Owlstone Croft, Cambridge

• Designed six individual Class IV systems to BS EN IEC 62305 and the project specification. Each block and terrace got its own air termination network, down conductors and earth termination system, so no building relies on another for its path to ground.
• Continuity tested the metallic mansards before accepting them as the perimeter conductor. Where the mansard proved sound it was used as a natural air termination; the roof plant, heat pumps, MVHR units, ductwork and structural metalwork on Block B were bonded in, with tape carried across the plant room roof.
• Bonded the structure at each down conductor position and installed each building's earth termination system with test clamps.
• Under a separate instruction, designed and installed the earthing for the site's UKPN substation to the UKPS earthing drawing: 40 x 6 mm aluminium marshalling bar 300 mm above finished floor level, copper bonded rods driven in 1.2 m sections to 4.8 m, 70 mm squared green and yellow rod and mesh connections, and BS 7430 testing with a standalone certificate to UKPS before the equipment went in.
• Issued test and commissioning certification, as fitted drawings and O&M manuals for each structure. Surge protection was excluded and written to the electrical contractor under BS EN 62305-4.

Six independent systems delivered under a JCT sub contract order valued at £18,900 excluding VAT (Blocks A and B £9,700, Terraces 1 to 4 £9,200), with a 12 month defects period. The client has given a written project reference.