3.12 The Layout of Cables in the Bureau
3.12.1 Outer conductors of coaxial feeder cables and two ends of shielding layers of shielded cables in bureaus shall keep good electrical contact with external surfaces of metal equipment enclosure of connected devices or chassis equipment.
3.12.2 If telecommunication bureaus(stations)are at susceptible areas of lightning harm or near to the interference source of high electromagnetic field,the metal conduits shall be adopted for laying of cable inside equipment rooms.
3.12.3 When the length of various signal data lines at telecommunication bureaus(stations)is larger than 30m,such data lines shall run through metal conduits or cables with shielding layer shall be used.Two ends of metal conduits or shielding layers of cables shall be welded with the nearby voltage balancing nets or earth grids at the same floor.