Introduction to Electric Fences

An electrified fence is a fence of which all or some of the wire strands are isolated from ground. These strands are then connected to a Tru-Tek Electric Fence Energizer, which supplies high voltage to them. The idea is to have an open circuit between the high voltage strands (hot wires) and earth, when this open circuit is closed by an animal or a person (the target) standing on the ground and touching the hot wires, electricity generated by the energizer flows from the hot wires through the target and into ground, giving the target a severe electrical shock.

Fence energizers are manufactured to generate a short high voltage pulse, which travels down the fence conductors at an interval of one second.

Tru-Tek Energizers are designed to deliver a severe shock of such short duration and limited energy that it is considered non-lethal.

An electrified fence need not be constructed as strong as a conventional fence as it poses a fear barrier more than a physical barrier.

The pulse causes muscles to contract tightly and release immediately once the pulse has passed, usually throwing the target away from the fence.

An electrical fence can only operate if the circuit between ground and the hot wires are closed by the target therefore it is advisable to have one or two ground wires in the fence to improve the chances of the target touching both hot wires and ground simultaneously.

Tru-Tek Electric Fence Energizers have two output terminals. The one marked high voltage and the other ground. The pulse is generated between these terminals. Care must be taken to earth the ground terminal properly, the better the earth, the more effective the shock. Ground conductors on the fence should also be grounded to earth at intervals. Hot wires on the fence must run through specially designed high voltage insulators and care should be taken to isolate them from any potential ground source, as a short circuit in the fence will drastically reduce the effectiveness of the electric fence. Fences should be cleared of any vegetation, which will conduct the power to earth and reduce the effectiveness of the fence.

Insulators used on an electric fence are specially designed to withstand the power generated by the energizer and are made of ultra violet resistant plastic or porcelain.

Porcelain insulators are more expensive and are usually used where there is a risk of being destroyed by fire as they can withstand enormous temperatures.

Common sense tells us that we can erect a fence using pieces of plastic piping as insulators, but it is our experience that it is well worth the extra expense to purchase the insulators as they are priced in the cent range.

The two major insulators used on normal fences are strain insulators and nail-on insulators.

Strain insulators are used at corners or at the end of wire strands. Nail-on insulators are used on supporting poles and nailed onto wooden poles with galvanized 30mm clout nails or tied to or pop riveted onto steel poles

Cable and wire

The choice of wire is wide, but we recommend 1.6 to 2mm galvanized steel wire for agricultural and security fencing and 0.71 to 1.2 mm galvanized wire for wall-top fencing.

Wires should ideally be fitted with speed tensioners, which takes the effort out of tensioning fence wires.

High voltage wire is used to get the power from the energizer to the fence. This wire has a core of galvanized binding wire and is insulated to withstand the voltages generated by the energizer.

All connections to the fence should be made using our special connecting bolt to allow you to remove the connection during faultfinding.

Ground wires must be properly grounded to ensure reliable operation of the fence

A good ground consists of 3 ground rods of at least one meter long sunk into the ground 2 meters apart and at least 4 meters away from any other electrical grounding system. Ground wires included in the fence should be grounded at intervals Remember that the better the ground the more effective the fence.

It is very well to think that the fence is powered, but there are simple ways to test for power.

The spark test

Select a suitably insulated tool, e.g. a screwdriver with a plastic handle and short circuit the hot wire to the ground wire. A spark should be heard once every second, especially if you hold the screwdriver in such a way that a spark gap of about 1mm is formed.

The grass test

Select a grass leaf of about 150mm long and hold it with the point touching the fence. The grass forms a resistor between your body and the fence. Slowly slide the grass leaf closer, reducing the resistance until you feel a slight pulse in your hand.

The right way

The above two tests are used daily in the agricultural field but even if you are brave enough to hold all sorts of things against the live fence it does not indicate much. What we need to know is how much power the fence carries. Tru-Tek manufactures a very handy low cost fence meter to do just that.

The Tru-Tek Bar-graph Meter indicates the voltage on the fence by a display of 10 light emitting diodes, each diode representing approximately one thousand volts.

The mains operated energizer is mounted to a wall with 4 screws and screwplugs.  Decide where you want to mount the unit, making sure that it is close to a 220v outlet and that the high voltage cable can be easily routed to the fence and ground rods. If you want to route the wires through the wall you must  remove the unit before drilling the holes through the wall.(Cable holes should be about 50mm above the terminals). Push the high voltage cable and earth cable through the wall from the outside. They should protrude about 100mm. Clean the last 30mm of the cable and form loops to fit between the terminal washers.

Make sure the fence is clear before applying power to the unit.

The red indicator light should come on and the unit will start pulsing after a few seconds. The fence is now charged with a high voltage pulse once a second.

The battery operated energizer is mounted to a wall with 4 screws and screwplugs.  Decide where you want to mount the unit, making sure that it is practical to put the battery close to the unit and that the high voltage cable can be easily routed to the fence and ground rods. If you want to route the wires through the wall you must  remove the unit before drilling the holes through the wall. (Cable holes should be about 50mm above the terminals). Push the high voltage cable and earth cable through the wall from the outside. They should protrude about 100mm. Clean the last 30mm of the cable and form loops to fit between the terminal washers.

Make sure the fence is clear before applying power to the unit.

The red indicator light should come on and the unit will start pulsing after a few seconds. The fence is now charged with a high voltage pulse once a second.

The Pixie is manufactured to work with an existing Tru-Tek fence energizer and monitors the voltage at the end of the fence. The unit need not be installed close to the energizer. The unit is fitted with two mounting holes on the back. Mark the mounting holes to be drilled. Drill the mounting holes using a 6mm concrete drill and with the drill set to hammer action. Insert the screw plugs, hang the unit and mark the cable holes to be drilled through the wall about 50mm above each terminal. Remove the unit and drill the cable holes using the long concrete drill. Feed the cables through the wall until they protrude about 100mm. Strip the insulation from the last 30mm and form loops to fit between the two terminal washers. Route the earth cable to the ground rods and the monitor cable to the monitor point on the fence. The monitor wire must be connected to the fence through the voltage reducer, which is supplied with the Pixie. Failing to install the voltage reducer will result in the full power of the fence entering your Pixie, which will instantly destroy the delicate electronics inside.

Connect the battery cable to the strip connector marked 12v bat on the bottom of the pixie. Making sure that the red wire goes to + and the black wire to -.

Place the battery in a suitable location and connect the battery cable to the battery, making sure that the red wire goes to the red(+) terminal and the black wire to the black(-) terminal

Connect the power supply transformer to the terminals marked TRANSFORMER 16VAC at the bottom of the Pixie. And plug the transformer into the mains outlet. Never connect the Pixie to the mains without the transformer. The transformer reduces the 220v mains to the 16v needed by the Pixie.

Select a location close to a mains outlet where routing the high voltage cable to the fence and earth rods will be practical. Mark the mounting holes using the template supplied with the unit. Drill the mounting holes using a 6mm concrete drill with the drill set to hammer action. Insert the screw plugs and drive the screws in until the bottom of the head is 5mm away from the wall. Hang the unit and mark the holes for the cables about 50mm above the terminals. Remove the unit from the wall and drill the three holes for the high voltage cable through the wall. Feed the cables from the outside until they protrude 100mm and strip the insulation from the last 30 mm. Form loops to fit around the terminals between the two washers. Hang the unit and connect the cables to the terminals. Route the earth cable to the earth rods and connect securely.

Route the cable from the terminal marked high voltage to the start of your fence. Connect the cable to the fence using a Tru-Tek line connector.

Route the cable from the terminal marked Monitor to the monitor point on the fence. Connect to the fence through the voltage reducer supplied with the unit. Failing to use the voltage reducer will cause the high voltage from the fence to be fed into the delicate electronics of the monitoring system with disastrous results not covered by the guarantee.

Connect the power supply transformer to the terminals marked TRANSFORMER 16VAC at the bottom of the Wizard. And plug the transformer into the mains outlet. Never connect the Wizard to the mains without the transformer. The transformer reduces the 220v mains to the 16v needed by the Wizard.

Warning signs have to be displayed on the fence every thirty meters anywhere along a public road. Tru-Tek can supply additional warning signs conforming to international standards at a nominal cost.

· Never install an energizer in the bedroom. The energizer makes a ticking sound almost like a large clock and will probably keep you awake.

· Ensure that your earth system is done to the minimum specifications as described in this booklet. Most problems arise from poor grounding of the earth terminals

· When tying the wall-top wire by wrapping around it, do not wrap the wire close together. Wrapping the wire in a tight coil allows moisture to be trapped between the windings. Space the windings about 1mm apart.

· It is a better practice to make all your connections on the fence with our special line connectors.

· Wall-top wires may be joined using a slipknot.

· Tru-Tek fence energizers are classed as not lethal. But they do deliver a very unpleasant electrical pulse. Always treat electricity with respect. Electrified fence energizers are not toys.

· Make sure you follow the manufacturers instructions on all the tools that you use.

· Ensure that you are supported firmly when working on top of your walls.

· You will be moving your ladder frequently, make sure it is standing firm every time you climb on it.

· Be careful with your extension cords when using such.

· Make sure your energizer is switched off before working on your fence or high voltage supply cables.

· Do not work with electricity under wet conditions.

· Do not drop cut-off pieces of wire. They will end up in somebody’s foot

Tru-Tek products have internal protection against mild power surges but cannot withstand serious surges. You are advised to purchase lightning protection plugs, which are freely available on the market. It is always advisable to unplug your system from the electrical outlet during lightning storms. Lightning damage is not covered under the guarantee.