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Thursday, 10 March 2011 19:21

Joining Wire - Crimps, Knots & Inline Strainers:

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At some point on your lifestyle block you'll need to join 2 wires together on a fence line. It might be to repair a broken fence, you may have to cut a fence temporarily, or it could be where a coil of wire runs out and you need to join onto another, or at the end of the fence where you're tying off to a strainer post.

The easiest options for the novice are to either use a permanent wire strainer at one end of the fence line, or to use something like a Wirelok (or Fastlok) or Gripple to put a join anywhere along the fence line. Permanent wire strainers can also be used in the middle of a fence line to join 2 wires.

Crimp sleeves and wire knots are another alternative, crimps are by far the strongest method of joining wires and are certainly easier to master than tying wire knots.

So how strong are each of the joining methods? Breaking strain is measured in kgf - kilograms of force. The minimum breaking strain of standard 2.5mm fence wire is 620 kgf.

Type of join 
Average breaking strain
Double Loop Knot
290 kgf
Reef Knot
440 kgf
Figure 8 Knot 470 kgf
Crimp Sleeve 620 kgf


Double loop knots were the preferred method for joining 2 wires in the 'good old days', but nowadays their used is discouraged. As you can see from the figures above, a crimp sleeve (when properly applied) is as strong as (or stronger than) the original wire itself.

A permanent wire strainer is designed for 150 Kgf tension which is the recommended tension for a wire and batten fence. Permanent electric fences are strained up to a little over half that tension.

Permanent Wire Strainers (PWS)

permanent wire strainerThese are a really easy way to tie off a wire, with little experience or skill. The tools needed are pretty basic - you can get away with 1 or 2 sets of chain strainers (instead of needing at least 7 or 8 sets like contractors do) and you'll need a ratchet handle to crank them up. Some PWS like the Gallagher one pictured have a square drive on one side that you can tighten (carefully) with a spanner. PWS are available in insulated versions for hot wires as well as standard versions for plain wires. Gallagher also make a "termination kit" - ready to go with a stainless steel wire loop that eliminates the need to tie off to a strainer post with wire. The big advantage with PWS is that you're able to re-tension wire, can drop a fence and put it back up again, and if you've got enough spare wire wrapped onto the spool - repair a snapped wire by pulling it out to give you enough wire to put a join in the line.

 

fastlok wirelokWirelok & Fastlok Joiners

Similar to the gripple but designed to work without a proprietary tensioning tool. You feed a wire in from each side - in through the small hole, out through the large hole. Inside the zinc block are stainless steel springs that stop the wire from drawing back out again. You use chain wire strainers to tension up the line, or can use a hand pop riveter to tighten by pulling up one of the protruding wire ends. The only drawback is that you can't back the wire off once it has been inserted in the Wirelok.

grippleGripples

Gripples allow you to join and tension wire. Insert both wires through the Gripple - one from each side. Tension the wire with the Gripple Tensioning Tool. You can back the wire out of the Gripple with a special setting key. You can also tie off at a strainer post by sliding a Gripple onto the end of a wire, looping the wire around the post, then inserting the wire tail back through the Gripple. Gripples come in different sizes to suit different thicknesses of wire.

Crimp Sleeves

crimp-sleeveAs previously mentioned, crimps are the strongest join you can put in a wire. They're also an easy way to tie off a wire strain in a new fence - with the wire tied off to each end strainer, using chain wire strainers - strain up at the 2 ends, slide a crimp over the ends and crimp off with the wire under tension before removing the chain strainers. It's important that you start at one end of the crimp sleeve and overlap all your crimps.

The only real downside to using crimps is the need to buy a crimping tool such as a set of Eze Pull or Eze Crimp Fencing Tools. Your Eze Pull tool should come with a set of instructions on how to use them. The Eze Pull 5 in 1 is the best option if you want to be able to crimp all wire sizes (2.5 /3.15 /4.0mm) as well as pull staples. Be prepared to part with over $200 to buy a pair, but if you've got the work for them - it's money well spent - if you ever use a set to strip old battens off a fence line you'll appreciate why.

Ezepull

The Eze Pull Fencing Tool - for pulling staples, cutting wire and joining wire.

Tying a Figure 8 Knot

tying a figure 8 knot in wireThe 2 wires to be joined are looped over each other as shown in the illustration to the right. Leave 250-300mm of wire beyond each loop. After the wires are strained up and the knot pulled tight, the surplus wire ends are wrapped around the line wire and snapped off neatly rather than cut as shown in the photo below. The result is a smooth finish and you should be able to run your hand along the wire and over the knot without scratching the skin. It looks hard to do, but is remarkably easy after some practice.

figure 8 wire knot

 

 

 

 

 

 

 

Do not

Do not leave the ends sticking out of a knot, it doesn't look good and it's a hazard to animals and humans - it's one of my pet hates.

 

fig8_wire_knot_2