McCallum Made Electric Fence Tester

How to test electric netting using an electric fence tester

The first thing to note is that an electric netting fence operates at much higher voltages than a normal household electric circuit. For this reason you cannot use a normal voltmeter to test an electric netting fence. You will need a specific electric fence tester for this purpose.

By way of background information, an electric fence energiser puts out about 7,500V to 8,500V depending on the brand and the model. However, as this charge travels through the earth and the wire (more on this later) the effective voltage drops. The minimum charge you will need to achieve in order to deter a predator is usually about 3,000V. So don’t be too worried if your fence drops from 8,000V measured at the energiser to 4,000V along the fence line – that reduced amount will still be sufficient to deliver a strong electric zap.

Let’s also think about what the electric fence is trying to do – the electric fence energiser generates a “zap”, the zap travels from the energiser along the red cable to the electric net. Most zaps will dissipate at this point as there is nowhere else for it to go. However, if a zap is lucky then an animal is touching the net with its body. The zap travels through the body of the animal and into the ground on which it is standing. The zap then transmits back through the ground, to the earth stake which is attached to the green cable attached to the energiser. The earth stake is a critical part of system. Ground conductivity varies due to geology and moisture content, especially in upper soils. Longer earth stakes tap into less changeable conditions so are more effective. Multiple earth stakes will always result in better fence voltage. The zap returning to the earth stake completes circuit of electricity, creates the shock which the animal feels as a muscle contraction creating fear and a desire to not touch the net again.

Therefore in order for your fence to work all of these links must work properly – the energiser, the red cable, the fence, the ground, the earth stake and the green cable. The only way to test your fence is to test each of these links in turn to discover the “missing” link.

McCallum Made Electric Fence Tester


Step 1 – Test the energiser.

The first and most obvious thing to test is the energiser. Turn the energiser off, detach it from the fence, attach the green cable to the earth probe on the tester and red cable fence to fence probe and the and turn the energiser back on. If the energiser is working correctly then you should get a reading of 7.5 (7500V) or higher. If you have a reading under 7.0, then you probably have a faulty energiser. The nature of the fault will depend on the type of energiser and can be all sorts of things from a dead battery to faulty transistors. Fixing the energiser is best left to professionals. (you could take it a stage back and use the tester across the terminals, then re attach the leads and repeat. Sometimes leads are duff)


Step 2. Test your electric net.

Assuming your energiser has passed Step 1, it is now time to fence your electric net. Generally speaking, an electric net is just a collection of wires so it is unlikely that the wires are not conducting properly (unless they are cut). You can test this by placing your entire net on a non-conductive surface.

Turn off the energiser. Detach the red cable from the tester and attach it to the clip at the end of the electric net. The green cable should remain attached to the fence tester. Touch the fence tester to the electric net (as far as practical from the point where the red cable is attached) and see what reading you get. You should get quite a high reading here – probably around 90% of the reading you got when testing the energiser by itself.

If you get a significantly lower reading, then either the surface you have placed the net on is conductive, the energiser is having trouble “throwing” the charge (either because the energiser has a fault or is not sufficiently powerful), or the electric net has faulty wiring.

However, if your energiser has a rating of 2.5km (0.25 Output Joules) or more, and you are working with a single net placed on a non-conductive surface you should have no trouble.


Step 3. Test your set up.

If you have come this far then we know two things – the energiser is putting out sufficient charge and the electric net is conducting electricity.

So now it is time to go out in the garden and erect your net. For testing purposes, choose a nice level space, mow the grass as short as practical and set up the net in a nice regular pattern (a square or rectangle). Attach guy ropes to the four corners and make sure the green horizontal wires do not touch the grass or ground (the black bottom wire can run along the ground all the way around). Hammer the earth stake into the ground. The deeper the earth stake is in the ground, the more surface area of the stake will be in contact with the soil and therefore the better its conductivity. So please insert the stake as far as practical into the earth. The limiting factor here is basically your ability to get it back out again.

Now attach the energiser to the fence – red cable to the clip on the electric net and green cable to the earth stake. Turn the energiser on. Put the prong of the tester into the ground and touch the top of the tester to the fence. Do this at multiple different points along the length of the fence – say ever 10m or so.

If you get readings of over 3.5 (3500V) all the way around then your fence works fine. If your reading is lower than this then you have 3 possible problems – grass / earth or other conductive materials are touching the net (earth leakage), there is not enough moisture in the ground for the electricity to travel through, or inefficient earth stake. Voltage on your earth stake (getting a zap) indicates an ineffective earth.

If the netting is touching grass / earth / branches then this is easy to fix by removing the problem or repositioning the fence. Over undulating ground it can be difficult to keep all of the live wires from drooping and touching ground, adding in additional posts can help with is. Check the metal pins on the netting posts, sometimes the net can get caught up shorting the fence. If there is not enough moisture in the ground then this can be a problem that is difficult to overcome, although it should not be a big problem with electric netting as the distance between the net and the energiser is not great. If your earth stake is rusty, a clean one will work far better as will a bigger earth stake as it has more surface area. Adding in extra earth stakes and connecting them to first will help

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