GE Mark VIe System Manual page 146

6.6.2.1 General Practices
The following general practices should be used for all levels of cabling:
• All cables of like signal levels and power levels must be grouped together in like cableways.
• In general, different levels must run in separate cableways, as defined in the different levels. Intermixing cannot be
allowed, except as noted by exception.
• Interconnecting wire runs should carry a level designation.
• If wires are the same level and same type signal, group those wires from one cabinet to any one specific location together
in multiconductor cables.
• When unlike signals must cross in trays or conduit, cross them in 90° angles at maximum spacing. Where it is not
possible to maintain spacing, place a grounded steel barrier between unlike levels at the crossover point.
• When entering terminal equipment where it is difficult to maintain the specific spacing guidelines displayed in the
following tables, keep parallel runs to a minimum, not to exceed 1.5 m (5 ft) in the overall run.
• Where the tables display tray or conduit spacing as 0, the levels can be run together. Spacing for other levels must be
based on the worst condition.
• Trays for all levels should be solidly grounded with good ground continuity. Conduit should provide shielding.
The following general practices should be used for specific levels of cabling:
• When separate trays are impractical, levels L and M can be combined in a common tray if a grounded steel barrier
separates levels. This practice is not as effective as tray separation, and may require some rerouting at system startup. If
levels L and M are run side-by-side, a 50 mm (1.97 in) minimum spacing is recommended.
• Locate levels L and M trays and conduit closest to the control cabinets.
• Trays containing level L and level M wiring should have solid galvanized steel bottoms and sides and be covered to
provide complete shielding. There must be positive and continuous cover contact to side rails to avoid high-reluctance air
gaps, which impair shielding.
• Trays containing levels other than L and M wiring can have ventilation slots or louvers.
• Trays and conduit containing levels L, M, and H(S) should not be routed parallel to high power equipment enclosures of
100 kV and larger at a spacing of less than 1.5 m (5 ft) for trays, and 750 mm (2.5 ft) for conduit.
• Level H and H(S) can be combined in the same tray or conduit but cannot be combined in the same cable.
• Level H(S) is listed only for information since many customers want to isolate unfused high voltage potential wires.
• Do not run levels H and H(S) in the same conduit as level P.
• Where practical for level P and/or P(S) wiring, route the complete power circuit between equipment in the same tray or
conduit. This minimizes the possibility of power and control circuits encircling each other.
146 GEH-6721_Vol_I_BP GEH-6721_Vol_I Mark VIe and Mark VIeS Control Systems Volume I
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