Custom Search
|
|
|
||
 MIL-HDBK-419A
The equipotential plane may be installed on the floor under tile or carpet. If this is impractical, the
equipotential plane may be installed overhead but every consideration should be given to placing it on or in the
floor. In some cases it may be installed under the floor with ground risers penetrating the floor to the
equipments installed above. Figure 2-15 is an example of the plane installed overhead.
protection networks in a new facility or in an existing facility can rapidly deteriorate unless adequate and
thorough maintenance is performed at regular intervals throughout the life of the facility.
2.3.1 Schedules and Records.
In a new facility, consider the initial checkout (see Section 1.13) as the first maintenance inspection for the
facility. Utilize the results or information provided by the initial facility inspection as a base or starting point
of comparison of the results of subsequent inspections. Subsequent inspections should be performed at least
annually. In addition, a thorough inspection should be performed on affected parts or elements of the networks
following major changes or additions to the facility either of the structure itself or of the equipment or systems
located in the structure.
In an older facility, consider the survey (if performed) described in Section 2.2 as the initial maintenance
inspection. If a survey has not been made, an initial inspection of the facility should be made to determine the
general condition of grounding networks, bonds, shields, and lightning protection subsystems. Subsequent to the
survey or initial inspection, a maintenance inspection should be conducted annually and after major changes or
additions to the facility as discussed above.
Chronological records of all tests and observations should be maintained. When a significant departure from the
record is noted, an investigation should be performed to determine the cause and the necessary corrective
action taken. Any measurement (i.e., earth electrode subsystem resistance, bond resistance, point-to-point
ground network resistance, etc.) not meeting the specified or recommended value should be immediately
investigated to see if rework is desired.
2.3.2 Maintenance Procedures. Maintenance procedures for the earth electrode subsystem, lightning
protection subsystem, signal reference subsystem, fault protection subsystem, facility ground system, bonding,
and shielding are presented in Sections 2.3.2.1 through 2.3.2.6. Upon completion of any or all of these
procedures, prepare the Facility Maintenance Report of Section 2.3.3 and place it in the permanent
maintenance file or record along with other supporting evidence such as test results, photographs, and drawings.
Where deficiencies are noted that are immediately correctable (e.g., broken or misplaced bond wires or
jumpers, loose bolts or screws, or other minor defects), they should be corrected with appropriate notation
made on the Facility Maintenance Report. A Major Discrepancy Report (illustrated in Figure 2-16) should be
made out on major deficiencies (e.g., earth electrode resistance too high, parts of structure outside the cone of
protection, excessive current levels on signal ground conductors, etc.) to identify those areas needing
significant rework or upgrading. (Do not confuse rework or upgrading associated with normal maintenance
activity with a total facility rework or upgrading as described in Section 2.2 unless the facility has degraded to
the point where a major overhaul is necessary for minimal performance or acceptability.)
2-36
|
 
|
|
|
||
