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INSTALLING A PERMANENT POWER FENCE™ |
4.1 Planning the fence layout
HANDY HINT Cut Out Switches (G6076/G6087): These isolate different sections of the fence when looking for faults. Place them at gateways or junctions where either single or multiple fence lines can be turned off. If you farm sheep intensively, you may want as many as 100 paddocks. This means the sheep can be moved daily onto a fresh paddock using a three month rotation during slow or zero growth periods. When there are lambs and ewes during spring, two or more flocks can be grazed on a faster rotation. On dairy farms 30–50 paddocks are
usually enough. Cattle are easy to strip
graze with only one wire when longer HANDY HINT Rough, stony or steep areas: With electric fencing it is easier and less expensive to “zig zag” around rather than go straight over rough, stony or steep areas. These rough areas require more posts and tie-downs, and possibly more maintenance in the future. If possible level the area first and re grass the area because animals standing on grass get a greater shock than when standing on bare soil. Re grassing also prevents erosion and weed growth. Stock will respect all fences if most of your farm fences are electrified. This means internal subdividing fences can then have fewer wires so you can build more fencing at a lower cost per metre (yard). Power fencing also makes fencing dams, rivers, trees and erosion prone areas easier. Wire and post spacing's
4.2 Selecting the correct energizer The energizer is the heart of the
fencing system so select carefully.
Gallagher energizers guarantee a high energy
pulse that will effectively
control animals even over long
distances. They are identified by their
stored energy (measured in joules) e.g.
M1000 has approx. 10 stored joules,
MBX2500 has approx. 25 stored joules.
When choosing an energizer, compare
the stored energy figure. Stored energy
is the most accurate measure of an
energizer’s capability because it is ENERGIZER FACTS Stored energy versus output energy?
For a permanent power fence system choose from a mains powered energizer, a mains/battery powered energizer or a permanent solar powered energizer. Energizer selection is determined either by acreage to be fenced or the length of fence. Both are estimates because the distance of fence can vary between two farms of the same area because of the number of paddocks, terrain or conditions. For dry country conditions, energizers have proven to work effectively over greater distances.
* A combination of Energizers may be required. HANDY HINT Energizers that display information should be installed where the information is easy to read. Battery energizers, including solar, are best placed in the centre of the fence line and protected from animals. Keep them off the ground to protect the electronic components from insects and moisture.
‡ VDE is fence distance according to the German Standards Association.This
system is not recommended. Solar Powered Energizers Solar panels convert light directly into electricity. The battery stores this electricity and operates the battery powered Energizer. This allows the Energizer to operate at night or during periods of low sunlight. The brightness, the number of hours of light and the size of the solar panel all determine how much electricity is produced.
SmartPower™ The SmartPower range introduces new generation technology that makes power fencing much simpler, more efficient and more reliable for you. Gallagher SmartPower is easy to work and live with. SmartPower MX5000 (G313)
SmartPower MBX2500 (G302) - MBX1500 (G300)
SmartPower MBX Alarm Kit (G5695)
4.3 Installing the Energizer 4.3.1 Install the earthing (grounding) system Why does the energizer need an earth
system?
It is important to follow the layout
recommended above to get the
maximum benefit. The number of
earth pegs will vary depending on the
power of the energizer and the soil
type: high powered energizers need
more pegs than low powered Location of the earth system The most effective place for the earth system is in continuously damp, high mineral soil.
If the earth system has to be some
distance from a high powered
energizer the connecting wire must be
highly conductive e.g. 250 m (820 ft)
away use 1 x aluminium coated wire
(G9290), 500 m 1640 ft) away use 2 x
G9290 wires in parallel. WARNING: Earth (ground) wire return system Dry soils have poor conductivity. For year-round dry, frozen or snow conditions an earth wire return system should be used in conjunction with the earth system.
Super Earth Kit In dry, low mineral soils with poor
earthing, eg. sandy, pumice or volcanic
ash soils, use the Super Earth Kit
(G8800).
Main causes of a poor earth are:
Test the earth (ground) system This needs to be done once a short section of fence has been built.It should be tested at least once a year or at the height of any dry period to ensure the earthing capacity is sufficient for the joule rating of the energizer. Short the fence out at least 100m (330ft) away from the earth system by using several steel stakes between the live wires and the ground. Reduce the fence voltage at this point to 2000V (2kV) or less. Using a Digital Volt Meter (G5030 or G5035) measure the voltage between the wire connecting through the earth pegs to the energizer earth terminal and an independent earth peg. This peg should be a galvanised metal rod, minimum 200mm (8”) long, and placed one metre (3ft) away from the earth rods or as far away as your DVM cable will reach (see Fig 4.11). Note: If you are using a SmartPower
energizer the earth monitor/alarm will
indicate when the earth system
requires attention (see Fig 4.8).
There should be no reading on the
DVM, however up to 200V (0.2kV) is
acceptable. If the voltage is higher
than this, switch off the energizer,
drive in more earth pegs at the
recommended spacing's and connect
Testing an earth (ground) return wire Install a standard length earth peg as close as possible to the end of the fence. Using a DVM measure: 1 The voltage between a live wire and earth wire.
2 The voltage between a live wire and the independent earth peg.
If the second voltage reading exceeds
the first by more than 200V (0.2kV)
check the earth return wire for loose 4.3.2 Install Lightning Diverters Lightning will damage your energizer
if it strikes your electric fence.
Gallagher energizers have internal
lightning diverters that give partial
protection against small strikes.
Installing an Adjustable Lightning
Diverter (G6480) will give added
4.4 Fence Construction 4.4.1 Install the leadout The leadout cable is the power link between the Energizer and the fence. The leadout cable can be either run overhead or underground. Insulated leadout cable should be used to prevent the leadout from shorting out on obstructions or the ground. ELECTRICAL RESISTANCE CHART (Fig 4.14) Use this Electrical Resistance Chart to decide which wire/cable to use.
Other examples: HANDY HINT Maintain good conductivity throughout the fencing system by always using the correct wire or cable. High powered energizers require large capacity wire or cable. Small diameter cable will restrict current flow with subsequent voltage loss on the fence. NEVER use household electrical cable. It is made for low voltage use only. NEVER use copper wire/cable because electrolysis (electrical corrosion) occurs where it joins galvanised wire. Electrifying remote areas Where the electric fence system is several kilometres (miles) from the mains power supply there are several ways to feed the power out to the fence. A Use a mains powered energizer and transmit the power from the energizer to the fence through leadout wire(s). B Use a battery powered energizer with solar panel charging - the battery is kept charged by the solar panel. C Use a battery powered energizer - recharge the battery as necessary or alternate 2 batteries. If choosing A, the options in order of priority are: 1 A well constructed 4 or 5 wire electric fence with 2.5mm (12.5g) wires connected in parallel at both ends. It can also be used to form a laneway (7 ohms/km, 11 ohms/mile) 2 1 x Aluminium Power Fence wire (G9312) (9.5 ohms/km, 15 ohms/mile) 3 1 x Aluminium coated steel wire (G9290) (11.5 ohms/km, 18 ohms/ mile) 4 1 x 4mm (8g) wire (14 ohms/km, 23 ohms/mile) 5 2 x 2.5mm (12.5g) wires (17.5 ohms/ km, 28 ohms/mile) 6 1 x 2.5mm (12.5 gauge) wire (35 ohms/km, 56 ohms/mile) If using a multi-wire fence, divide the
resistance value of each wire by the
number of wires e.g. for a 4-wire
2.5mm (12.5 gauge) fence: 35/4 =
approx. 9. Multiples of the above wires
may be needed depending on the
distance from the energizer to the
fence and the amount of fence to be
powered. The wires can be supported
on a non-electric fence using offset
brackets or post insulators. Another
option is to insulate and electrify one
or more wires in a non-electric fence, 4.4.2 Building the fence Install end strain and corner posts Decide the line of the fence then set the end strainer posts in position. A 2.1m (7ft) post, 150mm (6”) in diameter is usually strong enough. (If you are planning to hang a heavy gate from the post, ensure the post is strong enough.) Use a bedlog, angle stay or H brace stay assembly, whichever suits your ground conditions and fence type. Bedlog CAUTION: Bedlogs should not be used in soft or swampy ground.
Angle stay
H brace assembly
Install the strain insulators A Start with a 900mm (3ft) length of wire.
B Form a knot as shown and slide it firmly to the middle of the post.
C Finish with a tight tie-off. Wrap the wire 3 times around the strain wire. Cut or break off the remaining wire.
D Wind the wire once around the insulator. Bend the wire as shown (see Fig 4.19) so the strain is from the centre of the insulator.
E Wrap the wire six times from this bend.
F Tie off tightly and cut or break off the remaining tail.
INSULATOR FACTS Choosing insulators:
HANDY HINT It is important that the pull (or strain) is from the centre of the strain insulator. Install angle posts
On sharper corners you may have to fasten the live wire on the inside of the post to stop it touching the post.
Position the line posts and wires Use a wire dispenser to run out the top and bottom wires as guides for positioning line posts and tie-downs. Use 2.5mm (12.5g) high tensile wire for electric fencing because it retains its tension far longer than soft wire. It is reasonably easy to use and conducts enough current for most situations when connected in parallel. HANDY HINT Tie-downs are anchors to hold the wire
down in hollows. For Insultimber, use
the Screw in Tie Down (G6150) and the
Attach the top and bottom wires to
end strain insulators and any angle or
corner insulators. Leave the tails long
enough so they can be used for
electrical connections later.
Use a Permanent Wire Tightener G6430
(with the Wire Tightener Handle
(G6440) or Rapid Wire Tightening Tool
(G6450) (see Fig 4.24)) to tension the
wires just enough to provide a guide to
the wire height and provide a straight
line for positioning the line posts.
Use Insultimber or softwood posts on Install the remaining line posts where necessary. On flat or level ground use one post up to every 20-30m (100 ft) and three Insultimber or fibreglass droppers in between. On hilly or uneven ground posts and droppers will need to be closer together to maintain the wire height. Run out the remaining wires, tie them off to the strain insulators and attach them to all the posts and tie-downs. HANDY HINT For untrained sheep, goats and similar animals the bottom wire should be approx. 150mm (6”) above the ground to prevent them getting under the fence. The Insultimber Clip (G7040) and the Fibreglass Quick Clip (G8350) allow free movement of the wire when straining. Choosing posts and droppers There are a number of options for
posts and droppers: wood posts,
Gallagher Insultimber™, fibreglass or
steel posts. Approx. fencing requirements per km (5/8 mile):
Fibreglass posts are quick and easy to
use for permanent and portable fences.
Posts are simply driven into the ground Approx. fencing requirements per km (5/8 mile):
These amounts may vary depending on ground contour.
Tension the wires Place the Permanent Wire Tightener's (G6430) in the centre of the fence so the wire pulls in from both ends.
HANDY HINT Wire storage and handling Store coils of wire in a dry area and away from fertiliser's, lime, acids and other chemicals. Avoid dropping wire onto stony or abrasive surfaces that can damage the galvanising. Take care not to bend any wires in the coil as this makes it difficult to unwind. Join wire using a figure eight or reef knot. These will give better electrical contact than a double loop join.
All other permanent connections should be clamped using Joint Clamps (G603) to ensure tight wire connections.
Electrical connections HANDY HINT Attaching a Flexible Connector (G6050)
to the lower wires means you can easily
disconnect them at times when there is
Gates and gateways HANDY HINT For extra protection lay cable in plastic pipe. Lay the pipe with the ends bent down to keep out water.
Electrified gates WARNING: Do not rely on electric gates to get power across gateways because when the gates are open power is lost to the fence.
Install cut out switches
4.4.3 Fence protection Old non-electric fences can be made to last for many more years by attaching offset brackets with an electrified wire on one or both sides of the fence. Attach single offset wires at two thirds the height of the animal to be controlled. If sheep and cattle are in the same area it is better to use two offset wires (one for sheep, one for cows). However a single wire three quarters the height of the sheep will still protect the fence from both animal types. If the old fence is tangled or has broken wires, it will need to be tidied up. Otherwise you will run the risk of loose wires causing accidental shorting on the offset wire. Remove the worst wires and tighten the others where possible. HANDY HINT On level ground, offset brackets should be spaced approximately 20m (66ft) apart. Over uneven ground, space the offsets closer to maintain a constant wire height above the ground. Attach them next to posts for extra stability. Choosing offset brackets Wire offsets
Wooden post offsets
Pigtail offsets
Fibreglass offsets
Chain link offsets
4.4.4 Stock control during power failures Where long power failures are likely
keep a battery powered energizer as
an emergency unit or use a
combination battery/mains unit.
Animals which have grown up with
electric fencing avoid the fence but
may eventually touch the wires 4.4.5 Electrified flood gates Install an electrified flood gate to prevent animals walking under an electric fence that crosses a water course. An electric fence that is partly or entirely submerged in water caused by occasional flooding may lose most of its power. To overcome this problem install the Flood Gate Controller (G6040) between the fence and floodgate, via a Cut Out Switch as shown, 150mm (6”) above average water level. This reduces power loss through the flood gate.
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©Steve Cselka 2006 - 2011 |
symbol indicates a live, pulse-carrying wire
symbol indicates an earth (ground) wire
