For a mob grazing system you need easily accessible power in each field. The best way to do this is to surround each existing field with a permanent or semi-permanent electric fence. It is possible but not recommended to run electric fence together with existing barbed fencing. If the barbed wire becomes live through a fault it can be very dangerous for animal if they become tangled. However if every care is taken to insure this doesn’t happen it can be the cheapest and easiest way to run electric wire.
At is point I would stress that for the purpose of mob grazing it is not a good idea to divide fields (unless very large) up into permanent fixed paddocks….having flexibility within existing fields is key to success so you can change paddock sizes and orientation throughout the season depending on herd-size and grass growth.
The recommended technique for a permanent electric fence is quite labour intensive, expensive and tricky to maintain. It involves heavy strainer posts, high tensile wire put under a heavy strain and every component as to be strong enough to withstand that strain. Needless to say all these components add up and are all expensive. Another down side is that if a strainer post for example needs replacing (which inevitably they will at some stage) it is a bigger job than putting it in in the first place and because the whole system is under such tension it can be dangerous and is difficult to work with. I have a cheap very effective easy maintained simple system that is nothing extraordinary but it is pared back to the essentials without compromising on functionality.
The main change is the wire used. High tensile wire total over kill for this purpose, all the wire needs to be is solid, easy to work and galvanised, so it carries a good current and you can see if it is broken or damaged.
This is the stuff I use. It is soft solid steel galvanised wire (not high tensile) It is sold as tying wire and measured by weight rather than length but there is around 100m in every roll and costs €6.
I love it because you can hold it in one hand open the three ties with a piers tie off the inside end at your starting point straining insulator and start walking letting it uncoil from the inside out. Stretch it out just by pulling it manually (do not use any mechanical straining tools). To finish loop it through your end staining insulator and pull any slack out and that’s it! No fancy fencing tools or help required.
Going a step further and using polywire as part of your permanent infrastructure wire is not a good idea because it is very difficult to find a fault in the line. Also polywire does not carry current well over long distance.
To start and finish your strain you need plastic egg insultors, just tie one end with a short length of wire to the post and tie what will be your live wire though the other hole.
Posts are the next major thing to consider. Because you are not using high tensile wire the pressure on the posts is minimal so I use the cheapest post with a bit of bulk 5ft spilt posts which can be as cheap as €1.40
I have no data to support this claim but through my short experience I have found the split posts resist rot for longer that the round ones. This may be due to seasoning better or soaking in the preservative better but it appears to be the case. They are also cheaper, easier to handle and easier to drive into the ground.
To set up your fence section: drive the first and last post with a mallet or sledge or whatever your preferred method (these posts are to act as strainers, the wire between them should be in a straight line with a few exceptions like external corners over short strains). Then tie on the insulators and stretch the wire between them. This distance should be no longer than two reels of wire or 200m. If you do need to go further set up another egg insulator on your last post at 200m and start another independent strain. Connect the two sections of live wire with some insulated wire around the post.
Once you have your wire stained you can place your supporting posts every 20ms or so. The function of these posts is not to take strain but to support the wire and hold it at the correct height above the ground (approx 30inches). The lay of the land may dictate where this posts go as you will need a support at the crest and trough of every rise and fall in the ground along the line. With some extra thought you can be clever and have one of these posts at points where you plan the divide the field with polywire in the future but this can be altered quite easily later on as you get to grips with your system.
There a two options here both cost around the same, one is to use another spilt post with a screw in insulator, the other is to use a pigtail step-in post. I like to use a spilt post every 20m – 30m and if the wire need to be propped up or down in between I use a pigtail post. It is not possible to use the pigtail post option if you wish to have a double stranded fence.
Another insulation method is to use light gauge ½ inch water pipe cut into short lengths and stapled on. This is very cheap but does require a bit more planning as all the insulators have to be threaded on to the wire before it is tied to the strainer post. This method can also be used to get wire stained around an external corner.
On an internal corner strainer a single egg insulator can be shared.
Tip: Try to design your fence so that you have as few joints in the wire as possible, everywhere the wire is tied the fence loses current. One way to do this is when tying wire to an egg insulator it is good practice to leave about 2ft of extra wire, if you ever need to run a second lower wire this can be used to connect the two strands so there is one joint rather than two!
The final thing to consider are the gates: The best way to do a gate is quite a bit of work.
It involves digging a trench 2ft deep across the gateway and burying a length of insulated wire in ducting. This wire is connected to the live wire at the “hinge” end of the gate travels underground and then connected to the closing catch of the gate. This means when the gate is open it itself is not live but the power circuit of live wire around the field is not broken.
Where the ducting comes out of the ground it needs to be turned down and finished (like pictured) to prevent it filling with water.
The other option is to connect the power straight across the gate so that when the gate is open it itself is still live (this means it will earth if left on the ground) and it will also break the circuit so all the fence past the gate will no longer be live. This can used to an advantage if you design your fence that you can turn of the power in that field by unhooking the gate so it works like a switch. This can be handy if you need to connect a dividing polywire or do some maintenance without having to walk back to switch off the mains. In this case it is a good idea to have somewhere to hook the gate so it is not earthing on the ground.
For the gate itself you can buy especial electric fencing spring gate of about €15 or you can buy just an insulated handle with a small spring in it for about €5 and use a piece of fencing wire “hinged” on a screw-in insulator.
Another cheaper option (that can be a bit fiddly but handy of a gate that is not used very often) is to make a handle from a 1ft piece of water pipe with fencing wire fed though it a fashioned into a latch and in such a way that the pipe doesn’t slide.
For the insulated wire buy the proper stuff designed for electric fencing. It is galvanised wire with a double insulated covering. If you use copper household wire it will react with the galvanised wire and both will corrode, oxidise and reduce the current.
Once your field edge is surrounded with your permanent fence you can divide it anyway you choose with great flexibility using polywire. There are different brands and types of polywire, get the strongest one with the most wires running through it available.
Avoid polytape which is a flat ribbon with wires running in it. (it is designed for horse so that it is more visible) It is too bulky of the reels and it tends to catch in the wind and get flexed too much and the wires break so it stops carrying current. Polyrope is very thick version of polywire also designed for extra visibility but it is again too bulk for the reels.
Buy a reel for every roll of polywire. The one pictured is a cheaper one about €12. You can buy 3:1 geared ones the hold up to three rolls of polywire for €60 if you have very long fields to divide but I have found the cheaper simple type more than adequate. All it has to have is a way to reel up the wire, lock in postion and a way to fasten on to the permanent fence.
You need at least three of these for every group of animals you are mob grazing: one as a back fence, one as a header fence and one for the next paddocks header fence.
Temporary fencing posts are limited in Ireland to plastic step-in posts or insulated steel pigtail posts. Both are useful. The steel ones are much stronger and last much longer but they are limited to carrying one wire at a fixed height of 30 inches. The plastic ones do get broken and get even more brittle with age and uv light exposure but they have the advantage of carrying multiple strands and many height options which is useful for sheep, calves or short legged cattle!
- Shopping list
- 5ft spilt posts
- Pig tail step-in posts
- Plastic step-in posts
- Rolls of galvanised tying wire
- Double insulated wire
- Screw in insulators
- Egg insulators
- Insulated wire gate handles
- Some light gauge 1/2 inch water pipe (if needed)
- Staples (if needed)
- Polywire + Reels
- Tools Needed
- Post driving tool (mallet, sledge)