Duct Bank Spacing

60-308 Separation from other conductors  (1) The conductors of an electrical communication system in a building shall be separated at least 50 mm from any insulated conductor of a Class 1 circuit or an electric light or power system operating at 300 V or less, and shall be separated at least 600 mm from any insulated conductor or an electric light or power system operating at more than 300 V, unless (a) one system is in grounded metal raceways, metal-sheathed cable, or grounded armoured cable; (b) the Class 1 circuit or electric light or power system operating at 300 V or less utilizes a hard-usage or extra-hard-usage flexible cord selected in accordance with Rule 4-012(1); or (c) both systems are permanently separated by a continuous, firmly fixed non-metal raceway in addition to the insulation of the conductors.

60-602 Underground raceway
Where communication conductors or cable assemblies are placed in underground raceway systems
(a) the raceway, including laterals, shall be separated from those used for the electric power system by not less
than 50 mm of concrete or 300 mm of well-tamped earth;