Custom Search
|
|
|
||
 MIL-HDBK-419-A
1.12 FENCES.
1.12.1 Introduction. Perimeter or security fences designed as part of a facility's ground system shall be
constructed of galvanized steel chain-link fencing; vinyl-coating shall not be used. The supporting post and top
rails or wire shall be electrically conductive materials. A #6 AWG (minimum) copper conductor, called a
reinforcing wire shall be woven through the entire length of the fence. Both the fence post and the fence
reinforcing wire shall be grounded periodically to ground rods. A suitable interval for the ground rods is
100 feet for small sites and 500 feet for large sites. Installation will be shown on Figure l-101.
1.12.2 Grounding. Fences should be grounded on each side of every gate and, where crossed by high tension
lines, at points 150 feet on each side of high tension crossing. If a fence consists of wooden post and horizontal
metal strands only, down conductors should be run the full height of the fence post and securely fastened to
each wire so as to be electrically continuous. The connection to the ground may be made at the post, if the
post is metal and is electrically continuous with the fence.
1.12.3 Installation. Installation of fence grounds shall be accomplished as follows:
a.
Thread a bare conductor, #6 AWG or larger, through individual links of the fence. This must be
accomplished by threading two or three links at a time and pulling the conductor through until all slack has been
removed; then repeat the process. The copper wire shall be continuous between posts. Splices, if required,
shall be made at fence post bonds.
b.
Prepare bonding surface in accordance with Section 1.7.2.
c.
Bond reinforcing wires at each post with exothermic welds or by brazing.
d.
Bond ground straps to fence posts with exothermic welds or by brazing. Bonds to ground rods shall
be exothermic welds or clamped and brazed.
Seal all bonding surfaces in accordance with Section 1.7.3.
e.
1-191
|
 
|
|
|
||
