Comply with the General Conditions, Supplementary Conditions and the requirements in various Sections of the Electrical Specification. In addition read and conform to all Electrical Sections of these specifications. The installation shall comprise air networks connected to roof and down conductors and finally terminated in earth electrodes, via structural re-bars and suitable test points in accordance with the details included on the attached drawings or in the Specification Section.
Provide all labour, materials, products, equipment and services to supply and install the lightning protection systems as indicated on the drawings and specified in these specifications.
Reference Standards for Lightning Protection System
Provide a lightning protection system in accordance with BS 6651 and IEC 61024 to protect the building structure and personnel from the risk of a lightning strike.
All electrical installations shall be carried out in accordance with the best International Standards and Codes of Practice specifically with the current issue of the IEE Regulations (BS 7671) and the requirements of the supply authority.
The entire installation shall be installed and tested in accordance with the relevant British and International Standards and any requirements of local authority.
Coordination for Lightning Protection System
Contractor to allow for coordination with other contractors and employing a specialist supplier to ensure that a comprehensive lightning protection installation is provided.
Whilst other Divisions are providing (by nature of their work) components of the lightning protection system, the contractor is responsible for the overall system. This includes the supervision and testing the provision of dedicated reinforcing bars and also the bonding of the building cladding system to the network of down tapes and equipotential conductors.
Responsibilities to Lightning Protection System Installation
Where necessary, engage a specialist to undertake the design, installation, testing and commissioning of the lightning protection system.
The MEP contractor shall assume responsibility for the overall system including:
- vertical and horizontal copper aluminium tape conductors as detailed in the specification and drawings.
- linking the conductor system to the structural steelwork and reinforcing bars.
- testing the whole system in conjunction with the cladding and structural package contractors.
- provision of test points and reference electrodes.
- miscellaneous bonds to structural steelwork, lift guide rails, BMU track, grilles, spire structure, glazing mullions and any other exposed metallic conductive parts.
- linking the substation earth bar network to the lightning protection system.
The Structural Contractor is responsible for providing continuous structural steelwork and reinforcement bars which are electrically continuous and also shall be responsible for the verification of the testing of joints etc to the satisfaction of the appointed specialist sub-contractor prior to concrete pours.
The piling Contractor is responsible for ensuring the pile steelwork/reinforcement is electrically continuous and shall also be responsible for the verification of the testing of joints etc during construction of the cage mesh and prior to the concrete pour.
Ensure suitable tails are provided by the contractor at the pile cap/raft slab point for future connection/extension onto the steel reinforcing of the system by the other Contractors.
The cladding Contractor is responsible for providing and connecting earth tails on to the cladding primary support structure where necessary. The other end shall be connected on to the lightning protection system conductor tapes by the other Contractor.
Shop Drawings For Lightning Protection System
Provide complete shop drawings as produced in conjunction with the appointed specialist sub-contractor.
Products for Lightning Protection System
The Contract shall include for the supply and installation of all necessary components to provide a complete lightning protective system to the Tower structure as detailed in the following Specification Sections in order that the building(s) may be protected against the effects of a lightning discharge in accordance with British Standard BS.6651.
The installation shall comprise air networks connected to roof and down conductors and finally terminated in earth electrodes, via structural re-bars and suitable test points in accordance with the details included on the attached drawings or in the following Specification Section.
Each component shall be suitable for application and as specifically detailed in the following Specification Sections and/or drawings.
Conductor tape saddles shall be fixed to the walls by Round-head 37.5mm x No. 8 brass wood screws and rawlplugs, the saddles being spaced at not less than 1.00m intervals. As an alternative the Contractor may cast pockets into the structural wall and secure studs via vast resin adhesive once the form-work is removed.
Bi-metal connections shall be provided between aluminium and copper interfaces and elsewhere as necessary to avoid electrolytic action.
Lightning Protection Roof Conductors
Air terminations shall be formed and be of the type shown on the drawings.
Provide a network of conductor tape around the roof area of the building. This shall be used to connect all down conductors, window cleaning track, cladding, spire, structural reinforcing and all other exposed conductive metal parts to a common potential.
The roof conductors shall be fixed to the roof surface by means suitable saddles, positioned at intervals not exceeding 1.00m by suitable means, care shall be taken to ensure that any holes formed in the cladding, are effectively sealed to prevent ingress of water. This shall be confirmed and agreed with the Contractor.
Lightning Protection Down Conductors
- Provide down conductor tapes in locations as indicated on the drawings.
- Down conductors shall be either: Installed surface on the structure concealed behind the cladding OR Reinforcing bars within the concrete structure.
- Down conductor tapes shall terminate on to dedicated reinforcing bars which shall be utilised as the final connection to earth via the pile foundations. The Contractor shall include for supervising and testing the installation of the reinforcing bars including all joints prior to the concrete being poured.
- Down conductors to be connected at roof level to a common loop tape.
- Provide horizontally mounted conductor tapes at levels indicated on the drawings. These shall provide a common connection for all down conductors, structure, cladding, steelwork and exposed metalwork.
Lightning Protection Test Points
Provide a joint for test purposes at approximately 1m from finished floor level in an accessible location, unless otherwise detailed, on every down conductor. The test link shall be of cast gun-metal and be proprietary manufactured to enable the electrode to be removed from the lightning protection system.
Lightning Protection Earth Reference Pits
- Certain individual down conductors shall be effectively bonded to suitable 3.60m long by 16mm diameter earth rods manufactured from hard drawn copper rod in the form of 1.20m sections. Each section shall be complete with internal screws and socket. The earth reference electrode shall be installed not more than 1.00m away from the building with the earth reference electrode head located not less than 500mm below the ground level. Final connection of the down conductor to the earth reference electrode shall be made by means of a pressure type connector clamp.
- The Contract shall include for the supply and delivery of inspection pits manufactured as detailed in the attached Specification Section and/or drawings, these to be handed over to the contractor for installation. An inspection pit shall be supplied for each earth termination. Heavy duty covers suitable to withstand vehicular traffic shall be provided for pits located in the roadway areas. The lid of each pit shall be lockable and jam free construction and supplied with the appropriate key.
- Where electrode points are located internally within building floor slabs they shall comprise a suitable earth rod water seal installed in the base of a pocket formed in the slab, with the pocket and associated cover.
- The body of each earth pit shall as a minimum comprise shatter-proof, lightweight, polymer material with a high resistance to chemical damage from such substances as petrol, oil, diesel, bitumen etc. Each unit shall include high ultra-violet stability, wide temperature application and earth bar facility (where necessary) to permit multiple earth tape connections to be made. Where these are not suitable concrete pits shall be provided.
Manufacturers of Lightning Protection Materials
Site Execution of Lightning Protection System
- All metallic projections, ducts, vent pipes, gutters, radio and television aerials, fan housings, window cleaning equipment and tracks etc, on or above the main surface of the roof structure shall be bonded to and form part of the air termination network.
- No joints in either the down conductor or roof conductors shall be allowed other than at air terminal, earth electrodes and terminal or test block positions.
- Where it is found that the resistance to earth at any test point is in excess of 10 ohms, the length and number of earth electrodes shall be increased to the instructions of the MEP Consultant, in order to comply with the requirements of the British Standard. The resistance of each metallic conducting path, including all joints, shall not exceed 6% of the calculated resistance of the copper tape itself. In addition, the resistance from the earth electrode to the nearest test clamp shall not exceed 0.2 ohms.
- The Contractor shall include ensure that at the completion of the installation to resistance to earth from each testing point does not exceed 10 ohms, the tests being carried out in accordance with BS 7430. The Contract shall include for the performance of these tests and submitting the results to the MEP Consultant.
- Connections to the earth electrodes shall not be covered over with top soil without the permission of the MEP Consultant.
- Upon completion of the works, submit a certificate of installation to the MEP Consultant for review and approval.
- The operating and Maintenance manuals shall be compete with system records to BS 6651 that includes the following items as a minimum:
- As installed drawings
- Nature of soil
- Earth resistivity measurement.
- Earth electrode resistance.
- Details of earth electrode types and locations Include a copy of the certificate in the O&M manuals.