Bushfire
The possibility of an electric fence starting a fire is very slight and the possibility is lessened if you connect your fence to a low power terminal of the energiser during the danger period or turn the unit off during daylight hours. In extremely hot, dry conditions stock are more likely to move at night and not in the day. In some areas the risk of fire would be non-existent. It’s up to you to decide on the risk and act accordingly.
Lightning
It can help to have the top wire of the fence earthed. Never touch an electric fence or any other fence during a thunderstorm. Lightning strikes during thunderstorms are common. You may have plenty of carefully insulated fence wires on your property. These don’t allow the current to leak but carry it straight back to the energiser. If the fence is struck by lightning the wires carry the extra electrical energy back to the energiser. In a flash! It is possible to install a lightning diverter, in which case the separate earth system of the diverter must be at least as good as the earth system of the energiser. The idea is that the lightning is diverted to the earth of the diverter before it gets to the energiser. This does not protect the energiser from a direct hit. Apart from the obvious fire risk, this will almost certainly damage or destroy your energiser. Disconnect the energiser from the fence and unplug it from the mains supply for protection during electrical storms. Modern lightning diverters use a common earth system; energiser and diverter both earth to a common earth stake system but the system doesn’t protect from a direct hit or from a surge from the 240 volt side. You can use a power surge protector for the latter.
Power lines
Seek the advice of your power authority before you run a pulsed wire parallel to or below overhead power transmission lines. If a power line falls onto your fence, thousands of volts leak onto your wires and your whole system becomes lethal. Don’t run the fence parallel and close to high voltage power lines. Avoid the possibility of induced current in your system.
Phone lines
Build your system so there is no chance of a pulsed wire contacting phone lines, radio or television aerial or any part of a building. Otherwise the appliances or the building can give people a nasty shock.
Earthing
Never use any part of your household wiring or plumbing as an earth for an electric fence. Otherwise, your family and others might become part of the electric circuit! For example, one farmer received shocks through his shower because the drain was a better earth than the water pipe that he was using as an earth connection.
Another problem with household wiring is that if there is a mains power fault to earth, mains voltage can be transmitted into the fence system.
If the earth wire touches the building, the same shock can occur under certain circumstances. For example, you can get an electric shock if the earth wire is broken or if there is a bad earth circuit on the fence.
Make sure the earth for your electric fence is well clear of any mains earth stakes. For example, have a distance of 10 m between the fence earth stakes and the mains earth.
Weather protection
Mains powered energisers should be protected in a box or, preferably, a shed. This is a simple safety measure.
Output leads
All the output leads from the energiser to the fence should be made of insulated galvanised wire. This includes the earth connection. Make sure you have a drip-loop where the wires enter the building so water doesn’t run down the wire to the energiser.
It is good practice to have leadout wire that is the same diameter as the wires in the electric fence. For example use 2.5 mm gauge wire in the output leads to make sure that you deliver maximum voltage to a fence using 2.5 mm wire.
Aluminium wire is also suitable but it is expensive and so rarely used.
Take care so the output wires can never come into contact with the building, especially if it is made of iron, or if it is used to house flammable materials. If the electrified wire touches the building the whole structure can deliver a powerful shock, or cause dangerous sparks.
Keep the output wire well clear of any power lines or water pipes around your home.
Take care when you attach and clip the insulated wire. If the wire is accidentally scratched the insulation may be damaged enough to cause a short circuit of the high voltage current.
