fence post ground tabs

Tony S

Senior Member
Not really much use as I’m on the wrong side of the pond.

We would run earth bonds to the perimeter fence of substations. The fence would be of all bolted construction and so electrically continuous. All well and good until someone decided they had a better use for the copper tape and stole it from all our remote substations.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
substations
figured as much. done a lot of them. cadweld 2/0 tails onto
them, and T weld the tails to a 4/0 buried 18" down in the dirt.

if anyone had such a thing, LADWP would'a figured it out by now.
they spend a lot of time cadwelding poles.
 

winnie

Senior Member
You don't need to ground the fence post.

You need to bond them with all of the other 'grounded' components, eg. equi-potential bonding grid, ground rings, etc.

At a substation during a fault, step potential can be a serious issue, so lots of 'grounded' components are subject to pretty serious bonding connections.

-Jon
 

Ingenieur

Senior Member
why would one need to "ground" a fence post that is already in the ground?
as noted step and touch potential
assume a fault of 20 ka with station bed connected to xo
station ground mat 2 Ohm
fence 10 Ohm (not bonded)
total thru fence to xo = fence + mat = 12
station i 17.15 ka + 2.85 from fence = 20 ka
fence i alone 2.85 ka

v station ~ 2 x 20 = 40 kv
v fence ~ 10 x 2.35 = 23.5 kv

touch potential fence to station mat = 40 - 23.5 = 17.5 kv, 17.5 A thru avg person
if you bond fence to station > 0
 

petersonra

Senior Member
You don't need to ground the fence post.

You need to bond them with all of the other 'grounded' components, eg. equi-potential bonding grid, ground rings, etc.

At a substation during a fault, step potential can be a serious issue, so lots of 'grounded' components are subject to pretty serious bonding connections.

-Jon
That makes sense.
 

Wire-Smith

Senior Member
figured as much. done a lot of them. cadweld 2/0 tails onto
them, and T weld the tails to a 4/0 buried 18" down in the dirt.

if anyone had such a thing, LADWP would'a figured it out by now.
they spend a lot of time cadwelding poles.

the only thing i don't like about cadwelding in this instance is the post will corrode from the inside out a lot quicker after welding on it after galvanizing, if you could get a tab put on before galvanizing it would be a little more robust system. obviously i can have a fabricator make some and have them galvanized but it would likely be cheaper if a manufacturer already does it, but i can't find any.

also has anyone ever torqued a ground(bonding clamp (ground clamp is just trade name)) clamp to a gate, sometimes the gate member smashes a ton and you can't get to the torque.
 
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