PERMANENT FENCE CONSTRUCTION
Why fence construction is important
Fence wire
Wire tension
Wire resistance
Wire connections
Strainer posts
High strain insulators
Fence posts and insulator options
Wood post insulators
Gateways

WHY FENCE CONSTRUCTION IS IMPORTANT
There are three main reasons for emphasising the need for good quality electric fence construction.

To provide an effective barrier.
Electric fences do not need the same strength of construction as conventional fences because animal control is achieved by psychological rather than physical means.
Permanent fences, and especially fencing against large animals, must be soundly constructed to withstand the rigours of use.

To minimise power leakage.
Electricity will always seek the shortest route to ground.
If a fence system is poorly insulated the energy from the energiser is wasted.
There is also a risk of insufficient voltage on the fence for animal control.

To maximise conductivity
There is little point in connecting a high power energiser to a fence system constructed of wire with poor conductivity.
The energiser will effectively be choked the energy will not transfer as an effective shock to the animal.
TO remedy conditions in paragraphs 2 and 3:
Read section on lead-out wire carefully [section 4].
Always make wire connections using joint clamps.
Back to top

FENCE WIRE
Electric fences should be constructed using a minimum 2.5mm [12½g] high tensile galvanised wire.
NEVER electrify barbed wire.
Back to top

WIRE TENSION
Fence wire on electric fences should be tensioned in the range 2.5 - 9.9kN = 25 -90kg = 55 - 200lbs
A higher tension is recommended where wild animals may come in contact with the fence.
Tensioning is easily achieved using a line wire strainer.
Simply fit to the wire and tighten with a spanner [or strainer handle].
Back to top

This means that:
The longer the fence wire the greater the resistance.
Double the length and you double the resistance.
The smaller the diameter the greater the resistance
As shown in the table 2.5mm [12½g] wire has 2½ times the resistance at 4.0,, [8g] wire.
Two wires connected in parallel have half the resistance of a single wire.
Aluminium wire has a resistance one sixth that of steel wire.
Back to top

WIRE CONNECTIONS
Wire joints are a major cause of power leakage.
There is only one rule you should apply in all circumstances:
All live wires should be clamped to eliminate arcing and subsequent loss of voltage.
Particular care should be observed when joining:
dissimilar metals high risk of electrolytic corrosion
aluminium wire must be clamped tightly because of the high resistance aluminium oxide coating.
Back to top

. STRAINER POSTS
Because strainer posts support the tension on the fence wire, they must be strong, properly rammed into the ground and well braced.
The same applies to gate posts and corner posts.
To run fence wire round a corner post.use wrap-around insulator as shown below, or use strain insulator as shown below.
Back to top

FENCE POST AND INSULATOR OPTIONS [on left]
Good quality insulation is very important to prevent power leakage from the fence wire to ground.
A normal wooden fence post can act as a conductor when wet, especially when high power energisers are involved.
Back to top
WOOD POST INSULATORS [on right]
Pinlock Insulator 'W' Type Insulator
Staple On Insulator

Not recommended for use with high VOLTAGE energisers because of possible power leakage to ground via the staple and fence post.
Back to top

GATEWAYS

When buried in soil and subject to voltages typical of electrical fences, it deteriorates within a few years and the fence becomes very effectively earthed. The copper conductor will also cause serious corrosion problems with connected to galvanised wire

Back to top