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 MIL-HDBK-419A
1.6 BONDING, SHIELDING, AND GROUNDING RELATIONSHIP.
a . The simple grounding of elements of a communications facility is only one of several measures
necessary to achieve a desired level of protection and electrical noise suppression. To provide a low-impedance
path for (1) the flow of ac electrical current to/from the equipment and (2) the achievement of an effective
grounding system, various conductors, electrodes, equipment, and other metallic objects must be joined or
bonded together. Each of these bonds should be made so that the mechanical and electrical properties of the
path are determined by the connected members and not by the interconnection junction. Further, the joint
must maintain its properties over an extended period of time, to prevent progressive degradation of the degree
of performance initially established by the interconnection. Bonding is concerned with those techniques and
procedures necessary to achieve a mechanically strong, low-impedance interconnection between metal objects
and to prevent the path thus established from subsequent deterioration through corrosion or mechanical
looseness.
The ability of an electrical shield to drain off induced electrical charges and to carry sufficient
b.
out-of-phase current to cancel the effects of an interfering field is dependent upon the shielding material and
the manner in which it is installed. Shielding of sensitive electrical circuits is an essential protective measure
to obtain reliable operation in a cluttered electromagnetic environment. Solid, mesh, foil, or stranded
coverings of lead, aluminum, copper, iron, and other metals are used in communications facilities, equipment,
and conductors to obtain shielding. These shields are not fully effective unless proper bonding and grounding
techniques are employed during installation. Shielding effectiveness of an equipment or subassembly enclosure
depends upon such considerations as the frequency of the interfering signal, the characteristics of the shielding
material, and the number and shapes of irregularities (openings) in the shield.
1.7 GROUNDING SAFETY PRACTICES.
a . It is essential that all personnel working with Communications-Electronics (C-E) equipment and
supporting systems and facilities strictly observe the rules, procedures, and precautions applicable to the safe
installation, operation, and repair of equipment and facilities. All personnel must be constantly alert to the
potential hazards and dangers presented and take all measures possible to reduce or eliminate accidents.
b . Safety precautions in the form of precisely worded and illustrated danger or warning signs shall be
prominently posted in conspicuous places, to prevent personnel from making accidental contact with
high-voltage sources such as power lines, antennas, power supplies, or other places where uninsulated contacts
present the danger of electrical shock or short circuits. Signs shall also warn of the dangers of all forms of
radiation hazards, acids, and chemical inhalation, plus all other potential sources of personnel danger. Power
cutoff features built into the equipment must be used in strict adherence to the intended use.
c . During the installation of equipment, warning tags are used to note the existence of potential danger
when individual circuits or stages are being checked out. The tags should contain appropriate information to
alert all personnel of the dangers involved and specific restrictions as to the use of the equipment. The
equipment being installed shall be appropriately tagged in accordance with the directives of the local safety
officer, equipment manufacturer, or other responsible agent.
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