Construction World May 2015

PROJECTS AND CONTRACTS

Solving Project Lumen’s LIGHTNING STRIKE problems

“Project Lumen had specific requirements in terms of lightning protection,” says Trevor Manas, Pontins’ MD. “Besides the signif- designed and developed by Pontins’ German partners, DEHN, in conjunction with Pontins’ engineers. > icant height and size of the structure, it is situated in an area of very high lightning density – approximately 12 strikes/km 2 /year – and since being switched on in November 2013 it has suffered damage from numerous direct strikes.” Pontins is the only specialist LPS company in South Africa with access to and expertise in DEHN’s renowned HVI® Conduc- tors, and was the obvious choice to solve this intricate problem. Manas says that the previous ‘Cross Bonded’ system failed on Project Lumen because this conventional technology did not maintain a separation distance between the lightning protection conductors and the LED panels or the electrical/data supply cables of the panels. Before installing the HVI® Conductor to SANS/IEC 62305 standards, Pontins under- took risk assessments and calculated the required separation distance. The risk assessments determined that the highest lightning protection level (LPL) – level one – was required for Project Lumen. Separa- tion distance – determined utilising DEHN Toolbox software – is the minimum distance between the protection device and electri- cally conductive materials to prevent flash- over and sparking, and to ensure that the lightning currents are reliably conducted to the earth-termination system. Leading lightning protection systems (LPS) provider, Pontins, has installed a unique protection system for ABSA Bank’s Project Lumen – the world’s largest Light Emitting Display (LED) – in the Johannesburg CBD. The system comprises, inter alia, an insulated, high-voltage resistant HVI® conductor,

of protection to cover the LED’s steelwork frames,” Manas says. “We also designed the earthing, equipotential bonding, current-di- vision, layout and specialised mast brackets, which we specifically manufactured, in order to attach the masts to the I-beams,” he says. Additional surge-protection devices completed the LPS. At that height, dealing with the instal- lation challenges and safety concerns was no mean feat. Nonetheless, the installation was accelerated and accomplished within three weeks. This was possible because of the DEHN designed accessories, fittings, and installation tools used for the task. Since this showcase project was completed in December 2014, no damage of the LED system has been reported. Pontins is able to monitor the LPS through ABSA’s CCTV system and Manas says that Pontins will share footage of Light- ning striking the HVI® LPS as and when it becomes available. Pontins, wholly owned by ELB’s B&W Instrumentation and Electrical, provides earthing, LPS and surge protection that is easily installed, economical, aesthet- ically appealing, and appropriate to the widest possible range of industrial and resi- dential purposes.

The ABSA Towers building was constructed using steel-reinforced concrete. Electric continuity tests performed on the concrete steel reinforcing at strategically exposed points established that the interconnected reinforcing should be used as natural down conductors, and natural earth electrodes, to enhance the division (splitting) of the light- ning’s current in the event of a direct strike. “Basically, a conductor must have suffi- cient current-carrying capacity, be insu- lated to the sufficient electrical strength and prevent creeping discharge or flashover and the particular HVI® Conductor that we installed fits the bill perfectly,” says Manas. “The HVI® conductor is unique. This coaxial conductor has an inner copper core wrapped in thick-walled high-voltage-re- sistant insulation that is encased within a special semi-conductive weather-resistant sheath,” Manas says. For this installation, two three-metre masts were installed, with two HVI® Power Conductors (LPL 1) carrying the current down from each mast to the rebar. “Once we’d established the require- ments, we designed the isolated air terminal system to intercept and prevent penetration of strikes, calculated the height and posi- tioning of these terminals and the angle

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Leading lightning protection systems provider, Pontins, has installed a unique protection system for ABSA Bank’s Project Lumen – the world’s largest LED – in the Johannesburg CBD.

CONSTRUCTION WORLD MAY 2015