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 MIL-HDBK-419A
ELECTROMAGNETIC INTERFERENCE (EMI) -- Any electrical or electromagnetic phenomenon, manmade or
natural, either radiated or conducted, that results in unintentional and undesirable responses from, or
performance degradation or malfunction of, electronic equipment.
ELECTROMAGNETIC PULSE (EMP) -- A large impulsive type electromagnetic wave generated by nuclear or
chemical explosions.
EQUIPMENT, UNIT OR PIECE OF -- An item having a complete function apart from being a component of a
system.
EQUIPMENT GROUNDING -- Attained by the grounding conductor of the fault protection subsystem, and/or
bonding to the signal reference subsystem or the structural steel elements of the building.
EQUIPOTENTIAL PLANE -- A grid, sheet, mass, or masses of conducting material which, when bonded
together, offers a negligible impedance to current flow. (serves as signal reference subsystem for new
facilities)
FACILITY -- A building or other structure, either fixed or transportable in nature, with its utilities, ground
networks, and electrical supporting structures. All wiring, cabling as well as electrical and electronic
equipments are also part of the facility.
FACILITY GROUND SYSTEM -- The electrically interconnected system of conductors and conductive
elements that provides multiple current paths to earth. The facility ground system includes the earth electrode
subsystem, lightning protection subsystem, signal reference subsystem, fault protection subsystem, as well as
the building structure, equipment racks, cabinets, conduit, junction boxes, raceways, duct work, pipes, and other
normally noncurrent- carrying metal elements.
FAR FIELD -- The region of the field of an antenna where the radiation field predominates and where the
angular field distribution is essentially independent of the distance from the antenna.
FAULT -- An unintentional short-circuit, or partial short-circuit, (usually of a power circuit) between
energized conductors or between an energized conductor and ground.
FIRST SERVICE DISCONNECT -- The necessary equipment (circuit breakers, switches, fuses etc.) located at
the point of entrance of power conductors to a building or other structure.
GROUND -- The electrical connection to earth primarily through an earth electrode subsystem. This
connection is extended throughout the facility via the facility ground system consisting of the signal reference
subsystem, the fault protection subsystem, the lightning protection subsystem and the earth electrode
subsystem.
GROUNDED CONDUCTOR -- (Neutral) The circuit conductor that is intentionally grounded (at first service
disconnect or power source).
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