MIL-HDBK-1191
be accessible to the operating staff only.
Such panelboards will not be
located in the patient bedrooms.
A minimum of one branch circuit electrical
10.4.1.4
ELECTRICAL ROOMS.
room shall be provided for each smoke zone of a hospital building space, and
each 22,500 square feet (2025 square meter) of other medical facilities
building space. The footprint for each piece of equipment with working space,
and NFPA-70 clearance requirements shall be shown. No branch circuit
electrical room will feed loads beyond the smoke zone in which it is located.
The branch circuit electrical rooms will be accessed off of a primary through
corridor, and the entry door or doors will swing 180 degrees as not to impede
traffic flow in the corridor or violate clearance requirements of NFPA-70. In
multi-story medical facilities, the branch circuit electrical rooms should be
stacked. A minimum of 20 percent additional free wall space should be provided
to accommodate customer flexibility requirements.
CONDUIT, CABLE TRAY AND WIRE. All wiring will be insulated copper
10.4.2
in conduits and installed per NFPA-70 and MIL-HDBK 1190. Metal enclosed
feeder, plug-in busways or surface metal raceway may be used. A green
insulated copper ground conductor will be run with all branch circuits. Wiring
in all patient care areas and the life safety branch and critical branch of
the essential electrical system will consist of insulated conductors installed
in a separate metallic raceway. Where cable trays are used the normal and
emergency power conductors will be in separate compartments. Cable and raceway
circuit identification shall be at each end and at all transitions.
10.4.2.1
Conductors installed to furnish emergency power will not be
installed in the same raceway with normal power conductors.
10.4.2.2
All normal and emergency power junction boxes, pull boxes and
similar parts will be readily accessible. Clearly identified access panels
will be installed as necessary for proper maintenance and operation of the
electrical distribution system.
BRANCH CIRCUITS. All circuits serving patient care areas shall
10.4.3
comply with NFPA-99 and 70 except where reference criteria requires more
stringent standards.
WET TREATMENT AREAS. Circuits serving "wet" treatment locations,
10.4.4
see subparagraph 10.4.7.9.a, "WET LOCATIONS," will be furnished with ground
fault interrupters. Ground fault interrupters on circuits serving life support
equipment will not be installed,as required by NFPA-99 and 70.
10.4.6
RADIOLOGY PROVISIONS.
X-RAY FEEDER. Radiographic or fluoroscopic equipment will be
10.4.6.1
supplied by a 3-phase, 5 wire neutral and ground, 480Y/277 volt feeder from
the main distribution switchboard to an enclosed circuit breaker disconnect
located adjacent to the associated X-ray control room. X-ray loads will not
be included in the demand load. Effect of X-ray unit momentary kVA load on
transformer voltage regulation will be evaluated. Transformer size will be
increased as necessary and feeders sized for satisfactory system performance.
Separate service transformers to the X-ray units will not be provided. A door
interlock system will be provided to prevent production of X-rays when any X-
ray room door is open. Magnetic type door switches, and conduit and wiring
from the switches to the control console will be provided. Doors immediately
adjacent to the control room may not be required to be part of the interlock
system. A single phase 120/208 volt branch circuit panelboard will be
provided in each room for X-ray unit peripheral equipment. Additional
electrical design requirements are contained in the (Universal) x-ray room
criteria portion of the Section Medical and Dental Equipment and Appendix "B".
MOBILE X-RAY UNIT OUTLETS. Mobile X-ray equipment in nursing
10.4.6.2
units will normally be battery operated. Duplex receptacles rated 20-ampere,
10-15
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