Thinking outside the box to supply fresh water

Glencorse Water Treatment Works is a greenfield development and will soon be on-line supplying 70 per cent of Edinburgh’s drinking water. The overall objective is to provide clearer, fresher drinking water to around half a million people in Scotland’s capital and support the continued economic growth of the city where possible.

“This is a very important project for Scottish Water. Edinburgh has a population of 500,000 and could grow by 20 per cent in the foreseeable future. Being the second most visited tourist destination in the UK, a lot of people will depend on the reliability of Glencorse,” says Garry Hall engineering manager of Field Systems Designs, the specialist electrical engineering company installing the lighting and cabling the process drives and instrumentation as well as fire and intruder alarms. “It was essential we installed only the best equipment and worked to the highest standards so that we can be sure of long-term reliability.”

Hall and his team reassessed many of the items of equipment they would normally use in light of the long life expectancy of the plant. It was clear many different sizes of junction box would be needed, yet it would be advantageous to procure them all from a single range, in order to keep costs as low as possible. To rationalise the project requirements Katherine Beddard, FSDL Project Engineer for Glencorse, classified the junction boxes by both size and configuration.

“We were also concerned with the IP rating and impact resistance as some installation points were outside and in harsh environments.”

Hensel’s DK range was identified as being wide enough to meet the needs of the job and seemed to have all the quality issues addressed. A meeting was arranged with Hensel’s distributor Cee Norm which had experience with big water industry installations.

Cee Norm’s Graham Fox recalls:

“I realised that ease of installation – and subsequent maintenance and reconfiguration – would be key considerations. It was also clear steel wire armoured glands would be used extensively on-site. FSDL’s electricians often complain of the lack of glanding space with the off-the-shelf boxes normally supplied as the spacing between glands increases resulting in a number of the cable entry knockouts being unusable. I suggested we went with the Hensel DK range and used a larger spacing for the knockouts into which the glands would be mounted.”

Dave Harding, the electrical supervisor for FSDL at Glencorse says: “The junction boxes supplied were perfect for the harsh environment they were exposed to and the terminals and terminating space inside the junction boxes made the install and future maintenance much easier.”

Cee Norm could perform the special knockout machining at its engineering base in Telford, making most of the boxes ahead of schedule but always being ready for the inevitable last minute extra call-off.

The DK cable junction boxes are to a solid, modern and user friendly design, so ticked the main boxes for Glencorse. They are halogen- and silicone-free, meeting stringent environmental specifications, while their stainless steel quick fastening screws meet installation and longevity needs. The vibration tolerant terminals were suitable for a site under continual operation. Hensel makes its DK range so that they can comply with IP54, 55 or 65 ratings. They are VDE tested and conform to the new international standard 60670-22. Critically for a large project they can take a range of cable entry options including most grommets and gland types and can be drilled or adapted on-site.

“We’ve previously used DK in really demanding applications – offshore, underground, trackside, in chemical works and power stations,” says Fox, “so are confident they can stand up to most things.”

For Hall, he says he likes the way DK combines high performance with aesthetics. “On a prestigious job like this you want to walk away from an installation that looks good as well as functionally correct. The fact that we could customise each box in terms of knockout size and position makes the end product look really professional.