POLES FOR LIGHTING
ROCLA’S spun poles for street lighting are manufactured from high quality, durable reinforcement concrete, in a standard range of lengths from 4,5m to 13,0m. The elegant appearance of the pole with its smooth light grey finish which is unique, creates a uniformly smooth impervious finish. Lighting poles are made to a standard specification in SABS 470, however strengths and lengths can be designed and manufactured to suit customer requirements. Rocla’s poles are manufactured with an integral earthing system which consist of stainless steel ferrules which are flushed with the outside of the pole, enabling an electrical connection to all the poles reinforcing wire.
ROCLA manufactures electrification mast for the railways which requires a concrete pole design capable of handling very high loading. The Rocla engineering department is responsible for handling the application of the concrete poles.
For more information about Tractional Poles, visit: www.roclaproducts.co.za/prod_traction_masts.asp
POLES FOR ELECTRIFICATION
ROCLA concrete poles are designed for the electrification within townships. The concrete poles provide the following benefits such as:
- An optimized design enabling the use of standardized fittings and aids productivity of installation.
- The poles are resistant to vandalism, fire they are maintenance free and durable.
ROCLA’S concrete poles are designed for reticulation systems which supply 11kv and 22kv of power to farming communities. The poles are designed with precast holes and the strength to accommodate the customer’s conductor span lengths. The advantage of the concrete pole is it’s resistance to veld fires and it can also eliminate the cost of replacing formerly used wooden poles.
ROCLA recently developed concrete poles to aid in satisfying environmentally friendly structure of concrete poles, which caters for a pre-determined load and standardized fittings. These poles are extremely cost effective to the traditional alternatives and offer a maintenance free long life span advantage.
HANDLING AND INSTALLATION
Normal cast concrete poles should be transported with the narrow face of the pole upwards. Layers of poles must be separated by timber not less than 100 x100m in a section, which means bearers must be placed ¼ of the a pole length from each end of the concrete pole together with centre support. To even out the load distribution the pole tips and butt should be alternated. The transportation of spun concrete poles up to 12m in length, requires a trailer with a rigid loading platform and chassis. Poles exceeding 4,5m in length must be supported at a minimum of three points. The supports should be made from steel or hardwood, covered in rubber and shaped to accommodate the pole diameter.
Care must be taken when handling, transporting and storing concrete poles to avoid overstressing them or causing damage. Lack of care can be costly. When unloading poles by crane on site, a single point lift may be used, please contact your nearest Rocla office to establish the correct position of the lift point for the particular poles. To avoid point loads or abrasion damage at the lift point, a protective timber corset about 0.5m long should be used, otherwise use a thick wrapping of canvas or jute bagging under the lifting chain or even a fabric sling. When the pole is to be lifted for insertion into the ground, a one point lift must be used. The lift point must be 1/3 of a pole length of the top of the pole. For a two way lift, the lifting positions should be ¼ of a pole length form each end of the pole.
All Rocla poles carry a mark which indicates 1,5m above the design ground level in order to gauge the correct planting depth. Pole holes should be dug so that the access slope into the hole will be parallel to the feeder line. The width of the hole should be as narrow as possible, while allowing the pole to be planted to the correct depth.
A PRACTICAL WAY OF PLANTING LARGE POLES IS AS FOLLOWS:
- Use a concrete manhole ring as a sleeve. (this sleeve could be planted and backfilled)
- The pole should be chicked into position and the crane can come on the next hole, whilst the annulus between sleeve and pole could be filled with a sand/cement mix afterwars.
COMPACTING SOIL AFTER PLANTING POLES
The soil should be dampen after the pole has been planted. If the soil is squeezed in the hand and holds its shape when the4 hand is opened, this indicates the right moisture content to ensure good soil compaction. Therefore backfill the hole 300mm layers at a time. Compact each layer with a mechanical compacter or with a hand stomper of at least 25kg in weight. Drop the compacter 400mm per blow and apply 30 blows to each layer of soil around the pole.
If you encounter difficult soils the procedure must be modified:
- A loose soil, that does not compact when wet, must be thoroughly mixed with three pockets of cement for each m3 of material. Note that the pole will need at least two days before any tension can be applied.
- A very clayey, wet soil must be replaced altogether by an important soil. The imported material should preferably be a well graded silty soil. This should be mixed with cement, moistened and used as backfill according to the previous compaction procedure. For tall concrete poles, in a wet clayey area extra stabilizing will be needed. It is recommended that four concrete lintels (1,0m long x 100mm x 100mm) are used as baulks. The soil behind the lintels must be placed against the pole on the opposite side to the intended service take off. Finally the soil behind these two lintels must be thoroughly compacted.