Build An Electric Bear Fence

[ndbwhunter]

You can buy heat shrink at Lowes ot probably any automotive parts house.

I've seen the stuff there, but it's usually not advertised as non-conductive. I did find some stuff online at US Plastics. It is "highly non-conductive", but the smallest size is 5/8" and clear in color. I'm not sure if it would shrink down enough to fit on a carbon arrow.

 

[rayporter]

try this and report back. scrape off the coating on an aluminum shaft and apply heat shrink. hold the shaft by the heat shrink and touch the fencer with the shaft while you hold the ground wire in the other hand.

i did read that you are using carbon. but humor me, you might get a laugh at my expense.

 

[ndbwhunter]

try this and report back. scrape off the coating on an aluminum shaft and apply heat shrink. hold the shaft by the heat shrink and touch the fencer with the shaft while you hold the ground wire in the other hand.

i did read that you are using carbon. but humor me, you might get a laugh at my expense.

This sounds like a good idea....

 

[Colberjs]

I've seen the stuff there, but it's usually not advertised as non-conductive. I did find some stuff online at US Plastics. It is "highly non-conductive", but the smallest size is 5/8" and clear in color. I'm not sure if it would shrink down enough to fit on a carbon arrow.

Heat shrinks main purpose is to re-insulate bare wires that have had to been soldered or spliced in some fashion. I've always seen it sold in the electrical department at Lowe's. No other reason they would sell it there that I know of.

 

[Where's Bruce?]

http://abcnews.go.com/WNT/video/camping-expediting-awry-polar-bear-attacks-tent-19798559

 

[Kevin Dill]

I went to my local electrical supply store (that's all they sell...electrical stuff) and asked them about heat shrink tubing. There was no hesitation in their answer: "All heat shrink tubing is non-conductive except for some very specialized types designed to conduct voltage". The whole purpose and creation of heat shrink tubing was for use in electrical applications as an insulating cover/shield. So...presto...I handed the guy a carbon shaft section and he promptly selected the correct size tubing. He explained that hst will shrink to 50% of original diameter. I asked him for 4' of it (comes on a bulk roll) and it cost me $3.00...yep three dollars. AND...it is non-conductive. I checked it for continuity and any trace of voltage when hooked up to a 12v charger...nada.

 

[ndbwhunter]

Thanks for the information, Kevin. I found a source for the new bi-polar fence tape, and think I might give it a shot. Seems like it would save a little weight without having to use a ground rod....not that the rod weighs a lot anyways though. What are your thoughts on using this? I don't have enough experience with electrical stuff to know any better.

http://www.horseguardfence.com/newprod/news.php

 

[ndbwhunter]

I found a link to a study that was conducted in MT on the effectiveness of electric fences on grizzly bears. The study found that energizers with an output of less than 0.11J were not effective in keeping bears out of the fence. They recommended an energizer with an output of 0.2J or higher. The speedrite AN20 has a maximum output of 0.04J. Do you guys feel like 0.04J is enough, or does it depend on the voltage?

 

[F16pointy]

Joules are not a good way to assess something like this in my opinion. These fences should act like a tazer in a way. Where the energy is stored and just waiting for a ground. Joule calculations are very convoluted and don't really tell you much. Look at what the output current and voltage are, those are what will overcome the resistance of the animals skin and fur. So look for a decent current and high voltage, there is a lot to calculate in regards to electricity and what will work. If your load is calculated right and you have a good ground the 5800 volts (open circuit) that the AN20 puts out will be more than enough to deter a bear. According to their data sheet at 2000 ohms it will still put out 2800 volts. If your ground is bad you increase resistance which then decreases your voltage output. Bottom line is joules are ok to use as a gauge but I would look at the voltage your putting out and possibly the resistance of your components. Then ensure you have a very good ground rod and ground when using it. I plan to build one for family fishing trips and will use the AN20.

 

[Kevin Dill]

Okay...project has been completed a while, but just now posting the goods.

I made 6 x 3-pc posts out of carbon arrows. Connections are Easton inserts and a piece of 8-32 all-thread. I glued a loop of GloWire cord into the top to serve a guy attachment if needed. The posts work fine but are flexible and benefit from having a guy-out.

View attachment 27517

I used heat-shrink tubing for contact insulation and it works perfectly fine. No voltage gets past the heat-shrink.

View attachment 27518

Small bundle of 6 guy lines ready to attach.

View attachment 27519

White equine electrical 'tape' x 2 rolls to do upper and lower runs.

View attachment 27520

7" aluminum spike serves as ground stake.

View attachment 27521

After all the assembly/crafting work was completed I put the fence up and tested it. Essentially perfect and no unexpected problems. I used a couple of slip connectors to complete the connection on each run, as these allow easy adjustment and tensioning with very little weight. One thing I always do is to suspend the weight of the AN20 charger from a post using a drop line. The charger clips on the fence, but the weight is mostly handled by the drop line and post.

 

[Kevin Dill]

The entire kit laid out after the test run. Simple and easy to work with.

View attachment 27522

Everything except the posts is contained in one medium mesh pull-out.

View attachment 27523

Ready to pack up!

View attachment 27524

The final packed weight with all the parts plus the bag and using 6 posts is 2 lb - 13 oz. Of course I can drop weight by leaving 2 posts (6 sections) behind, plus I could presumably go with one run of tape instead of two. If I went with 4 posts and used poly-wire instead of tape, I believe I could get the weight down to 2 pounds or possibly under.

I'll be in the alpine in just under 3 weeks on a combo diy hunt, and this rig will be doing duty there. Thanks.

 

[dreamingbig]

Awesome set up!

 

[live2huntelk]

Decided to make my own portable electric fence. I contacted the Grizzly and Wolf Discovery Center in West Yellow Stone, Montana to see what they have tested and recommend. They do testing and certify different products as "bear-resistant"...saw this when we visited a couple years ago. The supervisor I talked to recommended Gallagher and gave me the western states region manger phone number for specifics. I contacted the rep and recommended the B11 energizer, Turbo wire, and live fence indicator. Based on this thread, I decided to get some carbon shaft arrows and use some binder clips (thread wire through the loops on the clips). Long story short, the carbon arrow shafts do conduct and shorted out the energizer. I tested electrical tape on the shaft and it was enough insulation to keep the energizer from shorting. This was tested using the live fence indicator as well as setting up fiberglass fence posts and leaning the carbon shaft against the wire while touching the ground....you could hear the cracking when the carbon shaft was not insulated with electrical tape....also got a good jolt when I tried take the shaft off the live fence. Did the same test with the carbon shaft against the wire however with electrical tape on the shaft.....no cracking and no shock. The live fence indicator flashes if the voltage is above 3000 volts and helps make sure the system is working properly and doesn't have a ground issue or some else pulling the voltage down.

 

[bushman]

Resurrecting this old thread, If the OP is still around how'd this work out for you. I am hoping to do one pretty much just like it for a packrafting trip to Alaska. Hoping to get it in the 2 lb range

 

[Beendare]

FWIW,
I made one of these fences back when this thread was first rolled out. I used the higher output charger, the white tape, and Carbon arrow shafts that fit inside each other [from my buddy in the industry] I use sections of bike tire inner tube to hold the tape to the stake- easy, cheap, light. I've also used it as a horse corral with the heavy fiberglass poles from Tractor supply

One thing to note, when I tested it; A good ground is pretty crucial. I couldn't get the fence to put out proper voltage with the little Aluminum stake. Voltage was low even in optimal conditions. I couldn't get it to work at all in sandy soil. My cattle buddies told me as much; a good ground is critical for these to work properly.

I ended up using 2 sections of 18" long 1/2" Cu pipe connected with a 14ga wire about 6' long, pipes 5' apart....that always works and the tape tests at max voltage.
________

An essential piece of kit is the small fence testers....gotta have one of those. With my small ground stake the fence was working...but at about 10%

 

[Kevin Dill]

I'm the original poster. I've taken my homemade fence on multiple trips and it works fine. I've made some tweaks to the poles and insulators for better dependability and ease of use.

 

[bushman]

Excellent thank you. I bought some insulators that will fit over the arrow shafts and tighten down. Can a guy get away with just 4 poles? How does your ground system work?

 

[bushman]

What tweaks to the poles did you do?

 

[7mmremmag]

So... ummm... where's the video of testing these fences?

 

[Beendare]

Heres a pic of mine on Kodiak



Worth noting to the guys that haven't used these is that any grass, brush or foliage touching the tape grounds it out