Section 5:
INSTALLATION OF DISTRIBUTION SYSTEM
5.1
Overhead Method
5.1.1
General.
For details of overhead line design, refer to DM-4.2.
5.1.2
Limitations.
The use of overhead lines shall be avoided in the
following locations:
a) Electronics Facilities - For clearances of overhead electric
power lines from electronics facilities, refer to DM-12.1.
b) Airfields - The installation of overhead lines in airfield
clearance zones shall be avoided entirely. Regulations are imposed by the
Federal Aviation Administration and Naval Air Systems Command.
c) Loading Areas - Piers and loading areas where overhead cranes
operate shall be clear of aerial electric powerlines.
d) Industrial Areas - Congested industrial areas shall be clear of
aerial lines. Requirements for ammunition storage areas are given in MIL-
HDBK-1004/6, Lightning Protection. In addition, NAVSEA OP-5, Ammunition
and Explosives Ashore, delineates restrictions concerning overhead line
service for magazine facilities.
5.2
Underground Method. If average conditions prevail, underground
construction and maintenance is more expensive than overhead installation.
Applications shall be limited to cases in which other factors besides
economics dictate. Examples of such factors have been indicated in
para. 5.1.2.
5.2.1
Applications. Underground electric power distribution systems are
normally more resistant to damage from severe atmospheric disturbances,
traffic, and simple forms of sabotage than overhead systems.
5.2.2
Expansibility. Growth is a factor of extreme importance in the
design of underground electric power systems. Spare capacity, as well as
provisions for the future crossing of roadways, runways, and taxiways, shall
be included in the design. Refer to MIL-HDBK-1004/2, Power Distribution
Systems, for details of underground construction design and criteria for
selection of draw-in or direct-burial systems.
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