ERICO Practical Guide to Electrical Grounding - Manual (Page 117)

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With the perimeter conductor one meter outside the fence,
a worker standing inside the fence will have an increase in
touch potential, but only by about 10%. If the fence is not
connected to the main grid (Fig. 6-47), the following
must be considered:
1. Could an energized line fall on the fence?
2. Could other hazardous potentials exist during other
types of faults?
3. Can the fence be completely isolated from the main
grid at all times, including future expansions?
Fence grounding specifications. Some ground
only the fence fabric, others only the fence post. Some
continue the conductor up and ground the top rail while
others ground the top barbed wire.
The National Electrical Safety Code (NESC), ANSI C2-
1997, states (Rule 92E) that where substation fences are
required to be grounded they shall be designed to limit
touch, step and transferred voltages in accordance with
industry practices. When the fence posts are constructed of
conducting materials the grounding conductor shall be
connected to the fence posts with suitable connectors.
When the posts are made of a non-conductive material, the
fence barbed wire or mesh strands shall be bonded at each
grounding conductor point. (Fig. 6-49) The NESC also
requires that fences be grounded on each side of a gate or
similar opening and the gate shall be bonded to the
grounding conductor, jumper or fence. ERICO offers a
complete line of factory-made flexible bonding jumpers
and clamps for use with just about any fence. In addition,
all conductive gates shall be bonded across the opening by
a buried conductor. (Fig 6-50)
A second conductor, although not required by NESC, offers
personnel protection if installed under the swing area of the
gates as shown in (Fig. 6-50). It is also common practice to
connect the ground conductor to each corner post and to
line posts every 50 feet. Rolling gates can be bonded to the
gate post as shown in Figure 6-51.
Chapter 6: Special Grounding Situations
Fig. 6-48
Perimeter Conductor
Fence
Grid
Grid
Fig. 6-49
Splitbolt (Typ.)
Fig. 6-50
CADWELD Type VS
Welding Cable
CADWELD
Type HS
Cable Post Connection Gate Connection
Mold* W/M Sleeve Mold* W/M Sleeve
1/0 W.C. VSC2E-PS #90 54292E16 HSC2E-PS #90 S429E16
2/0 W.C. VSC2J-PS #90 S4292J16 HSC2J-PS #90 S4292J16
4/0 W.C. VSC2S-PS #115 S4292S16 HSC2S-PS #115 S4292S16
*Add Pipe Size (P.S.)
Rolling Gate Bonding
Fig. 6-51
Grounding Book 4/14/99 10/5/99 6:02 PM Page 109 (Black plate)