testing electric fence?

My mom has a vegetable garden surrounded by railroad ties. It is fenced to keep the deer out. To keep the chipmunks, woodchucks and rabbits from trying to get through the fence, my father ran electric fence wires along the tops of the ties.

It does not appear to work. The animals are running along and crossing over the wires. The charger puts out 20,000 volts a/c. My meter doesn't go up that high. Searching finds there are $125 fence testers.

When the wires are attached to the charger, the fence okay light on the front does not flash. But the unit does click every second. When the wires are removed, it clicks and the light flashes. For circuit resistance my meter showed no short.

Does anyone know about these things? My mom is using a farm product in a suburban backyard and there aren't many around to ask.

Don.

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Reply to
Don Wiss
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Electricity works in a complete circuit. Does the fence charger have a way to connect to earth ground?

On the top of the railroad ties, please try running a second wire, this second wire connects to earth ground. The second wire should be close enough that a critter can easily touch both the fence charger wire, and the ground wire.

OTOH, maybe the rail road ties may be grounding the fence charger. They do sell plastic insulators, which may be needed.

Reply to
Stormin Mormon

It worked for years. There was even a charger before this one. But my father was alive then.

There are two electric fence wires running across the top. There is a grounding rod. There are insulators. There is lots of wire.

Don.

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Reply to
Don Wiss

Check with the local humane society. You may have the new non conductive rodents. Just like glyophosphate, and roundup resistant crops, there might be charger resistant rodents.

Well, not all seriously.

Reply to
Stormin Mormon

If it's AC, you can try wrapping a (insulated!) wire around one of the fence wires and feed that to a high-impedance volt meter. Or, start by using it to "power" a neon bulb (to eliminate any risk to the VOM). You'd do this with power *off*, of course. :>

Here, you're just looking to see if it is developing *any* sort of (high) potential.

At 20KV, you're not looking for a short in the "zero ohms" sense. The fence "charger" is expecting to see a VERY high resistance (megohms) when not in contact with critter flesh. It is probably only capable of putting out a few milliamps, maximum (1mA @ 20KV = 20W!!). You can make a guess based on the rating of the *primary* side of the "charger" (e.g., what does it draw from the 120VAC mains?)

Said another way, a 1mA load would look like 20 Mohms (20,000V/0.001A). If you are seeing *any* resistance on your DVM, then the fence charger thinks the fence is "shorted".

(Hint: grab the two leads of your DVM in your fingers with the selector set on highest "ohm" range. THAT is what the fence is expecting to encounter when you -- as an oversized "critter" -- touches the fence!)

I suspect the click you hear is the charger shutting down and restarting, cyclicly.

Reply to
Don Y

if the railroad ties are treated with creosote or other noxious chemicals you are eating them. the chemicals migrate from the wood and get into the dirt you vegies are planted in.

Reply to
bob haller

Any charger I've run into clicks every time it pulses. If it's not clicking it's dead. The redneck method of testing the fence is to pick a blade of whatever you've got growing and lightly touch the fence. The dumb redneck method is to piss on the fence.

If the smaller animals are on top of the ties when they touch the wire they may not be grounded. Or they might just be hungry. Mix an elk, a field full of alfalfa and an electric fence and you'll find out how many feet of wire, insulators, and posts a determined elk can drag.

Reply to
rbowman

There's a diagram here showing how one works with farm animals. The animal completes the circuit when it touches the wire. I wonder if using something like screen door screen on top of the ties could act as the earth. Connect the screen to the ground of the fencer. Then run the hot wire slightly above that. You'll have to keep the hot wire from contacting the screen. The animal needs to make the connection between the two. Normal insulators probably wouldn't be practical. Maybe buy some pvc pipe and lay it on the ties. A single 10' piece of pipe would make quite a few wire stands. The wire will have to be tight to keep it off of the screen even with many supports. One can buy fence stretchers. Maybe some springs at the end(s) to keep tension? Testers at Amazon:

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Price range is $10 or a bit more. One can also buy polywire, polytape, and polyrope. Maybe the visual part would help after the animals get a shock or two.

Reply to
Dean Hoffman

Buy her some Rat-Zapper's from Victor Pest

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They are battery operated (AA's) and work like a champ for mice and gophers. We had them to control field mice in the garage but this year we've had a slew of chipmunks all of a sudden. Set them out near the garden and flowers where the little bastards were digging and feasting.

Dumbbells walk right into the trap even with any bait (we use a couple of pieces of dry dog food for mice) and they get zapped. One trap netted four chipmunks in one day. Not much of a problem any longer. If you put them in the garden you need to protect the trap from rain but Victor makes an enclosure for that purpose. You could also make one out of something like a large Tupperware container.

Reply to
Unquestionably Confused

Does the fence pulse have enough energy to cause a magnetic compass to "jump"? If so, hold a compass up to the wire and see if it jumps when the pulse fires. If it does, move further down the line until it stops jumping. The short to ground should be right there.

Reply to
mike

The smart ass redneck way is you get a city cousin to piss on the wire.

Reply to
Ken Olson

Very interesting. I usually visit mom once a week. Your suggestion, and others here, will be useful when I visit next week.

Don.

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Reply to
Don Wiss

We are not currently trapping. When my father was alive he trapped. One summer he got 32 chipmunks. If my mother successfully caught a woodchuck, she would not be able to lift the trap. When we tried is was hard to successfully trap just before I visited. (Mainly as no woodchuck would go in the trap. Instead squirrels would trip it.)

I'd like to fumigate the woodchuck burrow. You have to seal up all but one entrance. Problem is one entrance is now under the neighbor's tool shed.

Don.

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Reply to
Don Wiss

First, there aren't many vegetables in the garden. It has become too shady. Most vegetables are grown in a community gardne. And since deer love hostas, those plants now live in there.

I looked up creosote. I found "Creosote that seeps into the soil may damage roots directly, but plants will not absorb the substance into their root tissue." From:

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Don.

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Reply to
Don Wiss

I thought about a neon bulb tester. I'm sure if I hunted I could have found one in my father's workshop. I can take mine out next visit.

When I wrote the original post I realized I should have brought back with me the instructions sheet. Without it I don't know much about the charger. I do know it is an Agway ALI30C. But I can find little about it on the web.

I did not see any resistance in the DVM. What I'd like to have is:

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But considering that my mom is 94 and it isn't that important, it is a bit of a stretch.

I tried it and I couldn't get any reading.

Don.

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Reply to
Don Wiss

I'm thinking there is enough leakage through the logs to make the controller think it's a short circuit. Your meter only uses low voltage to measure the resistance. Maybe the old fence controller had more output and was able to overcome the resistance to ground. I'd use the yellow plastic insulators to keep the wires from touching the wood.

Reply to
Art Todesco

The current controller worked for years before this summer. The prior one worked for many years before this one.

It is a large and complicated setup done by my dad years ago. No one is going to rewire it now.

Don.

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Reply to
Don Wiss

Find a city-slicker, grab their hand with your left, and grab the fence with your right. You'll find out rather quickly if it is working properly.

Reply to
Scott Lurndal

That's what I was thinking too. Normally an animal is grounded, standing on the earth, the wire insulated. The animal completes the circuit. Here the wire is on top of a creosote timber, sounds like the small animal, eg rabbit or squirrel is on top of the timber too, so there is no circuit.

Testing with a cheap neon tester like you'd use for AC or for a car ignition tester would work.

Reply to
trader_4

Or steal one out of an illuminated wall switch.

OTOH, it *appears* (from your description) that the fence charger indicates "power available" via the light. So, you can probably use that and jigger around with the fence wire to see when you've cleared the "short" (keeping in mind that a wet branch leaning on the wire is a short!)

Assume power in = power out, for starters. So, if you can get a voltage (or current) rating on the output side, you can guesstimate the current (or voltage). I think you'll find damn near anything will look like a "short" at the voltages involved.

Compare what the fence reported to what your hands holding the test leads reports.

Same as the fence, eh? :>

For a definitive answer, you need a higher impedance VOM. But, chances are, the problem *is* a "short" -- you'll just have to decide if it is the wooden fence post to which the wires are attached... or, the insulation on one of the wires feeding the fence... or...

But, you *know* the charger behaves differently with *no* load connected! ASSUME it is working in that configuration. See what you can do to make it stay working while you have fence wire attached.

Reply to
Don Y

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