Addenbrooke Extra Care, Gosport
Lightning protection to an extra care housing scheme using the metal roof as the air termination, 19 aluminium down conductors and 19 copper bonded earth rods, followed by annual testing.
- Client
- Touch
- Location
- Willis Road, Gosport, Hampshire PO12
- Sector
- Healthcare and extra care
- Year
- Annual test 2024
19
Down conductors
19 x 2.4 m
Earth rods
Pass
2024 annual test
The challenge
An extra care scheme with a standing metal roof and a large footprint. The roof metal was thick enough to act as its own air termination under Table 5 of BS EN 62305-3, which removed the need for a tape mesh on the roof, but the building's perimeter still needed a full set of down conductors and earths. On a residential care building the conductors also had to be tidy and unobtrusive on the finished elevations, and the earths had to sit in inspection chambers for safe future testing.
What we did
- Designed the system to BS EN 62305 with the metallic roof surface used as the air termination network, on the basis that it is mechanically and electrically continuous and within the thickness requirements of Table 5 of BS EN 62305-3.
- Installed 19 down conductors of 25 x 3 mm PVC sheathed aluminium tape, connected to the roof metal at high level and fixed to the finished facade with non metallic proprietary fixings, each terminating at low level on a stainless steel test point.
- Drove 19 earth electrodes of 2.4 m x 16 mm steel cored copper bonded rod, each set in an inspection chamber that doubles as the test location.
- Bonded all extraneous metallic items into the system with aluminium bonding clamps to BS 7430.
- Returned in June 2024 for the annual test and inspection of all 19 electrodes and issued a Pass certificate.
Outcome
A metal roof system with 19 down conductors and 19 rods, tested and certificated on completion. The June 2024 annual test recorded a Pass and the certificate was issued to the client, with the next test due 12 months on.
Standards
- BS EN 62305-3, Table 5 natural components
- BS EN 62561
- BS 7430
- BS EN 13601 conductors
- Protection
- Earthing
- Maintenance
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