Over 3 000 prestressed I-section concrete poles are being supplied by Aveng Manufacturing Infraset for the electrification of the integrated housing development in Fleurhof, Roodepoort, in Gauteng.
The development involves the construction of 9 600 houses, between 30m² and 100m² in size. The building programme began in 2010 and will run until 2016. Some of the units are being sold on the open market, others fall under the RDP umbrella and the balance are being allocated for social rental and the gap market.
The concrete poles are being installed by Kusokhanya Electrical Construction (KEC) using two installation teams, one for the planting of the poles and the other for stringing three-phase bundle conductors, the installation of metering boxes at the apex of the poles, and the mounting of distribution boards inside the houses.
KEC is also installing 15 mini substations. Underground cabling rated at 6.6kVA feeds the stations and the overhead bundling conductors are rated at 400V.
Bruce de Villiers, KEC’s site manager, says that the installation teams include a local-community labour component of 45%. “Many of these people were unskilled and we have trained them in all aspects of the work, including the stringing of bundle conductors and the installation of the metering boxes,” he says.
An average of 30 poles a day are being planted by KEC. The poles supplied include 7.0m, 4kN units, 7.2m, 10kN straining poles, and 7.5m, 20kN end units.
De Villiers says the I-section poles are ideal for this type of installation. “They have an excellent strength-to-weight ratio and their relatively light weight means they are easy to offload and handle. The shape of the poles also makes the mounting of the prepaid meter boxes easy and secure.”
Aveng Manufacturing Infraset poles and masts product manager, Mothemane Makhura, says that all the I-poles for the Fleurhof project were manufactured with earthing bars to protect them against lightning. “They were cast at our Brakpan factory in high-strength, high-density concrete with a smooth finish,” he adds.
The prestressed concrete poles also have the advantage of resilience, which enables them to recover from the effects of a greater degree of overload than any other type of structural material, and of being maintenance-free for life. Unlike other materials, concrete suffers no loss of strength over the long term and it is resistant to insect attack, fire, rot, and corrosion.
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