A. Locate and arrange grouped cables in accordance with Data Sheet 5-31, Cables and Bus Bars. Provide a minimum vertical separation of 18 in. (46 cm) between stacked cable trays.
B. Locate cable trays so as to avoid or reduce exposures from oil piping as far as practical. Where separation is not possible, locate trays above adjacent oil piping and away from potential three-dimensional spill fires so trays do not provide channels to spread burning oil.
C. Locate power cables above trays containing control and instrumentation cables.
D. Seal openings in floors, walls, and ceilings through which cables and piping pass from one fire area to another with an FMApproved fire-stop of 1-hour fire resistance. Pay special attention to penetrations into the control room, relay room, and cable spreading room.
E. Keep combustible material out of cable trays. Use covers to protect exposed cable trays where accumulation of combustible material is possible.
F. Provide a fire-resistive barrier below the bottom tray where cable trays are exposed from oil fires below. This barrier, in addition to automatic sprinkler protection, will limit fire damage to cables.