15 August 2002
. Buildings housing either tanks
or generators should
of light steel construction and located at least 15.24 m (50 ft) from any adjacent
structure or operation.
Electrical Conduits. Keep electrical circuits separate from service piping.
They may be placed in concrete encased ducts behind the dock wall or, for large
drydocks, in a separate tunnel shoreward from the pipe tunnel or gallery. Secondary
electric power distribution lines are sometimes placed in supplementary utility tunnels,
separate from immediate drydock outlet system.
Support. Wherever electric cables in underground installations are
mounted on wall racks, support the cables away from the wall to allow leakage water to
Substations. One or more electrical substations are required to provide
for conversion and distribution of electricity at the required voltages and capacities for
ship services, and for operation of dock supporting facilities. Use mobile or portable
transformer units to supply occasional high demand loads, and for testing nuclear
vessels. Provide suitable protected primary feeder terminations at appropriate locations
for portable design guidance. Mobile or portable transformer units should have a
primary fused switch and a secondary panelboard with circuit breaker protection, and
suitable numbers of 3-pole 400-ampere receptacles mounted on the transformer unit.
Two feeders should be run to the pumphouse, in the event that the main
feeder goes down. They should be fed from two separate power sources.
Install a back-up emergency diesel generator near each pumphouse to
run at least the drainage pumps and alarms in the event all electrical power is lost.
Design. A single substation may be incorporated into the pumpwell
machinery room or, for a large drydock, one may be required on each side of the
drydock, and not necessarily in the pumpwell machinery room.
Power Service Outlets. Power must be conducted from the substation to
dockside capstans, lights, and other necessary outlets, through cables in ducts run from
manhole to manhole. The outlets should be weathertight and above mean high water.
Make provision for draining this secondary underground electric distribution system.
Refer to MIL-HDBK-1025/2 Dockside Utilities criteria for outlets for ship services and
portable equipment, and recommended design of electrical distribution systems.
Power Uses. Electric power is required for the following:
Sluice gates and valves.