Mains electric fence: grounding question

spookypony

spookypony

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So I've finally installed the mains fencer, yay! And the voltmeter is reading 7k all around (maximum it can show) so I assume it's properly zappy...but I'm a bit worried that my ground stake may be too close to an electrical pole (there's a line running over my place), which is also whence the mains go into my house.

Currently, the ground stake for the fence is about 10m away from the pole. How can I tell if it's too close? What would the consequences be? Will of course move it if needed, but would rather leave it where it is!
 
I would imagine the electricity company jump through all the safety hoops and then some, but why not call them, mention your concerns to the girl on the switch board and ask to speak to an engineer? I'm not sure I would want to rely on advice from a horsey forum if I felt there was any danger! :D

And I wouldn't hesitate to phone them if I wanted to know. I do that sort of thing quite often and the technician I have ended up speaking to is usually grateful for the diverson and change from routine.
 
Good advice, thank you! Will do that tomorrow! :)

In the meantime, anyone know how I can find out where the house itself is grounded? And any advice on testing the earthing of the fence?
 
case895 said:
You are both connected to earth. The fact that the two are that close is irrelevant.
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Hmmm...various fencing sites seem to think you should be 10m between earthing for various utilities/fence, etc., on account of electromagnetic fields possibly forming that might interfere with the other earth. Can just about understand that, but not what the consequences would be above ground! Long time since physics in high school...
 
The electricity pole you refer to ,is it a wooden pole which merely supports the cable? If so ,you can put the earth rod as close as you like . If it has a pole transformer (metal box ) at the top ,then try to keep your earth 10 metres away.This is because a pole transformer is earthed on the low voltage (mains 240 volt ) on the neutral line. It is potentialy dangerous to be too close it could cause interference to sensitive equipment ,tv radio etc.In the event of an earth fault at the consumer ,there is a possibility that the fence could wind up carrying mains current. This is rare but I have seen it happen.
The most common way domestic supply is earthed is by Protective multiple earthing . At your cutout box and metre there will be an uninsulated connector block with yellow wires with a green tracer running to it . One of these wires will run to an Earth Rod which will have a metal label warning you not to remove it.
There is another very rare system where the earth and neutral are linked in the cutout box.

To test your fence .Put a metal peg or post into the ground a couple of meters away from the earth and in the direction of the fence line . Earth the fence wire by laying 5 or so metal fence stakes against it earthing it effectively . Using a tester carefuly measure between the earth pin and the second pin you put in . There should be only a low reading . I can guarantee however that it wont be low. This is because I have yet to see anyone earth their fence properly in this country.

How to earth your fence. Go to your local electrical wholesaler ,insist that you are trade (and expect a discount) and want 3 copper earth rods and connectors .Bang the three rods into the ground a metre apart and link them with insulated copper earth cable attach the earth from your fence unit securely to the three rods. This will give a good earth in most soils .
 
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By the way, you can have the earth cable from your fencer unit to your earthing location ,as long as you want. You are not limited by the bit of cable sold with the unit . It could be 100 metres and still work effectively providing it is heavy enough .
 
Thanks, Mike007! I do think there's a transformer box at the top. I think I'll call the leccy people this morning to ask about it, and move the ground stake a few metres farther along just to be safe. It's about 10m right now.
 
Fully agree with Mike. I worked with electric fencers for years and his advice is spot on. As far as I was always aware, the fencer units earth stake should be 10 metres away from any other earth. One of the reasons being, that most modern electrical systems are protected by RCD'd (Residual Current Devices) These detect voltage at Earth and then trip out for safety. If your fence line shorts to earth, either via vegetation or through a horse, if your fencer earth is too close to your household earth, the RCD will detect the fence voltage and trip your trip switch. Most household earth systems are connected to the water main, but with the advent of much more plastic piping they may also have an earth spike driven into the ground near the house. So I would ensure ten metres away from this.
 
OK, haven't heard back from the leccy guy yet, but have measured: at the moment, it's 10m away. In the morning, I'll have a look and see if I can move it another 2m or so. Do I need to be worried about the outflow pipes from my house? Have a septic tank/well instead of mains, but no idea where the pipework is. The line from the well and the septic tank itself are on the other side of the house, though.
 
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