Electric fence

We have quite a few posts that refer to us generally preferring to use on 8 joule energizers so we thought we would break it down a bit further and give a bit of extra information on the energizers themselves.

Not all energizers are equal! Thats really the point to get across. There are of course a wide range and selection of energizers and most of them are fine, just with different features. Whilst there features which are generally not necessary, there are some which are important and should be noted.

There are electric fence energizers designed specifically for agricultural purpose and then those designed for security and the smaller pet control types which we are not going into detail here with. Obviously the biggest thing is to use a security energizer for security applications! Sounds obvious but we often ( and really mean OFTEN, almost weekly!) come across energizers that are installed in security environments but are agric energizers. Now it may “appear” or sound as though the energizer has a 14 Joule ability, but the reality is the actual output at any given time is way below that. What the energizer is capable of is compensating for vegetation overgrowth and increasing its energy output to compensate only. The actual energy delivered in a shock though is probably only going to be around 5 joules (generalizing now and this is specific to different energizers) So basically these energizer units should be kept to game farm and agricultural use – NOT security fence applications.

For security applications the energizer normally provides the shock it states. They come in various energy ranges SO BE SURE as to what you are getting. The law allows a maximum of 8 Joules energy, DO NOT be impressed when the pitch involves a voltage of 10 000 (which is also the max allowed by law). This is alot to go into technically and grasp but a 5000 volt 8 joule energizer will hurt you doubly to a 10 000 volt 4 Joule energizer. This you have to take our word for!! The formula and calculations involved are complex but basically involve the time the shock is given, the amount of current and the voltage. Generally the energizers we prefer to install on electric fences are 9500 – 10 000 Volt and 8 Joule… buts it the 8 Joule thats important!

Energizers now also employ adaptive technology which allows the energizer to make adjustment for the conditions it is operating. These energizers adjust for changes on the fence which is a clever and neat function, especially if it is a big fence where more maintenance might be required if the energizer cannot make its own changes for overgrowth vegetation and so on.

The one bit of advice we should offer on any energizer is that it MUST be compliant with local laws and regulations. Around the world in United Kingdom, Australia and so on the regulations are different and hence using a security energizer designed for another country will either leave you with a energizer that doesn’t meet requirements or worse still, breaking the law. One of the major reasons we have kept our preference of energizers to NEMTEK energizers (Merlin, Stealth Druid and Wizord range) is that they pride themselves and make the effort to stay within the confines of the legal limitations – IT’S REALLY IMPORTANT to keep the owner of the property out of jail. (Th sad reality of criminal rights up for debate here!!) Consider though the main purpose of the safety regulations are not really about criminals in South Africa and crime, but rather the safety of innocent people that can as easily touch the fence such as children, pets etc.

The energizer is 50% of your fence (the rest remains in the correct wiring and earthing of the fence) so make sure you get an energizer that will fit the requirements!

Some questions to ask your installer will be:

• What energy is the energizer (8 Joule is the maximum, thats what you should go for in security installations)
• Is the energizer a security/agriculture energizer (depends on your requirements)
• Are spares readily available locally in South Africa for the energizer
• Does the energizer alarm if the wires are cut or short (believe it or not, there are really home made devices out there!)
• Does the energizer have battery back up
• Does the rated output allow for the distance of wire on your installation. (Different types of wire, different distance and rating for the energizer. An example might be an energizer is rated for 10km of 2.24mm wire but only 1.2km of stainless steel wire. On an 8 wire fence, stainless steel, this energizer would only suffice for around 300 meters of fencing! You either change the wire or the energizer!)

Hope it helps! Contact us should you have any queries, feel free to contact us.

We do get alot of questions regarding pets and electric fences, specifically dogs and cats.

For the record, we do not install “dog fences” or perimeter collar fences.

Most websites will clearly and easily state that all pets are 100% safe from an electric fence – they generally are, energizer units that comply with regulations are designed to keep pets and children safe or not to be lethal to humans.

I feel its fair however to put this properly into perspective – there needs to be separation between the size of animal and energy of a fence that is installed correctly.

We generally prefer only to install 8 joule energizers as if the intention is security, then install the maximum attainable shock! Now if you have installed an 8 Joule fence to the floor, lower strand live, the reality is your dogs will at one point or another will get to it. The good news is it will only generally happen once! For the average dogs being generally larger than Jack Russels, spaniels etc, they will generally be OK – in some cases, and this has actually happened to our own Dachshund, it may get knocked unconscious for a short period. The less the energy on the fence, the less the shock, a 4 joule energizer would probably have not knocked the dog out.

However how about the really small dogs, rabbits and electric fence? You have to equate the energy of an electric fence to what it can do. An 8 Joule shock is equivalent to dropping 8kg’s from 1 meter high – thats the easiest way of explaining it. Now would you want to do that to a Chihuahua, Toy Pom – not likely!! The reality is this amount of energy on such a small animal COULD have lethal results. On many of our 8 Joule 24 strand security fences, the guards and patrollers find dead rats OFTEN! Sure dogs aren’t rats! (Just in-case you getting upset with me). The reality though is fences can do this and to say outright that ALL dogs will be safe could be an overstatement.

We are pleased to say that none of clients have ever lost there pets, however these thoughts need to be kept in mind and if you have very small pets and are concerned for there safety, then you should consider a temporary low energy trip wire which in a few weeks months can be upgraded to full power for extra security. Another possibility is to leave the fence in low voltage mode for a while until they get shocked, not ideal for security, but that would be fine, teach them the lesson required to avoid the fence and move on.

Cats have an amazing ability to sense electrical fields and tend not to attempt passing through a fence.

So, in a nutshell, 99.9% of the time, your pets will be fine – they may get a severe shock, be stunned, howl and scream, but they will be OK, it will only happen once. For very small animals however put some thought into there safety or at least mention that you have a smaller than usual dog that is likely to access the fence so that steps can be taken to ber certain and keep the dog safe!

Love your pets!

Electric fence diagram

We decided it might be useful for those that are seeking to do there own installation on an electric fence, or repairs, and they have some form of electric or electronic experience, then an electric fence diagram might come in handy!

If you intend to do your own installation, PLEASE do take not of the warnings that come with the electric fence energizer. You will notice in the installers manual the warning “CAN LEAD TO DEATH!” Take this seriously. If you have no electrical experience or electronic experience, I strongly urge you to call someone that can assist. Familiarize yourself with the laws that surround electric fence installation – specifically power lines, warning signs, razor/barbed wire, energy, limits in distance.

To get started, ensure you have enough HT cable, braided wire (or the wire of your choice) for the actual fence, enough 6mm ferrules (1.2mm braided wire) cable ties, earth spikes.

Mount your poles first wherever you intend the fence, a wall top fence with 8mm x 75mm nail anchors, ground posts with decent concrete foundations. Keep the spacing in-between poles at 3 meters. 5 meters is becoming to far, less than 3m, lots of work! See in your mind how you are getting round corners, how the wires will run etc.

Run your wires on the poles. Try to keep the runs not longer than 30 meters before you terminate and then start a new run with its own tensioners. Tension at the corners always! Don’t turn corners then tension later.

All of your joins, connections and terminations should be done with ferrules! DO NOT just twist wire round to make your joins. The fence will work well today, but in a little while when oxidation sets in, those contacts become bad and then trouble shooting becomes the order of the day. Also keep all types of wire the same, don’t mix stainless with galvanized braid etc. Rust will set within a few months!

The electric fence diagram that I have attached is for a simple single zone series live wire and parallel earth wire system. There are mulit zone systems, series earth systems etc, but keep it simple and EFFECTIVE!

Lots of earth spikes! At least 1 by the energizer (3 is recommended) and then 1 around every 20 meters. THIS IS IMPORTANT!

You will notice on the electric fence circuit diagram that all the earths are common and joined BOTH sides – recommended for better earthing. At any stage if the fence live wire is cut, the alarm will activate or if the live comes into contact with the earth, the alarm should go go off. If the earth wire is cut, no alarm will activate. Generally when a wire is cute, they come into contact with other wires anyway causing the alarm to trigger.

If you dont have testers, then the easiest is to switch on, if the good light is good, all is probably OK. Try touching a piece of wire (attached to a DRY wooden stick) across the earth and live. As soon as the 2 wires get to a few millimetres apart, it should arc. If you touch the 2 together for 3 seconds, alarm should sound. Also try touching the live wire to something metal, like a gate. You should get the same energy or sound spark as when you did between the live and earth wire.This helps estimate that your earthing is OK

Hope the electric fence diagram helped with your installation!

Electric fence diagram

So you’ve decided its time to install or upgrade your fence. The simplest thing, get a few quotes and see where to from there. Something you should be considering though is what wire do YOU want, not what does the installer want to use! Installers will generally give a quote on what they believe is suitable OR which one is likely to win the quote.

The critical components that involve wire:
• Longevity – how long will the wire last before it requires replacement
• Resistance – how much can be used before a second (or more energizer) is required. High resistance is bad!
• Strength – The strength of the wire to resist breaks and damage

Corrosion resistance is referred to often in this article – IT IS ONLY FOR THE PURPOSE OF REFERENCE as there are multiple factors such as different metals, electrolysis that all influence this!

Stranded galvanised (generally 1.2mm but others are available)

By far the most popular wire used on electric fences and for good reason. It is easily worked with, tough and its life span is not bad. The cost saving on this wire the winning factor more than anything else. The resistance of the wire is around 175 ohms per Km making it the second best wire for home / industrial applications available in terms of running distance. Expect corrosion maintenance around 5 years, replacing around 7-10 years (varies from installation to installation and what connectors, tensioners are used influences also)

Should be used on:
Home installations
Small industrial applications
OK for 24 strand applications on small plots (within reason)
Small complex applications

Should NOT be used on:
Game fences – runs to long and does not have the strength
Coastal areas where corrosion is an issue
Not large plots of 24 strand. The resistance of wire soon catches up and a second energizer required)

Galvanised 2.24mm solid wire

Accepted as the daddy of all wires! It is thick high tensile wire that can be difficult to work with but the benefits of a very solid, strong fence easily out-way the work and cost! The resistance is around 50 ohms meaning it can cover more than TRIPLE the distance of 1.2mm galvinised strand. Corrosion maintenance can be expected around 10 years with replacement around 15 – 20 years. It is the most expensive of the wires, however the strength, low resistance sometimes make it the only choice!

Should be used on:
Game fence installations – favourable running distance and very strong
Large plot installations
High security applications industrial/commercial

Should NOT be used on:
Wall top installations – these brackets are not designed for this wire that exerts extreme force (it is possible to make custom brackets, however expect a very bulky look!)
Coastal applications – corrosion

Stainless steel wires

A popular wire used for domestic installations. Its corrosion resistance ability will probably last your lifetime (different grades available and location an issue as well as joiners etc used). Its big catch…. Resistance of the wire. This is around 1000 – 700 ohms per km meaning it can only cover around one fifth of the distance of strand 1.2mm. The cost of wire also plays a part here as cost per meter.

Should be used on:
Domestic applications
Coastal applications – a must use for coastal due to corrosion

Should NOT be used on:
Game fence – resistance on a 24 strand fence 1.6mm stainless would mean an energizer every 160 meters to keep in energizer parameters approximately!)
Long distance domestic applications – an 8 stand fence of 1.2mm stainless could only do around 250 meters of total fencing, around the size of a normal 1400m stand

Aluminium wire

The lowest resistance of all! At around 27 ohms per km, this wire can do almost double of 2.24mm and around 5 times the distance of 1.2mm stand. Disadvantages are it is far easier cut than any of the others and stretched making is security ability challenged against any of the other wires. In terms of longevity, once gain would probably last your lifetime (again variables involved)

Should be used on:
Coastal applications – ideal to resist corrosion and this is really where this wire features. Ideal for long runs on game (coast only) etc, only pity about the strength which will require break maintenance. Still better than replacing it in 2 years though!
Industrial applications are suited (should consider 2.24mm solid though for strength, )
Large plots
Complex applications

Should NOT be used on:
Very short runs (energizer impedance issues in some cases)
High security applications where stretching could be an issue (this one needs to be weighed against distance versus security and cost!)

Hope that sheds a little light (might have confused even more) but still if in doubt, ask for the differences and why the one chosen is the one that is best… should NOT just be about the cost always. YES I know cost helps but for a game farm that will be around for the next 80 years, maintenance and replacement is a huge issue and should be factored in.

Electric fencing correctly installed on the property, does it really make a difference? So many stories circulate about how electric fences are circumvented by criminals that many peoples first question is do they really work?

Lets take a logical look at electric fencing and what it could really do for your property, correctly installed, may be an operative word also for this article however. Stories involve all sorts of wonderful achievements, toilet roll innards to bypass earth loops, blankets thrown over and then climb over the blanket, wire cutting, wire bypassing, wire separation and the list can go on.

Peoples general outlook on an electric fence is therefore the VISUAL deterrent of the electric fence is what counts! WRONG! Yes the visual deterrent of electric fencing is part of the equation but should NOT make up the whole equation. Many of the stories of how criminals get through electric fencing are true to a degree, what is often left out is that the fence was not correctly installed or in a bad condition.

I challenge anyone to try some of these, with a full 8 joule correctly installed fence. Throw a blanket over the fence and try to climb that . The reality is that the alarm should go of if the wires touched and further to that, I assure you there are very blankets that will protect you from being shocked through the blanket!

Cutting wires…. Again, you don’t have to cut them but try to (a working 8 joule fence). There are not many tools available on the market that will protect you from a shock through insulated pliers and the ones that are generally pretty expensive. Fences do get cut, they are either off or very low power fences.

Bypassing electric fencing – OK, now this one is out of the movies. Yes it might of happened at some point, but this is not an occurrence that is likely to EVER happen to you or your neighbours. Technically the person would have to have a fair amount of knowledge, some fairly expensive tools and a fair amount of time to achieve this feat.

Wire separation and digging under a fence. Now here there is truth to getting through electric fencing! These are currently the most popular ways of getting through… but they can be avoided! Once again correctly installed and a sufficient amount of earth loops and ground loops makes this VERY difficult to achieve without setting off the alarm. A method we heard of was to use toilet roll formers. Out of curiosity of course we had to give this bash! We set a section of fence with a 1 joule energizer and gave this a try (1 joule makes it like a game, you nervous of the shock, but it really is nothing) 3 people gave this a try, every one of them got a shock at some point and more than one and the alarm was activated every time but once. Now 3 shocks from a 8 joule energizer, I really have a problem believing this story! I suspect the fence involved in this criminal caper had a few issues!

Crime in South Africa is out of control, everyone knows that (except maybe our well protected government). The worst of it is that it is violent crime. The first line of defence is your property boundary and therefore this is the place to start. Makes sense doesn’t it? If you can stop them coming through the boundary, perfect, if you can’t stop them then at least know they are there. A well installed electric fence with no holes, high shock value will either stop them, or at the very least set of an alarm. Criminals are not likely to continue if they believe that you are aware of there presence as element of surprise for them is important. Remove the element of surprise at the boundary. Personally our house alarm is never activated anymore, not interested in that, (if the house alarm has gone off, they are already in the house, too late) I want to know when they are on the property or boundary, it gives me better control of the outcome!

Fences that are easy to get over – switched off, trees overhanging and not covered, corners that allow climbing, posts that allow climbing, no earth loops, gates incorrectly connected, prefab walls, with a wall top only, very low fences like 3 wire.

Electric fencing installed correctly is the best available first line of defence, any better is probably not legal

24 strand 2.24 mm on a wall next to open vlei

24 strand on palisade 1.2mm. Nice, the palisade acts as a huge earth

Aha!! We new this would grab your attention – possibly for the wrong reasons though?

Compromising on an electric fence will lead to a false sense of security which may be worse than no security! (It is better to be aware of your surrounds rather than believe you are fine and not aware!)

To often we see a 3 strand fence straight up. It would take 3 seconds to jump over. Electric fences are installed with NO EARTH SPIKES. A tragedy!! A R40 000 fence installed using a 4 joule energizer only to save maybe R800 to R1000. A 4 joule energizer produces exactly half of an 8 joule (logical) Why spend R40 000 on a small complex fence only to provide it with half the legal power? This does not make sense.

Obviously everyone is concerned about costs but investigate the options of different brackets and types of wire without compromising the actual fence ability. If there are no earth spikes in the quote, run a mile! Cutting out cost of R500 to win the quote and leave the fence very limited!

I honestly do not suggest a cheap energizer as you really do want to deliver all that is possible. Request a 8 joule energizer. A quote is often made acceptable by cost cutting everything, the earth spikes (only use 1 instead of 6), a low joule energizer, round bar wall tops instead of square tube (square tube much stronger)

Of course when budget really is more of the issue, we understand. A 4 joule energizer is certainly better than NONE! A well installed 5 strand 4 joule energizer I would take over nothing any day… really. JUST NEVER COMPROMISE ON THE EARTH SPIKES!!! This will assist you get an electric fence when possibly you thought it would not be possible.

I guess the real emphasis here is if you are spending a large amount R10 000 and above, saving 800 on a energizer I would not recommend.

Be very cautious of accepting anyone off the street to install the fence. A recent client spent a further R5000 with us re doing all the corner brackets/wiring and adding extra fence – the fence had fallen down in the FIRST WEEK of installation. A friend installed a fence for another client. We spent 2 days redoing HT cables, jumpers, earth loops, the entire earthing of the system and weak points (you could still jump over the gate, there was ample space to get through!) Quite simply is what they had was a FALSE SENSE OF SECURITY due the badly installed electric fence.

The worst misconception that finally comes from a badly installed fence is that it is not worth fixing when cut, broken, damaged as it never really protected the property anyway! The reason it didn’t protect the property was IT WAS BADLY INSTALLED or MAINTAINED. If done correctly, cutting through a fence without getting shocked or setting of the alarm is very unlikely. Have it done correctly first time round!

There is only one way to do any electric fence, security, animal control, game fencing, properly and it is with correct earthing.

Regrettably 9 out 10 security fences looked at for repairs, are way off correctly earthed ranging from completely incompetent to could have possibly done better. Completely incorrect is unfortunately the most common. Many fencing companies now will not even repair a fence unless they installed it – basically having to tell a client that there fence was badly installed often does not go down well

Energizer manafacturers recommend at least 3 earth spikes spaced at 1m at or at least near the energizer itself. Now, already most installations that i see only have one and many none with one ground spike being at the fence. Lets face it, why would the energizer manafacturers waste time printing this if it wasn’t required or neccessary?? IT IS REQUIRED AND IS NECCESSARY!

Energizers work on very basic electrical theory that in order to get a shock, a circuit should be made. Hence, if you touch only a live wire, the circuit needs to be made through the live wire, through the body to ground and then back to the energizer to complete the circuit. If there are two few earth spikes, then the part of “through the ground and back to the energizer” FAILS!

Its really sad to see an expensive and full installation (especially on game fence) that is incorrectly or badly earthed, sometimes only with a few earth spikes. It would have been easier on the pocket to have done a really cheap installation with small energizers, lower wire quality but correct earthing. You would be achieving in principle exactly the same shock value! In one installation a game fence was seen to have 10 earth spikes (to few energizers which compounded even further to bad game fence) spread over a 10km distance. Thats one earth spike per km and NONE at the energizer. Since as i am not mentioning the installer, i’ll say it “THEY WERE COMPLETELY RIPPED OFF!” Fortunately the repair and correction was not to severe and the fence easily broken to correct. Basically this fence should have had in the region of 100 earth spikes (one per 100m) and 3 for each energizer installed. For the installation in this case, 103 earth spikes and NOT 10. (the ground in the area was suitable to spread out)

One factor that is not that easy to get around is very dry areas. Dry soil conditions and types does affect the earthing ability of a region which becomes problematic for fence installations. Solutions do vary but the most obvious is more earth spikes. They are not cheap, at around R25 to R60 each, but compromising on a large installation, well laid out, for a few earth spikes is really just wasting money at the same time.

If your fence is not earthed at around 30m intervals (or even better less), then it is not as effective as it could be and should probably get it checked out!