Electric Fence Basics

[cmom]

I could only get mine in about 3-4 feet before hitting bedrock. And I did buy copper this time around :/

On a tread by @Howard E is a link that explains grounding very well.
http://www.cyclopselectricfence.com/most-common-electric-fence-grounding-issues/

https://www.backyardchickens.com/threads/electric-fence-setup-with-grounding-instructions.1347817/

 

[cmom]

I could only get mine in about 3-4 feet before hitting bedrock. And I did buy copper this time around :/

Multiple ground rods may be needed.

 

[humblehillsfarm]

On a tread by @Howard E is a link that explains grounding very well.
http://www.cyclopselectricfence.com/most-common-electric-fence-grounding-issues/

https://www.backyardchickens.com/threads/electric-fence-setup-with-grounding-instructions.1347817/

Wowza my setup is so hodgepodge I now realize.....

 

[U_Stormcrow]

OK, ground rods.

If you are building a house (I am), you use copper ground rods, because the house is full of copper wire. Mixing metals will lead to accelerated corrosion - which is why you should never see a mix of Aluminum and Copper wires in an electric box anymore, and why they use (per code) special anti-corrosion "goop" when connecting the service entrance wires (stranded aluminum) to your meter box, from which all your household copper will be run. Otherwise, you would have wires corroding inside their insulating jackets. Its called "galvanic corrosion" and its bad. If you have copper pipe connected in your house to old steel or the like, you can see it in action. If you could see inside your hot water tank, it has annodes which are INTENDED to corrode to protect the rest of the system via the same process.

Because your electric fence likely uses galvanized steel wire, steel ground rods are called for. You can use those mighty expensive special purpose galvanized steel rods @ $28 a piece, or you can used dirt cheap 1/2" (#4) or 5/8" (#5) or even 3/4" (#6) steel rebar. Galvanization of the steel rods is simply coating them in zinc - the zinc will corrode before the steel starts to rust. No galvanized steel just means that you have to replace the rebar more frequently (maybe 8-15 years, depending on soil conditions and steel thickness - faster in really bad environments with high salt and moisture).

Modern code calls for ground rods to be placed 8-10' apart, driven into the soil at least 6-8'. The concern with a singular ground rod is that soil - particularly dry soil - isn't all that conductive and has a relatively low "reserve" into which a lot of electrical power (such as a lightning strike) can be shunted. Exceed the reserve, and the lightning tries to find another path - such as through your expensive electrical equipment. Imagine the dirt the ground rod is driven into as a large bathtub for power. Sticking two rods right next to each other is, in essence,having two faucets into the same bathtub. It doesn't keep the "water" (lightning) from overflowing. Multiple rods, spaced well apart is like multiple bathtubs, much harder for the lightning to overflow.

If you put a lightning arrestor on your fence, it needs to be at least 50' from your charge controller, and needs at least two ground rods, spaced about 10' apart. So they tend to go to the opposite corner from your charge controller.

So why do I keep talking about lightning? Because the whole idea of the electric fence is to create a really really good ground, so that when something almost touches it, the spark jumps - like lightning, or the tip of a spark plug - that air gap and gives them a nice jolt. You are making is so it wants to go to that nice attractive ground.

In point of fact, I plan to take my two "cold" wires (as I'm wiring, from the ground up: hot, cold, hot, cold, hot) and connect them to ground, so something that somehow contacts a hot wire without touching the earth will still get a shock if it also contacts one of my cold (in this case, grounded) wires. Which will also help mitigate the fact that my fence is on a sandy hill which tends towards very dry for part of the year, sand being a very bad conductor. The rest of the time, the clay below that sand actually makes a great conductor, but I want my fence at peak efficiency year round, not just in the (current) rainy months.

/edit and on that happy thought, I have more woods to blaze a trail thru, and one more log to install as a fence post before I can setthe last side of my fence. Have a great morning all.

 

[nao57]

Perhaps this will help?

https://www.backyardchickens.com/threads/electric-fence-setup-with-grounding-instructions.1347817/

Also, when buying a ground rod, the E fence people will tell you to ONLY use galvanized steel ground rods. 1/2" is enough. Copper doesn't exactly corrode, but does get that green scaly film on it that doesn't conduct all that well. And straight rebar, steel fence posts (even painted ones) eventually rust and don't conduct as well.

They talk about multiple ground rods and pounding them in 8 feet or more. My thinking is enough is enough. If fence is testing high voltage and you are getting a good shock, and if you do the ground test outlined above and don't have any voltage left in the ground (pun intended), you have a good ground system.

People like to steel copper also. Its the theft of choice for wandering drug addicts.

 

[nao57]

@nao57 I was just at Tractor Supply buying stuff for my (AC powered) electric fence. Anything over 1J of output will be rated for big predator. Anything under 1J wasn't - so that's my guide on requirements for keeping wild hogs, wild dogs, the FL brown bear, etc out of my homestead area. Based on my readings, most critters will only test an area of the fence once - the shock is perfectly painful and perfectly safe, unless they are caught in the fence somehow (antlers, most commonly) and unable to escape. It does no damage to the trees, though you should still use insulators if you are using trees as your posts (as I am in some places). Even covered in rain, the current (which is high potential [voltage], low current [amperage]) will simply propagate down the bark of the tree in the case of a short, doing no damage to the tree's heartwood.

I bought the electric charger for $100. Bought 1/4 mile spools of wire (14ga for the hot) for $25 a piece, on special. I think I spent $38 on a half mile (17 gauge) of wire to go between the hots n my 5 wire fencing. From the ground, it will be hot, ground, hot, ground, hot. The spring assemblies for gauging wire tension were about $9 each, and the in line wire strainers about $4 ea. 2" barbed staples (a lot of them) around $20, a 200 pack of short insulating tubes was around $12, and I paid about the same for 25 packs of plastic screw in insulators, a bit less for poly insulators for the corners which did not have integral screws. More money in crimps to make loops where I start and end wire sections of the fence.

Ground bars will be 5/8" rebar, and I have some heavy insulated aluminum wire already for connecting the unit to the fence (#2 Mobile Home SE wire). All told, I'm into this for about $350, and will be fencing an area about 250x400. The gates (2 @ 12', 2@ 4') will end up costing me nearly as much, when all is said and done, and I'll have fenced about 2 1/4 acres. I'm not using any Tposts or the like, just cut the timber I need, dig a deep hole, and place it. Yesterday I set two 7 1/2' poles of at least 10" dia black oak just over 3' in the ground, each. By comparison, driving the rebar grounding rods will be downright pleasant. I have clay soils.

Hope that helps. (also, my charger is WAY larger than I need for such a small area - but will allow for future expansion, as my total property is 30+ acres, and I expect multiple subdivisions of it with electric fencing sections.

Thank you very much for going into this! Its so helpful. I think we all are interested in this also, especially with society acting crazy how it is.

I'm curious also, do you guys think electric fences can work on '2 legged night predators' also, the ones that are smarter? (looters) (And curious why they weren't trying to use this stuff in Seattle, etc.)

Also, I have a fix for your installing them in clay soil! XD I'm glad I can help a little on this.

We have the same clay soil, its all super hard and won't give. And when you try to do fence posts in it, we would literally have to scalp our hands with torn up skin and blisters.

So we figured out there's a trick where you can run the garden hose over a spot for a few minutes. Then ram the stake or thin post in. And then just keep moving down the line. Its a bit of brain work, but it makes it about 10 times easier. (No joke.) Then you can turn the fence on after all the posts are in. This is how I installed my back chicken fence. (Although I don't have it electrified yet.)

The ground rebar...can it be any size of any metal? When you guys are stating the rebar ground rods, I couldn't help but wonder if there was a reason you had to be precise on those?

 

[U_Stormcrow]

Thanks Nao57. I've driven plenty of rods, copper and steel, into the ground around here. Yes, a bit of moisture helps loosen the clay. I also have one of those throw weight things used for driving T-posts, and a sledge. Someone holds the rod at the bottom, I climb a ladder, and start dropping the TPost weight. Can usually get it to drive the rod a few feet before it gets persnickety. Come down the ladder a bit, repeat., repeat. Finish with the sledge.

Thicker diameter rebar bends less, easier to drive.

and I listed its sizes both ways. In the business, they likely say #4 bar or #5 bar, that just means 1/2" or 5/8" respectively. Usually purchased in 10' or 20' lengths. Which, honestly, are a pain to transport if you don't have a long trailer. A good hacksaw blade in the parking lot is the answer. Cost you a buck or three. You may be able to buy them in 5' lengths at the big box store, but its kind of rare. The "stubs" of rebar used when pouring concrete in multiple lifts are typically only around 3' in length, and that just doesn't make a good ground - you'd spend more in wires and clamps connecting them together than you'd save buying them precut at that length.

And no, no reason to be precise - thicker bends less (easier to drive in the dirt if you are pushing it deep, but harder to get started), takes longer to corrode in the soil, and has greater capacity for current - but is also heavier and more expensive. Go with what's easiest and available to you. Once everything is in place, if your fence tester says you need more ground... that's an easy fix.

 

[nao57]

So something new just came up.

I was thinking about how to try to set something like up when I realized...

Wait a second, its getting cold. I better ask the guys what happens with electric fences when there's snow on the ground or when it rains?

Does it still work then? Can the battery or the fence kit get damaged also from the water causing weird unexpected stuff to go on? And what happens?

 

[U_Stormcrow]

Rain. NOTHING. Its like urinating on an electric fence - unless you are close enough to lick the fence, surface tension causes the stream to break into droplets. Those air gaps between the droplets are high resistance - an air gap - and the charge can't find its way to ground.

When the water is falling from 10,000 feet, its well formed into droplets. Only issue is if you have a solid stream of water running down your posts -- and that's only a problem if you didn't use insulators.

As to snow??? Not in my experience, I will leave the query to others. Rain, though? Rain I know. Welcome and well met from sunny Florida.

 

[Howard E]

Rain has no affect on an electric fence, unless you are running it close to the soil and water puddles up to the point the fence is submerged. That would bleed it down to nothing and drain your battery "toot sweet"!

Pure snow, like pure water, is a poor conductor of electricity. So does not ground out your fence. Had 4 hot wires buried in 20 inches of snow a year or so back, and kept right on working.