Original General Order 95

Section V

Detailed Construction Requirements for Supply Lines

(Class H, L and T Circuits)

54.8    Service Drops, 0-750 Volts

A.    Material and Size

Supply Service drops of 0-750 volts shall be of material and size as specified in Table 8 and Rule 49.4-C7a and shall have a weather-resistant covering at least equivalent to double-braid weatherproofing.

B.    Clearances Above Ground, Buildings, Etc.

(1)    Above Public Thoroughfares: Service drop conductors shall have a vertical clearance of not less than 18 feet above public thoroughfares, except that this clearance may grade from 18 feet at a position not more than 12 feet horizontally from the curb line to a clearance of not less than 16 feet at the curb line, provided the clearance at the centerline of any public thoroughfare shall in no case be less than 18 feet. Where there are no curbs the foregoing provisions shall apply using the outer limits of possible vehicular movement in lieu of a curb line.

(2)    Above Private Thoroughfares and Other Private Property:

a)    Industrial or Commercial Premises: Over private driveways, lanes, or other private property areas accessible to vehicles on premises used for industrial or commercial purpose, service drops shall have a vertical clearance of not less than 16 feet.

b)    Residential Premises: Over private driveways or lanes or other premises used for residential purpose only, service drops shall have a vertical clearance of not less than 12 feet.  If the building served does not permit an attachment which will afford a clearance of at least 12 feet over such areas without the installation of a structure on the building to provide additional height, the vertical clearance of service drops of 0-300 volts only may be less than 12 feet but shall be maintained as great as possible and shall be not less than 10 feet.

(3)    Above Ground in Areas Accessible to Pedestrians Only:

a)    Industrial and Commercial Premises:  Over areas accessible to pedestrians only on premises used for industrial or commercial purposes, service drops shall be maintained at a vertical clearance of not less than 12 feet.

b)    Residential Premises: Over areas accessible to pedestrians only on residential premises, service drops shall be maintained at a vertical clearance of not less than 10 feet.  If the building served does not permit an attachment which will afford at least 10 feet clearance over such areas without the installation of a structure on the building to provide additional height, the vertical clearance of service drops of 0-300 volts only may be less than 10 feet but shall be maintained as great as possible and shall be not less than 8 feet 6 inches.  If the building served would require the installation of an attachment structure to provide height sufficient to afford a vertical clearance of at least 8 feet 6 inches, the full clearance of 10feet shall be maintained.

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

a)    Industrial and Commercial Premises: On premises used for industrial or commercial purposes service drops shall be maintained at a vertical clearance of not less than 8 feet over all buildings and structures.

Service drops 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 not less than 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, effective May 1, 1934.

b)    Residential Premises: On premises used for residential purpose only, service drops of 300-750 volts shall be maintained at a vertical clearance of not less than 8 feet over all buildings and structures.

The clearance above buildings of service drops of 0-300 volts shall be not less than the distance specified in Table 10.

a)    3/8 pitch is a approximately 37 degrees from the horizontal.

b)    No limit specified but the greatest clearance should be obtained.

Service Drops are not required to clear buildings on residential premises 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 not less than 3 feet.

C.    Clearances Between Supply Service Drops and Other Conductors

The clearance of supply service drop conductors from other conductors shall be not less than the minimum clearances specified in Rule 38, Table 2, Column D, with the following modifications:

(1)    From the Fire Alarm or Other Communication Line Conductors:

a)    Crossing in Spans: At crossing in spans, supply service drop conductors may have a clearance of less than 48 inches (Table 2, Case 3, Column; and Case 4, Column C) but not less than 24 inches above any communication line conductors or below communication line conductors not supported on a messenger, provided the crossing is 6 feet or more from any pole which does not support both conductors involved in the crossing (see App. G, Fig 42).

b)    Supported on the same Pole: Supply service drop conductors, other than those on a pole-top clearance attachment, may have a clearance of less than 48 inches (Table 2, Case 8, Column D; and Case 9, Column C) above or below communication line conductors supported by the same pole and not on a messenger provided such clearance is 6 feet or more from any pole which does not support both conductors involved, and provided clearances at least equal to those shown in Table 11 are maintained.

Supply service drop conductors may have a clearance of less than 48 inches (as specified in Table 2, Case 8, Column D; and Case 9, Column C) but not less than 24 inches above and laterally from communication line conductors supported on a messenger by the same pole provided such clearance is 6 feet or more from any pole which does not support both conductors.  The vertical clearances of not less than 24 inches above or 48 inches below communication conductors supported on messengers are not required where the supply service drop conductors are 24 inches or more horizontally from the vertical plane of the communication messenger.  (See App. G, Fig 42.)

(2)    On Clearance Crossarms: Supply service drops may be supported on a clearance crossarm at a vertical distance less than 48 inches (specified in Table 2, Case 8, Column D, and Case 9, Column C) but not less than 24 inches above or below either supply circuits of 0-750 volts or communication circuits not supported on a messenger, or above communication or supply circuits which are supported on a messenger, provided the supply service drop unprotected conductors are at least 25 inches horizontally from the center line of a pole or are attached to suitable brackets (at least 25 inches from center line of pole) on each end of the clearance arm and carried on the underside of the clearances arm from end to end in fiber conduit or under wood protective covering.

The installation of service drops in accordance with this rule will not entail any change in the communication conductors supported on the pole.  (See App. G, Fig 40)

(3)    On Pole Top Extensions: Supply service drops 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 vertical conductor clearance less than 48 inches (Table 2, Case 8, Column D; Case 9 Column C) but not less than 2 feet provided the service drop conductors clear the center line of the pole (projected) not less than 25 inches horizontally, and also provided the service drop conductors clear the outside pin position conductors of the other circuit not less than 2 feet.  Where, in addition to the pole top bracket or extension, the supply service drop conductors are supported on a bracket on the end of the other line crossarm, a clearance of not less than 12 inches will be permitted at the points of crossing of line conductors in the outside pin positions.  In such construction the crossarm of the extension shall be of wood.  The installation of service drops in accordance with this rule will not entail any change in the communication conductors supported on the pole.  (See App. G, Fig 41.)

(4)    From Communication Service Drops: The radial clearance between supply service drop conductors may be less than 48 inches as specified in Table 2, Column C, Cases 4 and 9; Column D Cases 3 and 8, but shall be not less than 24 inches.  Where within 15 feet of the point attachment of either service drop on a building, this clearance may be further reduced but shall be not less than 12 inches.

(5)    Above Trolley Contact Conductors: Service drops may be installed above trolley contact conductors, including messenger in catenary construction, at a vertical distance of not less than 4 feet, provided the service drops clear the top of rails a vertical distance of not less than 26 feet where the railroad crossed transports standard freight cars, or not less than 23 feet where the railroad does not transport standard freight cars.  (See Rule 74.4-B1.)

(6)    From Conductors of 750-7500 Volts: Service drops may cross above or below line conductors of 750-7500 volts supported on the same pole at clearances less than specified in Table 2, Case 10, Column D, provided such drops shall be not less than 2 feet vertically and 1 foot horizontally from the supply line conductors.

D.    Clearance from other Poles

The clearance between service drop conductors and the center line of any pole not supporting them shall be not less than 22 ½ inches (Rule 32.3).  In case the pole involved in this clearance is within 10 feet of a pole supporting the service drop, this clearance may be less than 22 ½ inches but shall not less than 15 inches.

E.    Clearances From Conductors on Combination Arms

In Combination arm construction the following clearances are required between service drop conductors of 0-750 volts and the conductors of 750-7500:

(1)    6-Inch Minimum Pole Pin Position Separation:

Where Conductors of the two voltage classification are supported on opposite ends of a crossarm with a minimum horizontal separation of 36 inches between pole pin positions, service drops which run directly from such crossarm shall not cross conductors of the 750-7500 volt classification on the same arm.

(2)    42-Inch Minimum Pole Pin Position Separation:

a)    Service from Line Arms:  Where conductors of the two voltage classifications are supported on opposite ends of the crossarm with a minimum horizontal separation of 42 inches between pole pin positions, service drops may be run directly from the 0-750 volt portion of a line arm and may cross below conductors of 750-7500 volts on the same arm.  Under these conditions the vertical separation at the point of crossing shall be not less than 6 feet radially from the center line of pole.

b)    Services from Buck Arms: Where conductors of the two voltage classifications are supported on opposite ends of the buck arm with a minimum horizontal separation of 42 inches between pole pin positions and not less than 2 feet vertical separation between line arm conductor level and buck arms or service buck arms, provided:

Such service drops shall clear conductors of 750-7500 volts by not less than 2 feet vertically at the point of crossing;

Such service drops shall not pass through the climbing space specified in Rule 54.7-A3c;

Such service drops shall not cross under the 750-7500 volt end of the line arm within the third pin position; and

Where such service drops are run from double buck arms, or from single buck arms installed on the side of the pole below the 750-7500 volt portion of related line arm, the pole position on the 750-7500 volt end of the line arm shall be left vacant.

F.    From Racks

Service drops may be run directly from low voltage racks on poles.  Where multiple conductor service cable is used, the cable grip shall be attached to the neutral insulator of the rack on the pole or suitable insulation shall be used between the point of attachment on the rack or pole and the surface of the cable, except where the rack hardware is effectively grounded through the medium of a metal pole.