Electric Fence Questions

[erinem]

I just bought an electric fence charger, and I want to set up a temporary electric fence for grazing goats and keeping predators away from some chicken tractors. The instructions that came with the charger say I need 3 ground poles, 10 feet apart and at least 50ft from any underground metal pipes. The area I wanted to fence in first is my overgrown back yard, which is surrounded by a chain link fence on 3 sides (but contains landscaping and garden that need to be excluded from the goat area) . Will the metal posts supporting the chain link fence be enough to mess with the grounding of the fence? Also, I know there are old metal pipes running from my well into the side of the house, but the house has been replumbed since then with PVC, so they're not connected to anything, we've just never taken the time to dig them out. Do we need to avoid those too? What are the odds that the pipes running from the house to the septic tank in the middle of the back yard are also metal?

The ground here is pretty dry and sandy, so I guess I may need to run a ground wire with the hot wires... has anyone had experience with this type of grounding?

Any advice is appreciated, thanks!

 

[deedly]

I have ran many electric fences and have never paid any attention to underground metal pipes. The one I have around my chicken yard is grounded to the meter base ground along with the plumbing for the house. There are metal pipes there and no problems. Just have to make sure that your hot wires are not grounded and you will be fine. You should run strands of ground and strands of hot wire. It takes 4 strands to keep goats in. I like to stagger my strands, ground-hot-ground-hot. One other thing, make SURE not to drive your ground rod down into any buried electric line, or plumbing. That might be the reason they are warning against underground pipes.

 

[patandchickens]

The instructions that came with the charger say I need 3 ground poles, 10 feet apart and at least 50ft from any underground metal pipes. The area I wanted to fence in first is my overgrown back yard, which is surrounded by a chain link fence on 3 sides (but contains landscaping and garden that need to be excluded from the goat area) . Will the metal posts supporting the chain link fence be enough to mess with the grounding of the fence?

No no no, you're fine, that is TOTALLY not the kind of "underground metal pipes" they are talking about

-- they mean buried metal water lines or the like

Also, I know there are old metal pipes running from my well into the side of the house, but the house has been replumbed since then with PVC, so they're not connected to anything, we've just never taken the time to dig them out. Do we need to avoid those too?

If you are SURE the metal pipes are totally orphaned and not connected to any house metal or well-shaft metal anymore, then it is ok. The reason you care about buried metal pipes is that stray voltage can electrify them -- for instance if you have buried metal pipes serving a sink or metal auto-waterer-served cattle trough, if there is a circuit fault in the fence you can get a nontrivial zap from the faucet handle or animals drinking from the trough. IN PRINCIPLE you should of course never let faults happen and should be out there 24 hrs a day with a fence tester to notice when something goes wrong I guess LOL but realistically of course these sorts of problems DO occur so it probably IS smart to keep your ground rods away from buried metal pipes.

The reason you want to keep the ground rods away from utility-pole ground rods is that a lightning strike to the utility lines that gets drained off thru the ground can excessively electrify your fenceline for a moment, which is bad for anything touching it at that moment.

The ground rods do not need to be right by the charger, you know. You can run a reasonable-length leadout wire from the charger to wherever it's most convenient to put the ground rods. Most people select, not only somewhere away from buried metal pipes or utility grounds, but also somewhere that tends to stay reasonably damp (thus conductive). A low spot, or somewhere that gets roof runoff.

What are the odds that the pipes running from the house to the septic tank in the middle of the back yard are also metal?

I would say very low, unless it is quite an old house and has cast-iron sewage pipes.

The ground here is pretty dry and sandy, so I guess I may need to run a ground wire with the hot wires... has anyone had experience with this type of grounding?

You mean a positive-neutral fence, where the ground terminal of the fence is wired to a neutral wire run on the fence, so that an animal will get zapped if it touches both a hotwire AND the neutral wire at the same time, no matter what the conductivity of the soil is?

They are a good thing to do if you are on soil with major serious dryness (or frozenness, or solid rock) issues. However under conditions where a traditional (grounded) electric fence WILL work, it is superior to the pos-neutral configuration. I would suggest wiring yours both ways -- even if you're using neutral wires on the fence, ALSO sink several ground rods in a damp spot -- so that you get the best of both worlds. That does not harm fence performance at all.

The main thing is to have the neutral wires as close as possible to the hotwires (so that animals are *likely* to touch both simultaneously) *without* having them so close that you get inductive loss. (A non-charged wire running close alongside a charged wire for a long distance will acquire an induced charge which saps some of the strength from the hotwire). 6" is good for not-super-long fences; for very long fences you may need more separation.

Good luck, have fun,

Pat​