Prestressed concrete poles, manufactured by INFRASET Infrastructure Projects, are being installed to carry three-phase cabling for the electrification of over 5,100 informal settlement houses at Winnie Mandela Park in Tembisa.
The electrical reticulation of Winnie Mandela Park is being undertaken by electrical contractor, Mandlakazi Electrical Technologies (MET), on behalf of the Municipal Infrastructure Department of the Ekhurhuleni Municipality. The project has been divided into five sections for implementation purposes, sections one and five having already been completed.
Section one, which entailed providing the infrastructure for medium voltage supply from the Clayville substation in Olifantsfontein to 18 mini-substations in Winnie Mandela Park, has begun in November 2007 and completed in June last year. Section five, which involved supplying approximately 800 houses with 220V electricity has begun in July last year and completed in March this year.
Four hundred prestressed concrete poles were supplied by INFRASET for section five and an order has been placed by the MET for a further 1,000 poles to be used on sections two, three and four.
Two types of poles are being used on the project, a 9m 7kN unit for intermediate loading and a 9.3m 17.5kN straining pole for end loading. The poles carry bundle conductor cables and prepaid metres which supply power to individual houses. Electric lights are being attached to every second pole.
The poles are being planted at a rate of up to ten a day and foundation shafts 1.5m deep are sunk by an earth drilling device attached to a TLB (tractor loader backhoe). Poles are planted immediately after the foundation shafts have been sunk to prevent passers-by, especially young children, from falling into the holes.
The entire project is due for completion by the end of the year when sections two to four will have been completed and MET has enlisted the support of four local BEE sub-contractors to assist with the installation process.
INFRASET railway products manager, Sizwe Mkhize, says that concrete poles were specified by the Ekurhuleni Metropolitan Municipality because their high strength-to-weight ratio and durability places them in a class of their own.
“The resilience of prestressed concrete poles enables them to recover from the effects of a greater degree of overload than any other type of pole structural material. And experience worldwide has demonstrated that during their lifetime, prestressed concrete poles are maintenance-free – a major advantage. Unlike other materials, concrete suffers no loss of strength over the years, being resistant to insects, fire, rot and corrosion.
“Our poles have an attractive rectangular tapered I-section design and are cast in high-strength, high-density concrete with a smooth finish. They are functional yet relatively light, and this makes them convenient for contractors to handle,” says Mkhize.
INFRASET poles are manufactured at ISO 9002 accredited factories in a wide range of strengths and sizes to fill most requirements in MV and LV lines. They also comply with Eskom DTC 0106 and various SABS and Spoornet specifications.