Otter fences

Simple polywire fence

Simple polywire electric fences consist of 2-4 live conductors tensioned between electric fence posts with each row positioned approximately 10 cm apart.

Effect

In practice, simple polywire fence with 2 wires set at intervals of 10 cm and 25 cm provides an effective defense. An even higher level of protection is achieved by using 4 wires.

Pros and cons:

Benefits of this type of fence include a low initial outlay, ease of assembly and effective deterrence. There is no danger of amphibians becoming entangled in the wires. They can still reach the pond unhindered.

A disadvantage of this fence is the maintenance. The electric fence must remain free of any disturbances in order to function properly. Overgrown vegetation, grasses or bushes that come into contact with the fence will create a connection to the ground and thus complete a circuit in the electric fence system. This results in a lower fence voltage and a reduced deterrent effect. For this reason the grass beneath the wire fence should be regularly mowed and bushes and shrubs trimmed. Extreme weather conditions such as snow or flooding can reduce the effectiveness of the electric fence. However, even this situation can be dealt with by installing decoupling resistors. It should be further noted that the polywire fence is only suitable for use on areas of flat ground. Otters can easily slip under the fence where there are hollows or depressions in the ground.

Conclusion:

If the advice given here is followed, then simple polywire fences are certainly a secure and simple method.

Assembly:

Electric-fence.co.uk recommends using 4-row polywire electric fence for an optimal effect.

The basic equipment needed for any electric fence system are: energiser, posts, insulators, fence and ground connection cable, conducting material, warning sign, grounding stakes and lead out cables. Get all materials ready and start by first positioning the fence posts.

Plastic posts or fiebreglass posts are usually used for otter fences. These are easy to install and remove, mechanically durable and UV-stable. (Item no. 44452) The fiebreglass posts (Item no. 42555 / 42556) are extremely flexible with freely adjustable insulators and are best set to heights of about 10, 20, 30 and 40 cm.

If you wish to put a gate into your electric fence or include corners in your plan, then you should use a permanent fence post at these points such as the Allround Metal Post (Item no. 44386) so as to ensure the fence remains stable. The insulators are attached to these using metric screw threads (Item no. 44327) at four heights at which the conducting material will run.

Polywire is a particularly suitable conducting material, providing very high conductance thanks to the use of high-quality stainless steel and copper. (Item no.: 42405, 44645, 44509) Feed the wire through the eyelets of your flexible posts and through the insulators and mount these at the start and end of the fence. To prevent any loss of current, do not put any knots in your conducting material. Instead, use connectors (e.g. Item no. 44684, 44751) to hold the wire in place. Connectors will make it easier to re-tension the fence later on, and will also protect the conducting material.

As with any electric fence, stranded wire fences need a good grounding connection. For this reason, a grounding stake should be used to provide a route for the electricity back to the energiser (Item no. 44219, 44375) If the ground conditions are particularly poor, e.g. sandy, dry soil, it may be necessary to use several ground rods. Connect these together using a highly conductive corrosion-resistant wire (ideally galvanised steel wire or lead out cable e.g. Item no. 32601).

Wild animals like otters are considered "difficult to deal with". High-performance energisers at around 4,000 V are usually used. However, otters are very careful animals and will usually touch the electric polywire using their sensitive noses and paws. As such, 3,000 volts is sufficient. The 230 V Energiser "NV 1200" (Item no. 41810) meets this requirement. The "NV 1200" is very easy to use and a great choice for those new to electric fences. If it's a very large pond that you need to protect, then we recommend the slightly more powerful "Extra SAFE 230 V" (item no. 41820). The "Extra SAFE 230 V" is mains powered and provides the required voltage even along lengthy sections of fence and where there is light vegetation.

Insurers recommend installing a ground fault circuit breaker (Item no. 48015) when using mains energisers in the home, yard or garden. This is placed between the energiser and plug socket. The energiser is instantly turned off the moment any fault currents are detected. Fault currents may be caused by defective cable insulators or moisture damage. Using a ground fault circuit breaker will avoid any accidents involving electricity.

If no mains connection is available, then choose the 12 V battery energiser "Green Energy" (item no. 44186). This is fitted with modern battery saving technology and automatically adapts itself to the condition of your fence. As well as being battery powered, this energiser also has connections for mains and solar power supplies - making it extremely flexible. For longer fences or areas with a lot of vegetation, we recommend the "AV 6500" battery energiser (Item no. 42060). The "AV 6500" is very powerful, can be easily attached by crocodile clips and comes with an indicator light so that you can quickly see that the fence is in working order.

If you only need to enclose a small area, we recommend the 9 V battery energiser "BV 3900" (item no. 42030, 42031).

Available power supplies for battery powered energisers are either the 12 V wet battery (Item no. 34461), which is the same as a car battery, or a solar panel (item no. 44412, 44465). For the 9 V energiser we recommend the 9 V /130 Ah dry battery (Item no. 34420).

To ensure clean conductive connections in your electric fence you should use a lead out and fence connector cable (item no. 44300 and 44407) as well as connectors (Item no. 44619). (Lead out and fence connector cables are included with the "AV6500").

Using a fence tester you can quickly and reliably determine how well your fence system is working. Digital testers are especially convenient. (Item no. 44863). To ensure an effective deterrent, the operating voltage should be at least 3,000 V.

For safety purposes, lightning protection equipment should also be installed (Item no. 44755). This will prevent lightning strikes from affecting your energiser during a storm which would otherwise lead to irreparable damage. If your energiser is installed inside a building, then lightning protection is required.

The lightning protection mechanism is installed between the energiser and the conducting fence material. First mount the lightning protection mechanism onto a non-flammable surface near to your energiser (e.g. on a wall of the house). Next, connect it to the energiser's fence connection using a high voltage insulated lead out cable (Item no. 32615). The other part of your lightning protection mechanism is connected to the polywire using a high voltage insulated fence supply cable. For the grounding connection you should ideally use a galvanised steal core lead out cable (Item no. 32601). Use this cable to connect the lightning protection mechanism to the grounding stake.

It is a legal requirement that any electric fence systems placed near to public roads and pathways are clearly indicated with warning signs. Attach clearly visible warning signs carrying the phrase "Caution Electric Fence". (Warning sign Item no. 44735) (Different warning regulations may apply depending on your state. Find out what regulations apply in your area before installing your fence.)

Overview of electric fence components for simple polywire otter fences:

Energiser

1. 230 V Energiser NV 1100" (Item no. 42100)
2. 230 V Energiser "Extra Power 230 V" (Item no. 42110)
3. 12 V Battery energiser "Green Energy" (Item no. 44186)
4. 12 V Battery energiser "AV 6500" (Item no. 42060)
5. 9V Battery energiser BV3900 (Item no. 42030, 42031)

Fence posts

1. Metal garden posts (Item no. 45606.10)
2. Plastic posts (Item no. 44452)
3. Permanent fence post "Allround Metal Post" (Item no. 44386)
4. Fixed wooden post "Octo-Wood" (Item no. 44825)

Insulators

1. Movable insulators for garden posts (Item no. 45607)
2. Insulators with metric screw threads for "Allround Metal Post" (Item no. 44327)
3. Corner insulator with wooden thread (Item no. 44812)

44812)

1. Polywire (Item no. 42405, 44645, 44509)

Grounding

1. Grounding stake (Item no. 44219, 44307, 44375)
2. High-voltage galvanised steel core lead out cable (Item no. 32601)

Wiring

1. Polywire connector (Item no. 44684, 44751)
2. Lead out cable (Item no. 44300)
3. Fence connector cable (Item no. 44307)
4. Connecting cable (Item no. 44185, 44653)

Fence testers

1. Fence tester with digital display (Item no. 44863)

Lightning protection

1. Lightning protection equipment (Item no. 44755)
2. Fence supply cable (Item no. 32615).

Warning sign

1. Warning sign "CAUTION ELECTRIC FENCE" (Item no. 44735)

Miscellaneous

1. 12 V wet battery (Item no. 34461)
2. 9 V / 130 Ah electric fence battery (Item no. 34420)
3. Solar panel (Item no. 44412, 44465)
4. Ground fault circuit breaker (Item no. 48015)
5. Decoupling resistor (Item no. 44781).

Combination of permanent fences and electric fences

Combining a permanent fence with an electric fence usually means one made of panels or wire mesh which are then fitted with conducting material to improve their deterrent ability. To successfully keep otters away, the mesh wire thickness should be at least 2-3 mm.

To provide an optimal deterrent, the permanent fence should be around 70 cm high and have additional electric wires on the top and close to the ground.

Effect:

Otters are able to climb over or burrow under normal panel or wire mesh fences, unless it is embedded around 30 cm below ground. In practice, an electric wire running along the top of the approx. 70 cm high permanent fence will be an effective deterrent. Covering a fence with electric wire ensures that otters will no longer have any chance of climbing over without receiving a painful electric shock. Electric-fence.co.uk recommends that you run an additional electric wire close to the ground for maximum deterrent ability. This is particularly worthwhile if the fence is not embedded very deep into the ground and otters would be able to burrow under.

Please note:
Only permanent fences whose mesh is sufficiently tight to prevent otters slipping through are suitable. Gaps in the mesh should not be larger than 4 x 4 cm and for a panel fence not more than 5 x 25 cm.

Pros and cons:

Where there is already a permanent fence present, it is relatively simple, cheap and safe to equip this as an electric fence. It's robust design ensures the fence will withstand the weather for several years and requires only minimal maintenance. If an additional row of wire is needed close to the ground then this will increase the maintenance requirement slightly as this row must be kept free of any disturbances like grass or bushes. If no permanent fence is present, then building a combination fence like this will require more time and money than using a simple polywire electric fence. Furthermore, the landscape may not lend itself to building a permanent fence. Depending on your location, additional permits may be required to put up any permanent fence. You should check the rules for your area before starting any work.

Assembly:

For an optimum deterrent effect of an electric fence, electric-fence.co.uk recommends using a permanent fence combined with electric wires running across the upper and lower parts. Before you start putting up your fence, consider exactly how the fence is to be constructed and which accessories you will need. Is the permanent fence is already in place or does it first need to be built? It is much simpler if the permanent fence is already there. Then you only need to think about which accessories you will need for the electric fence. The basic equipment needed for this type of electric fence are: energiser, insulators, fence and earth connection cables, conducting material, warning sign, grounding stakes and lead out cables.

Get all materials ready and start by first positioning the electric fence insulators. Attach the insulators at both heights where the conducting material will later run. Choose a height that is close to ground, approx. 20 cm, and another towards the top of the permanent fence so as prevent climbing. If your permanent fence is a wire mesh fence with wooden posts, then you will need to use ring insulators with wood thread (Item no. 44322). These can be easily screwed into the posts and are very robust.

The top part of the permanent fence needs to be equipped with at least two conducting positive and negative rows so that a current can flow through the otter without a ground connection.

Explanation of the positive / negative principle:

The positive / negative principle is used to get around the problem that a normal electric fence system only works when a good earth connection is available (topsoil, moist ground, etc.) The impulse flows through the animal to the ground and then through the ground back to the energiser. Poorly conducting fence bases, e.g. wood, stone or plastics, prevent an effective shock being generated as these act as insulators between the conductor and the ground and so no electricity can flow. This problem also arises when installing electric fence onto pre-existing mesh wire fences (with the exception of galvanised meshes) and panel fences that are frequently used as an otter deterrent.

We can, however, get around this problem by placing several parallel wires according to the positive / negative principle. These wires are separated by a distance that is too small for the animal to slip between them without touching both. The wires are alternately connected to the ground and the fence energiser. When two wires are touched at the same time, the shock can flow unhindered from the fence wire (positive) through the animal and into the ground wire (negative). This type of design provides a very good deterrent effect.

Positive / negative principle with the 7 wire insulators.

Place the ring insulators with wood thread (Item no. 44322) 4 cm apart so that otters are unable to slip through without touching both wires. It's even easier to secure the upper part of the fence using our special 7 wire insulators (Item no. 44331, 44332). These special insulators provides guides for 7 parallel wires that are 3 cm apart and allow the positive / negative principle to be easily implemented. Use the 7 wire start / end insulators at the beginning and end of the fence respectively (Item no. 44331). This insulator has staggered holding fixtures that ensure the wires at the start and end of the fence do not touch, which would otherwise cause a short circuit. 7 wire line insulators should be used (Item no. 44332) to ensure sufficient stability on the fence. (Image 1)

(Image 1)(Image 2)

Are you looking to mount an electric fence onto an existing wire mesh or panel fence with metal post or tubes? You will need the ring insulators with metric threads (Item no. 44327). The insulators can be attached either horizontally (in front of the fence) or vertically (above the fence). If mounting horizontally, screw the insulators to the metal posts or tubes using either a tube and post mount (Item no. 44335) or two universal base plates (Item no. 46151).

Also bear in mind that the wires need to be run to the positive / negative principle at the end of the fence. For this you can have either 2 rows of ring insulators with metric threads (item no. 44327) mounted 4 cm apart horizontally on the permanent fence (image 2) or use our special 6 wire insulators (Item no. 44927 and 44928).

Our 6 wire insulators are also suitable for vertical mounting on the upper edge of the fence (Item no. 44927 and 44928). As with the 7 wire insulator, you should use 6 wire insulators at the beginning and end of the fence (Item no. 44927) with 6 wire line insulators between them (Item no. 44928). These special insulators provide guides for 6 parallel wires that are 3 cm apart and can be easily mounted to metal tubes and posts using our universal mount (Item no. 46150) with base plate (Item no. 46151).

Polywire is a particularly suitable conducting material, providing very high conductance thanks to the use of high-quality stainless steel and copper. (Item no.: 42405, 44645, 44509) Feed the wire through the insulators and mount these at the start and end of the fence. To prevent any loss of current, do not put any knots in your conducting material. Instead, use connectors (e.g. Item no. 44684, 44751) to hold the wire in place. Connectors will make it easier to re-tension the fence at a later time and also protect the conducting material.

As with any electric fence, this combination type of fence needs a good grounding connection. For this reason, a good grounding stake should be used to provide a route for the electricity back to the energiser (Item no. 44219, 44307, 44375) If the ground conditions are particularly poor, e.g. sandy, dry soil, it may be necessary to use several grounding posts. Connect these together using a highly conductive corrosion-resistant wire (ideally galvanised steel wire or lead out cable e.g. Item no. 32601).

Otters are very cautious and will first touch the electric fence with their nose and paws. These parts of their bodies are very sensitive and so an 3000 V energiser is sufficient for deterring them.

Electric-fence.co.uk recommends the use of a 230 V mains energiser. The 230 V Energiser "NV 1100" (Item no. 42100) has the necessary power and is therefore perfectly suited for defence against otters. The "NV 1100" is very easy to use and is therefore a great choice for those new to electric fences. If it's a very large pond that you need to protect, then we recommend the slightly more powerful "Extra Power 230 V" (Item no. 42110). The "Extra Power 230 V" is mains powered and reliably and safely provides the required voltage even along lengthy sections of fence and where there is light vegetation.

Insurers recommend installing a ground fault circuit breaker (item no. 48015) when using mains energisers in the home, yard or garden. This is placed between the energiser and plug socket. The energiser is instantly turned off the moment any fault currents are detected. Fault currents may be caused by defective cable insulators or moisture damage. Using a ground fault circuit breaker will avoid any accidents involving electricity.

The 12 V Battery energiser "Green Energy" (Item no. 44186) is the energiser of choice for when no mains supply is available. It is fitted with modern battery saving technology and automatically adapts itself to condition of your fence. As well as being battery powered, this energiser also has connections for mains and solar power supplies - making it extremely flexible. For longer fences or areas with a lot of vegetation, we recommend the "AV 6500" battery energiser (Item no. 42060). The "AV 6500" is very powerful, can be easily attached using the crocodile clips and comes with an indicator light so that you can quickly see that the fence is in working order.

For short fences, we recommend the 9 V battery energiser "BV 3900" (Item no. 42030, 42031).

Available power supplies for battery powered energisers are either the 12 V wet battery (Item no. 34461), which is the same as a car battery, or a solar panel (Item no. 44412, 44465). This allows you to operate your energiser economically in an environmentally safe and low-maintenance manner. For the 9 V energiser we recommend the 9 V / 130 Ah dry battery (Item no. 34420).

To ensure clean conductive connections in your electric fence use a lead out and fence connector cable (Item no. 44300 and 44407) as well as polywire connectors (item no. 44619). (Lead out and fence connector cables are included with the "AV6500").

Using a fence tester you can quickly and reliably determine how well your fence system is working. Digital testers are especially convenient, allowing you read the fence voltage from the screen at a glance. (Item no. 44863). To ensure an effective deterrent, the operating voltage should be at least 3,000 V.

For safety purposes, lightning protection equipment should also be installed. (Item no. 44755) This will prevent lightning strikes from affecting your energiser during a storm which would otherwise lead to irreparable damage. If your energiser is installed inside a building, then lightning protection is required.

The lightning protection mechanism is installed between the energiser and the conducting fence material.

First mount the lightning protection mechanism onto a non-flammable surface near to your energiser (e.g. on a wall of the house). Next, connect it to the energiser's fence connection using a high voltage insulated fence supply cable (Item no. 32615). The other part of your lightning protection mechanism is connected to the polywire using a high voltage insulated fence supply cable. For the grounding connection you should ideally use a galvanised steal core lead out cable (Item no. 32601). Use this cable to connect the lightning protection mechanism to the grounding stake.

It is a legal requirement that any electric fence systems placed near to public roads and pathways are clearly indicated with warning signs. Attach clearly visible warning signs carrying the phrase "Caution Electric Fence". (Warning sign Item no. 44735) (Different warning regulations may apply depending on your state for marking electric fence systems. Find out what regulations apply in your area before installing your fence.)

Overview of electric fence components for a combination of permanent and electric fences as otter defence:

Energiser

1. 230 V Energiser NV 1100" (Item no. 42100)
2. 230 V Energiser "Extra Power 230 V" (Item no. 42110)
3. 12 V Battery energiser "Green Energy" (Item no. 44186)
4. 12 V Battery energiser "AV 6500" (Item no. 42060)
5. 9 V Battery energiser BV3900 (Item no. 42030, 42031)

Insulators

1. Ring insulators with wooden thread (Item no. 44322)
2. 7-wire insulators with wooden thread (Item no. 44331 and 44332)
3. Ring insulators with metric thread (Item no. 44327)
4. 6-wire insulators with metric thread (Item no. 44927 and 44928)
5. Tube and post fastenings (Item no. 44335)
6. Universal mount (Item no. 46150).
7. Base plate for universal mount (Item no. 46151).

Conducting material

1. Polywire (Item no. 42405, 44645, 44509)

Grounding

1. Grounding stake (Item no. 44219, 44307, 44375)
2. High-voltage galvanised steel core lead out cable (Item no. 32601)

Wiring

1. Polywire connector (Item no. 44684, 44751)
2. Lead out cable (Item no. 44300)
3. Fence connector cable (Item no. 44307)

Fence testers

1. Fence tester with digital display (Item no. 44863)

Lightning protection

1. Lightning protection equipment (Item no. 44755)
2. Fence supply cable (Item no. 32615).

Warning sign

1. Warning sign "CAUTION ELECTRIC FENCE" (Item no. 44735)

Miscellaneous

1. 12 V wet battery (Item no. 34461)
2. 9 V / 130 Ah electric fence battery (Item no. 34420)
3. Solar panel (Item no. 44412, 44465)
4. Ground fault circuit breaker (Item no. 48015)

Electric net fence

An electric net fence is an electric fence where the conducting wire is woven into a coloured plastic mesh webbing.

Effect

The conducting mesh netting of an electric net fence provides both a mechanical and physical barrier and will very reliably keep otters and other animals away. The net fence should be at least 65 cm tall for an optimum deterrent effect. It should have conducting meshes set particularly close to the ground with a mesh size of no more than 10 x 10 cm.

Pros and cons:

Electric net fencing is very simple to put up and take down and is good value for money. The only maintenance required is to ensure it is free from any overgrown vegetation. This can be achieved by simply moving the fence slightly. Extreme weather conditions such as snow or flooding can reduce the effectiveness of an electric net fence. This problem can be tackled, however, with the use of decoupling resistors. A net fence protects you from otters by acting as a mechanical and physical barrier. There are, however, several disadvantages associated with using an electric net fence with a tight conducting mesh near to the ground: it's not only otters that are kept away from the pond, but also other animals such as hedgehogs and amphibians! They can get caught in the tight conducting mesh and die.

It is for this reason that electric-fence.co.uk recommends turning off the bottom current carrying rows, or to only use electric net fencing in areas that are free from roaming amphibians and other small animals!

Conclusion:

Ponds can be reliably protected from otters by using electric net fencing. However, such a fence poses a danger to roaming amphibians and other small animals and should therefore only be used to a limited extent in certain areas.

Assembly:

Putting up electric net fencing is very simple. Despite this, you should carefully consider the area your net fence is to cover and which accessories you will need when building your fence. As well as the electric netting, the usual electric fence materials are required: energiser, fence and ground connecting cables, warning sign and the grounding accessories.

The electric netting is of course central to the system. When building an electric net fence for the purpose of keeping away otters, netting with an extra small mesh size (Item no. 27229 and 27223) should be used to prevent otters from slipping through. The Green-Line range of small animal electric netting is a particularly good option (Item no. 27229). This 65 cm tall electric netting offers the best protection against otters thanks to its high-quality construction and very tight mesh. The inconspicuous green colour allows it to be installed around your pond without looking out of place.