Earthing question
Earthing question
(OP)
I have come across an earthing design (see attached) where the earthgrid does not cover the complete substation surface area. A reason I was given is that the uncovered area is not frequented by people. I am no earthing guru and so would like some opinions on the following:
I have drawn a person who I believe may experience a touch voltage should an EF occur and the person is touching the fence as shown. The pink/black line is meant to show the approximate voltage gradient. Note that the section of fence being touch is electrically isolated from the rest of the fence.
Is there any merit to my concern?
Thanks.
I have drawn a person who I believe may experience a touch voltage should an EF occur and the person is touching the fence as shown. The pink/black line is meant to show the approximate voltage gradient. Note that the section of fence being touch is electrically isolated from the rest of the fence.
Is there any merit to my concern?
Thanks.






RE: Earthing question
RE: Earthing question
or indirect with the grounded grid. I think the fence has to be "isolated" and well "insulated". The posts have to
be also insulated and a 0.08–0.15 m (3–6 in) layer of high resistivity material, such as gravel, has to be spread 1m before
and after the fence.
RE: Earthing question
36-312 Grounding of metallic fence enclosures of outdoor stations
(1) The fence shall be located at least 1 m inside the perimeter of the station ground electrode area.
(2) The station ground electrode shall be connected to the fence by a tap conductor at each end post, corner
post, and gate post, and at intermediate posts at intervals not exceeding 12 m by a conductor of not less
than No. 2/0 AWG copper.
(3) The tap conductor at each hinge gate post shall be clamped or bonded to the gate frame by a copper braid
or a flexible copper conductor of at least No. 2/0 AWG.
(4) The tap conductor shall be connected to the fence post, the bottom tension wire, the fence fabric (for
which the conductor may be woven in at least two places), the top rail, and each strand of barbed wire,
with the connection to the bottom tension wire, the fence fabric, and barbed wire strands made with
bolted or equivalent connectors, and with the top rail connections bonded at every joint by a jumper
equivalent to No. 2/0 AWG copper.
(5) When there is a metal boundary fence in proximity to the station fence, the touch voltages within 1 m of
all parts of the boundary fence shall not exceed the tolerable values specified in Table 52.
Bill
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"Why not the best?"
Jimmy Carter
RE: Earthing question
Thanks and regards.