Quantcast Earth Electrode Subsystem

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 


MIL-HDBK-419A
1.13 INSPECTION AND TEST PROCEDURES FOR A NEW FACILITY. The grounding, bonding, and shielding
practices and procedures recommended in this chapter should be implemented as integral elements of the
facility during the construction of the building or structure. To ensure that the implementation is accomplished
in a timely manner, the construction efforts should be carefully monitored from the onset of excavation through
completion of the facility. Prior to acceptance of the facility, complete the Facility Checkout Form provided
in Section 1.13.6. The following guidelines are provided to aid in the inspection and checkout of the facility.
1.13.1 Earth Electrode Subsystem.
Observe installation procedures. Specifically see that the recommendations of Section 1.2.4 are
a.
observed. Verify that ground rods conforming to the sizes specified in MIL-STD-188-124A are used. If the
ground rods are driven in place, see that driving collars or nuts are used to prevent damage to the rods. Watch
for bent and broken or bulged couplings between sections. Seriously weakened or damaged couplings should be
replaced before driven below grade.
Spot check the resistance of rods as they are driven. Use the fall-of-potential method described in
b.
Section 2.2.2.2.1 to determine the resistance of a rod when it reaches the design or specified depth. With the
aid of Figures l-4, l-5, and l-6, project the net resistance of the total number of ground rods. This projection
should indicate if the planned electrode subsystem will achieve 10 ohms (or less) resistance. As additional rods
are driven, continue to spot check the resistance of individual rods by measuring the resistance at each
successive fourth or fifth rod. This procedure will permit a decision to be made on the necessity for adjusting
the electrode configuration (either adding to or subtracting from) to achieve the required resistance (see
Section 1.2.2.3).
c.
See that cable interconnecting the rods is of a correct size (1/0 AWG). Inspect all connections
between cable sections and all interconnections between cable and ground rods. All connections to be buried
and subsequently made inaccessible must be welded or brazed. Restrict the use of clamps or bolted connections
to locations which will remain accessible.
d.
Check to see that provisions are made for interconnecting the earth electrode subsystem with metal
utility lines, buried tanks, and other underground metals.
e.
Verify that risers or cables of appropriate size are installed for lightning down conductor, signal
ground, and power system ground connections (see Section 1.3.2.2). Ensure that risers used for lightning down
conductors are not used as part of the signal reference or fault protection subsystems.
f.
Once the complete minimum system is installed, measure the resistance to earth for the system
using the fall-of-potential method described in Section 2.2.2.2.1. If the resistance is greater than 10 ohms,
alternate methods described in Section 2.9 of Volume I for reducing the resistance-to-earth shall be considered.
Insure that all changes or modifications are properly indicated on the facility drawings.
g.
1-193





 


Privacy Statement - Copyright Information. - Contact Us

Integrated Publishing, Inc.