Pin lock insulators on cattle fence
You must use post insulators on all live wires on posts except on fibreglass or creosote treated hardwood posts or as described in the section on fence posts.
If you are putting the insulators on steel posts or green trees then they must be of good quality.
Strainer Insulators
Note the correct use of the strainer knot around the insulator.
Porcelain or good quality plastic insulators, oblong or oval shaped and about 75 mm long, are tied to the strainer posts with 3.3 mm or 2.5 mm wire. If you attach these insulators correctly to the posts they can withstand the strain on the wires. Install them so they are compressed when you strain the wire, so that the wires don’t tend to pull them apart and so they don’t break readily if an animal hits the fence.
Porcelain insulators that are highly glazed and free from cracks are the best ones to use for permanent line posts and stand-off wires. They can withstand the heat of a grass fire. However, they are expensive and can be difficult to put on.
If you look carefully at some insulators you’ll see a sloping surface designed to let moisture run down and off.
You can also use specially produced tubular plastic that has been reinforced with steel for insulating strainers and corner posts. However, some plastic bullnose insulators are cheap and nasty. The wires cut through the plastic internally and touch, giving no insulation, but when you inspect them outwardly they still look quite ok.
You can use circular shaped porcelain insulators on corner posts or anywhere the fence changes direction. The wire is free to move around these wheels so the fence wires have a continuous strain around the corners.
Automatic Alarms and Fence Monitors
Automatic alarms include those that ring a bell or turn on a light when some fault occurs. They can be adjusted for sensitivity to voltage drop.
There are two main types of alarm:
- Line voltage monitor at, or close to, the energiser. It indicates excessive leakage in the fence, faulty earth. faulty energiser and power failure to the energiser.
- Fence voltage monitor at the end of individual sections. It indicates which particular section of the fence is faulty.
However, both types are quite expensive.
Gallagher’s Smart. PowerTM energisers have internal alarms that monitor the fence and report problems using remote communication technology. The alarms are for output voltage, fence voltage, output energy, stored energy and earth voltage.
