MIL-HDBK-1191
10.3.18
ALTERNATE SOURCE TESTING. Alternate power source emergency
systems shall be tested before final acceptance, for proper operation, as
required by NFPA 99 and 110. All connected loads will be made operational,
and will be operating within normal demand load tolerances. Alternate systems
will be designed to facilitate periodic system-wide and component test and
inspection.
INTERIOR ELECTRICAL SYSTEMS. Interior electrical systems shall
10.4
conform to NFPA codes except where military departmental criteria are more
stringent.
UTILIZATION VOLTAGE. 480Y/277V, 460V, 208Y/120V, 240V and 120V
10.4.1
low voltages and 4.16kV and 6.9kV medium voltages are common utilization
voltages found at military installations. However, 480Y/277 volt and 208Y/120
volt are the standard utilization voltages for new and existing medical
facilities.
INTERIOR DISTRIBUTION. Interior lighting and power loads will be
10.4.1.1
served at the highest voltage practicable. Fluorescent and high intensity
discharge (HID) lighting systems and building power loads will be supplied by
a 480Y/277 volt system. Dry-type transformers will be utilized to furnish
208Y/120 volt power for incandescent lighting, receptacle, and small equipment
loads. These transformers will be "K" factor rated if required for specific
non-linear loads (See sample analysis matrix Table 10-4). Where transformer
type voltage regulators are used to maintain nominal voltage within plus or
minus 5%; an automatic step or induction transformer regulator shall be used
which have adjustable high and low voltage limit controls and a voltage meter.
A 208Y/120 volt system will be provided where the use of higher voltage is not
cost effective. Main distribution switchgear and switchboards will be the
draw-out, solid state, adjustable trip circuit breaker. Panelboards for
branch circuits will be of the circuit breaker type. Ground fault protection
will be provided in accordance with NFPA-70 and 99. All protective devices
will be coordinated for selective overload, short-circuit, and ground fault
protection. Ground fault protection of the essential electrical system will
be as required above.
10.4.1.2
COORDINATION AND SHORT-CIRCUIT SYSTEM ANALYSIS.
Short-circuit and protective devices coordination studies will be in
accordance with TM 5-811-14. Additionally, a coordinated protective devices
setting will be provided by the designer. Selection of protective devices and
switchgear for a new electrical system shall be based on a short-circuit
protective device coordination analysis. For additions or modifications to
existing system, the analysis shall include all of the protective devices
affected in the existing system. All protective devices
shall be properly coordinated to provide selective tripping. No, series rated
protective equipment and/or devices will be allowed! Surge protection should
also be incorporated in the coordination analysis.
LOCATION AND SPACE REQUIREMENTS. Electrical equipment rooms will
10.4.1.3
be located at or near the building exterior to facilitate initial installation
of large equipment, and removal and replacement of defective equipment.
Adequate space will be provided for maintenance of electrical equipment and
equipment removal. Pipes and other equipment foreign to the electrical
equipment will not be located in, enter, or pass through such spaces or rooms.
Where practicable in finished areas of hospitals, panelboards, signal and
communication cabinets will be grouped, surface-mounted, in separate
electrical and communication ventilated wiring closets. Joint use closets are
not acceptable and will not be provided. Closets in which dry-type
transformers and automatic transformer type regulators are installed, should
be located away from noise sensitive areas and provided with adequate
ventilation to maintain an ambient temperature not to exceed 86 degrees F.
For hospitals with more than three floors, electrical and communication
closets should be stacked vertically whenever practicable. Panelboards in
critical care areas will be located in the vicinity of their loads, and will
10-14
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