South African energy market

In South Africa a number of technical methods are being tested or employed by Aberdare Cables in an attempt to deter cable thieves; these could be deployed in other regions.

This article first appeared in The African Power & Energy Elites, 2019. You can read the full digital magazine here, or subscribe here to receive a print copy.

Some of these methods include the following:

Traceability

This involves marking the cable at one or more levels (on the sheath, internally or inside the conductor), and so linking the cable and/or the
conductors to the owner. Successful prosecution becomes possible when ownership of a cable or its components can be established.

The method most commonly used in South Africa for cable marking is to insert a sequentially marked tape into the cable, which is supported by databases maintained by the manufacturer. A SABS 1741 standard covering unique marking systems was published in 2018.

Physical fixing

This method secures the cable in position, making it harder for the cable to be removed. For example, cable clamps can be used which hold the cable in position on a cable rack but, while this will delay the theft process, it will not prevent it. Buried cables can also be secured by devices that prevent the cable from being pulled out of the ground using a vehicle.

Various solutions are available, among them the CableGuard system offered by Aberdare Cables.

Alternative conductor metals

The following conductor types have been considered or applied as a solution to the problem: Aluminium (hard drawn 1350): Proven to be quite effective in some applications, but limited to a minimum size of 16 mm2 due to creep related problems. Some utilities such as Eskom and City Power have moved to aluminium from copper in recent years and have tried to minimise the use of copper for electric cables.

There is however some reluctance from users to using aluminium due to corrosion problems experienced with terminations and conductors in some applications. Tinned copper and galvanised steel mix of metals: This option had found application in earth conductors and in the SaferdacTM service connection cable (alternative to Airdac). Earthing applications using a mix of these metals have been found to be problematic due to corrosion in direct buried earthing systems such as in substations, but overhead service cable applications are generally not prone to bi-metallic corrosion.

An amendment has been drafted to the SANS 1507-6 standard for service connection cables which is likely to be published during the first half of 2019.
Copper-clad aluminium (CCA): The process of applying copper tape under pressure and high temperature over aluminium rod results in a wire product where the copper and aluminium are metallurgically bonded. The NRS 110 (National Rationalised Standards) committee is currently in the process of drafting a standard for power cables with CCA conductors for use in low voltage cable applications.

Copper-clad steel (CCS): A composite conductor metal, such as copper-clad steel, which is manufactured in a similar process to CCA, or electroplated steel may be employed in earthing applications in order to drastically reduce the value of the scrap metal, as the copper is bonded to a steel substrate and cannot be easily separated. Such earthing systems have started to find application in outdoor applications in substations and earth mats and the NRS102 standard was compiled some years ago to set the requirements and application for these conductor types.

Steel: Steel has generally not found application as an electrical conductor in power cables due to its low conductivity relative to copper (10%). Low power applications such as LED lights may warrant further consideration; however, in cases where CCS is applied, these may not be suitable.

Aluminium alloy: This metal may provide a solution for small cable sizes below 16 mm2 in cases where the higher cost of CCA rules it out as an alternative to copper.

CABLE AND CONDUCTOR IDENTIFICATION

Special anti-theft cables need to be visibly distinguishable from standard cables so that thieves will recognise the cable type and refrain from cutting and damaging it before realising that it is of little scrap value. Features of antitheft cables include: non-standard sheath colours and striping of the sheath or conductors that are discoloured.