Original General Order 128

Section III

Requirements For Supply Systems

33.4    Clearances and Depths

The clearance between supply cables and other cables ducts pipes and structures independently installed shall be as great as practicable. The distance between the top of permanently installed supply cables and the surface under which they are installed shall be sufficient to reasonably protect the cables.

A.    Separation From Other Cables, Ducts, Pipes And Structures

(1)    From other supply cables.

a)    Independently Installed: Supply cables, when independently installed, shall be separated, where practicable, from other supply duct systems or buried cables or conductors by not less than 3 inches of concrete, 4 inches of brick masonry or 12 inches of earth.

b)    Concurrently Installed: Supply cables, when concurrently installed with other supply cables in duct, duct systems or buried cables or conductors, may be installed with less separation than required by Rule 33.4–A1a when the parties involved mutually agree. Cable installed in an existing duct shall be considered a concurrent installation.

(2)    From communication systems.

a)    Independently Installed: Supply cables, when independently installed, shall be separated, where practicable, from communication duct systems and buried cables or conductors by not less than 3 inches of concrete, 4 inches of brick masonry or 12 inches of earth.

b)    Concurrently Installed: Supply cables, when concurrently installed with communication duct systems and buried cables or conductors, may be installed with less separation than required by Rule 33.4–A2a when the parties involved mutually agree. Cable installed in an existing duct shall be considered a concurrent installation. (See Rules 41.4–B and 43.3–B )

(3)    From foreign substructures. (Except Communication Systems)

a)    Independently Installed: Supply cables, when independently installed, shall be separated where practicable, from gas, water, oil, or other pipe systems, or other foreign substructures, by a clearance of at least 12 inches when paralleling and by at least 6 inches when crossing.

b)    Concurrently Installed: Supply cables, when concurrently installed with gas, water, oil, or other pipe systems, or other foreign substructures, shall be installed with the separation required by Rule 33.4–A3a except that when the parties involved mutually agree, there may be less separation for supply cables of 0 - 750 volts. Cable installed in an existing duct shall be considered a concurrent installation.

B.    Depth Below Base Of Rail

The tops of all supply cables shall be located below the base of the lowest rail at a depth of not less than 30 inches, in the case of street railroads, and not less than 42 inches, in the case of other railroads.

Where these depths are not practicable, or for other reasons, this clearance may be reduced by agreement between the parties concerned. In no case, however, shall the tops of the supply cables extend higher than the bottom of the ballast section which is subject to working and cleaning.

C.    Depths

Supply cables shall be installed at a minimum depth below the surface under which they are located as follows except as provided in Rule 33.4-D.

(1)    Sidewalks, Parkways and Private Property (750 Volts or Less): 18 inches for supply cables that operate at a potential of 750 volts or less.

(2)    Thoroughfares (750 Volts or Less): 24 inches for supply cables that operate at a potential of 750 volts or less.

(3)    751 Volts to 35,000 Volts: 24 inches for supply cables that operate at potentials of 751 to 35,000 volts.

(4)    Above 35,000 Volts: 36 inches for supply cables that operate at potentials above 35,000 volts.

D.    EXCEPTIONS

(1)    Mechanical Protection: Lesser depths than those listed in Rule 33.4–C may be used where suitable mechanical protection is employed. Suitable mechanical protection shall consist of the following or their equivalents:

a)    Steel conduit or plastic pipe made of rigid unplasticized polyvinyl chloride having the properties and dimensions specified in Type II, High Impact, Normal Chemical Resistance in United States Commercial Standard No. CS 207-60 with a minimum wall thickness of 0.15 inches.

b)    A layer of concrete at least 3 inches in thickness above the cable or duct.

c)    Cable armor of No. 12 BWG steel wire closely wound or two layers of steel tape each 0.020 inches thick.

(2)    Terminations, Splices, or Other Points of Access: Lesser depths than those listed in Rule 33.4–C are permitted where cables and conductors rise for terminations or splices or where access is otherwise required.