Introduction: Install an Underground Fence
This Instructable is intended to be a supplement to the manufacturers how to guide with some diy tools & tricks that I came up with to address the common installation challenges. The installation process is almost identical for all of the wired systems, so improvise, adapt and overcome as needed. The kit that fit ( most of) my needs was the Sportdog 100A with 1000 feet of 18G wire. The kit also came with 100 flags, a dog receiver collar, 2 water ( resistant) wire splices, and an excellent installation and training guide. The kit did not come with the wire installation staples. Fortunately, the website recommended them as an add on. They are heavy steel wire staples about 1.25" across the crown and 6" long. I used 200 over the 1200 foot installation run, most of which was lawn/ trench. I could have used 50 more in retrospect.
I will address supplies and tools in each step.
Step 1: Make a Plan or Plan to Fail
KNOW WHERE YOUR UTILITY SERVICE LIES! Get them marked, it's free. Ignore this step at your own peril.
Most installations will be a single loop perimeter setup. This is one wire around the desired containment area with a supply lead and possibly driveway/ sidewalk crossings. I'll stick to that as it was the nature of my project. There are lots of resources for more complex configurations, the kit manufacturer is a good place to start.
I had to cross 2 concrete driveway sections in my project. I was able to use wood expansion joints with shallow slots cut using a skill saw in both cases. I've included a photo of the mfg instructions as they are clear and concise.
Mark the desired wire path using marker paint. Marker paint is with the spray paint in most big box stores. The marker tool is not necessary, but I already had one. Pay attention to large roots as they can become challenging obstacles.
Step 2: Cut the Wire Trench
Cut the grass very short before trenching as it will leave the area cleaner to do your work.
I used a gas edger with a modified blade to make the trench. My edger has a forward rotating blade ( cutting bottom sweeps to back). The blade, as pictured, has a slight bend on the trailing edge to make the trench wider and to help pitch the dirt to the side.
The other trick is to pull the edger backwards along the marked line instead of going forward. This will keep the majority of the removed trailings from going back into the trench. The example on the open dirt shows how much wider the trench is using the modified blade.
Step 3: Twisting the Wire for Signal Free Wire Crossing
This is used for the run from the transmitter to the containment loop path. It can also be used to make gate areas. The desired twist rate for signal cancellation, is 10 twists minimum per foot.
Using a variable speed drill with a j hook in the chuck, measure a piece of wire 1.5 times the distance of the desired run length plus 3-5 feet additional tail for your loop end to connect to. Pair this up with the main wire and securely loop the end over a small cable gimbal. Hook the gimbal on the drill and have a second person slowly ( SLOWLY!) operate the drill while you pinch the pair of wires to achieve the twist. Work your way down the pair, controlling the twist as you go. The twist rate will probably be greater than 10 twists per foot, but that is fine. If you twist too long of a section, just cut the excess off. Also, remember to leave the tail you added in for the loop termination connection.
Step 4: Install the Wire Into the Trench
You'll hear that this is the most difficult and time consuming step. That's probably correct. I've attached pics of a device that works like a fishing rod/ reel only backwards. The wheel at the end is a 3" garage door cable shiev I purchased at a Home Depot . It would have been better with a 4", but that box was empty. Use what you can find...larger diameter is better to keep the shiev bearings out of the dirt. I did have to stop and spray them out with water a couple times... No big woo though. There is a tiny eyebolt in the strap over the shiev that serves as a wire guide. It would not keep the wire aligned without it. This tool was used as a push along, you might consider making yours as a pull type unit so grass and dirt won't be forced into the wheel head. In retrospect, that seems to make more sense.
At the conclusion of the loop, I connected the loop end to the tail remaining from the wire twist step by soldering the well twisted connection then coating the bare soldered with liquid plastic. Once the liquid plastic hardened, I then pushed that connection into a supplied water resistant connector case and sealed that shut with silicone RTV.
Secure the wire with staples as needed, but don't drive them all the way down until you have a successful loop test. It would be a pain removing that many that were driven home.
If you live in an area that has significant ground temperature change, you might consider adding a small Z bend in the wire every 50' to allow for contraction during cold months.
Good luck with your project.
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