fence lengths and conductivity
The fence / the length of the fence
Apart from the greenery, the length of the fence is also important when selecting an electric fencing energiser, since longer electric fences need fence wires with high conductivity and correspondingly more powerful energisers for proper functioning.
The fence length is simply the length of the fence, for the same fence length, multi-wire fencing systems conduct the current better than single-wire fencing systems, provided they are interconnected at regular distances.
When choosing fencing materials therefore, ensure that the material has a good conductivity: the lower the resistance, the higher the current flow.
With long fencing systems, it must be ensured that the current flow is not significantly reduced by fencing material with “poor” conductivity: the most powerful electric fencing energiser is only as powerful as the weakest link in the chain. When choosing fencing materials, ensure therefore that they have a high breaking strength and offer as little resistance as possible and that the insulators, electric fencing posts and gate handles resist high voltages. The fence lengths specified for our electric fencing energisers are theoretical maximum lengths which may be reduced by conductor material and greenery.
Longer electric fences can function only with fence wires with good conductivity. In practice, fence lengths up to approx. 120 km can be achieved with 4-wire fences and no greenery, using 2.0 mm steel wire. With single-wire versions using the same wire, the maximum possible length is reduced to 30 km already. Should you use only a plastic cord with 3 x 0.16 mm stainless steel conductors, the maximum possible fence length will be reduced to about 100m.
These figures are significantly reduced again in the presence of plant growth under the fence. It is vital to take this into account when selecting a unit and fencing materials, since only the correct choice of unit and fence conductors will ensure maximum output to the end of the fence in the case of larger or longer fencing systems.
3 basic parameters (voltage, current and resistance) of current flow in a circuit can be calculated with Ohm’s law, if at least 2 are known.
If voltage is applied to a resistor, a certain current flows through this resistor:
- low resistance = high current flow
- high resistance = low current flow
he better the conductivity of the conducting material in the fence (rope, wide tape, cord), the lower the Ohmic value.
- 0,05 Ohm/m → very good conductivity
- bis 0,5 Ohm/m → good conductivity
- bis 5,0 Ohm/m → average conductivity
- bis 15,0 Ohm/m → poor conductivity