires below the 750-7500 volt conductors is not less than 6 feet radially from center line of the pole.

 

c)    Service Drops, 750-7500 Volts:  In systems where conductors of 0-750 volts are installed on the same crossarm with conductors of 750-7500 volts and the conductors of these two voltage classifications are on opposite ends of the crossarm with a minimum horizontal separation of 42 inches service drops of 750-7500 volts may be run directly from the 750-7500 volt side of the combination line arm and may cross below the 0-750 volt conductors of the same arm at a minimum vertical separation of 2 feet, provided the point of crossing of the service wires below the 0-750 volt conductors is not less than 6 feet radially from center line of the pole.

 

(2)    Buck Arms:  In systems where conductors of 0-750 volts are installed on the same crossarm with conductors of 750-7500 volts and the conductors of these two voltages classifications are on opposite ends of the crossarm with a minimum horizontal separation of 42 inches, service drops may be run directly from related line buck arms or service buck arms installed with a minimum 2-foot vertical conductor separation, under the following provisions:

 

a)    Service Drops, 0-750 volts:  Line buck arms (single) from which service drops of 0-750 volts are run should be installed on the side of the pole below conductors of 0-750 volts of the related arm.  If placed on the opposite side of the pole they shall be considered as double arms and the No. 1 pin position, designated from the pole, on the 750-7500 volt side of the line arm must be left vacant and service wires crossing below conductors of this voltage classification must not pass under that side of the line arm within the third pin position.  Such crossings of 0-750 and 750-7500 volt conductors must not have less than a 2-foot vertical separation.

Service buck arms (single) must be installed on the side of the pole below the conductors of 0-750 volts of the related arm, and the minimum vertical separation of the service conductors at the point of crossing under conductors of 750-7500 volts shall not be less than 2 feet.

 

b)    Service Drops, 750-7500 Volts:  Line buck arms (single) from which service drops of 750-7500 volts are run should be installed on the side of the pole below conductors of 750-7500 volts of the related arm and unless the No. 1 and 2 pin positions, designated from the pole, on the 0-750 volt side of the line buck arm are left vacant, the service wires below the line conductors of 0-750 volts must not pass under that side of the line conductors of 0-750 volts must not pass under that side of the line arm within the outside pin position.  If placed on the opposite side of the pole, they shall be considered as double arms and the No. 1 pin position, designated from the pole, on the 750-7500 volt side of the line buck arm must be left vacant and the service wires below the conductors of 0-750 volts must not pass under that side of the line arm within the outside pin position.  Such crossing of 0-750 volt and 750-7500 volt conductors must not have less than a 2-foot vertical separation.

Service buck arms (single) must be installed on the side of the pole below the conductors of 750-7500 volts of the related arm; the conductors being maintained on one side of the arm only, with the No. 1 pin position, designated from the pole being, left vacant and service wires crossing below the 0-750 volt conductors must not pass under that side of the line buck arm within the outside pin position.  Such crossing of 0-750 and 750-7500 volt conductors must not have less than a 2-foot vertical separation.

 

c)    Service Drops, 0-750 and 750-7500 Volts:  Service drops of these voltages may both be run from combination line buck arms, provided neither class of service wire crosses conductors of the other classifications.

Service drops of both classifications may be run from a service buck arm provided they comply with Rule 54.8-B.

 

C.    From Racks.

Service drops may be run directly from low voltage racks, provided the climbing space requirements of Rule 54.9-B4 are maintained.