Strainer post installation

Extract from Fencing The Proven Way - Wiremark® (Brand of Pacific Steel Group).

Strainer posts mark the beginning and end of the fence and are considered the most important posts in the fence line. They carry the strain of the fence and support any gates if necessary.

Step 1 - Ground preparation

Before the hole for the strainer is prepared, attention must be given to the surrounding ground contour, as this will determine the strainer position.

Strainers should be good quality and as straight as possible. As a general rule of thumb, the strainer length should be double the fence height. Strainers that are 200mm SED (small end diameter) by 2.4m long would suit most fences.

Strainers on flat ground should stand vertical and on sloping ground 90º to the contour of the land. Angle and line posts should be placed in the same manner, so they bisect the angle of the wires perfectly and ensure the spacing of the wires remains consistent.

During construction, it is best to lay the strainer back slightly against the strain; this will allow for forward movement after tensioning.

When the hole is prepared, check for correct depth - it should be approximately half of the strainer length. Once the post has been dropped in, check for correct height and ensure it is standing against the stay side of the hole.

Step 2 - Footing the strainer

Strainer posts need to be firmly footed in the ground, to ensure that they do not lift or rotate.

Foot size can vary depending on the type of ground. Usually the softer the ground, the bigger the foot. In firm ground two foots 380mm long x 100mm wide should be sufficient. Wire used for footing should be 4mm heavily galvanised steel or 3.15mm stainless steel wire.

Two foots should be placed on either side of the strainer at the bottom of the hole. A block of timber should then be laid across the back of both foots, as this will add extra strength and prevent upwards movement.

Construction of the foot: The foot consists of a piece of ground treated timber with a 4mm or 3.15mm heavily galvanised stainless steel wire stapled in the middle, on the underside of the foot.

• The wire should be at right angles to the foot and well stapled.
• Bend the wire around the foot and neatly wrap the short end around the long wire using a pair of pliers. The tails should be left long to avoid unravelling.
• Straighten the long wire by running it through your hands, counter to the natural coil/curve of the wire, while you stand on the foot.

Step 3 - Installing the foot and ramming

1. Place one foot beside the strainer so that it finishes flat against the bottom of the hole. Follow with the second foot on the other side.
2. Check that the foot wires spiral half a turn around the strainer in the direction of anticipated movement, as this will avoid rotating and lifting - i.e., if the line wires of the fence leave the right side of the strainer, the left foot wire should be fixed on the right side of the strainer.
3. Staple any wires clear off the ground to avoid corrosion.
4. Place a block of timber across the top of both foots at the back of the strainer. This will tension the foot wires, increasing holding power and preventing backward movement.
5. Using one staple, staple the foot wires to the post approximately 150-200mm abovethe ground to ensure that the staples don’t come into contact with the soil. The staple should be 45° across the wire and driven in firmly so that the wire has to be drawn through it under tension.
6. Check the foot to ensure that it is securely in place.
7. With the foot in place, ramming can now begin. Use four separate fillings as it is important that the soil around the foot is well compacted. While ramming, constantly check that the strainer is in the desired position (flat against the front of the hole).
8. When ramming is complete, the desired wire gauge can be marked on the strainer. This should be done on both sides and will help ensure accurate and neat positioning of wires when tying off.

It is recommended that a stay is used to support the strainer post against the strain of the wires. In next month's issue we follow-up with a guide on how to trim, fit and position a stay.

Full instructions for overall construction and assembly of strainer post and stays are available on www. nzwired.co.nz/fencingtheprovenway.