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General Order 64-A

 

Section VIII

 

Detailed Construction Requirements For Communication Lines

(Class C Circuits)

 

87.4    Clearances.

 

A.    General.

The clearances specified in Tables 1 and 2 for conductors apply except where modified herein.

 

B.    Between Conductors.

 

(1)    Cable Conductors:  Properly insulated cables, duplex, triplex and paired conductors whether single or grouped, are considered single conductors and therefore no clearance is required between the conductors which comprise them.  The clearances of Table 2, Case 15 do not apply in this instance, nor do they apply to wires of the same phase or polarity between which there is no difference of potential.

 

(2)    Attached Directly to Poles:  Cables attached directly to poles (which carry no cross arms) are not restricted in the use of the top 3 feet of the pole; below this point cables may be attached to poles at intervals of not less than 12 inch vertical separation.  (See App. G, Fig. 84.)

A minimum vertical clearance of 2 feet between cables attached directly to poles and circuits carried on cross arms shall be maintained where said cables occupy both sides of the pole.

 

C.    Between Cables and Messengers.

Cables supported by messengers are not required to be any specified distance from the messenger.  Table 2, Case 1, does not apply in this instance, nor does it apply where messengers of one system intersect, branch or cross.

 

D.    From Poles.

 

(1)    Center Line: Cables supported by crossarms shall clear the center line of the pole the distance prescribed for exchange circuits or toll circuits, depending on the line classification.  (See Rule 84.4-D.)

 

(2)    Surface:  Cables attached directly to either or both sides of poles may be maintained at less than 3 inches from the surface thereof.

 

E.    Above Trolley Contact Conductors.

Cables and messengers which are suitably protected may have a clearance of not less than 4 feet above the trolley contact conductors, providing they meet the requirements of Rule 84.4-B1a.

 

F.    From and Above Buildings, and Other Structures.

The normal minimum clearance of cables from surface of buildings, etc., is given in Table 1, Case 8.

Communication cables are not required to clear sides of buildings or other structures any specified distance, but they shall be installed so that they do not interfere with the free use of fire-escapes, exits, etc.  Nothing herein shall prohibit the attachment of such cables to buildings provided they are installed in accordance with the safety orders of the Industrial Accident Commission.

The vertical clearance of 8 feet between communication cables and buildings (Table 1, Case 6, Column B) may be reduced to 2 feet under the following conditions.

 

Over roofs of pitch (26 from the horizontal) or greater.

Over buildings where the horizontal overhang does not exceed 2 feet.