Down conductors shall be 25mm x 3mm bare annealed copper tapes installed around the outside walls of the structure. No down conductors shall be routed inside the service ducts. The down conductor shall be installed in such a way that its path is as direct as possible between air termination network and earth termination. It shall be as straight as possible along the shortest path without sharp bends or upward sections. They shall be securely fixed at intervals not exceeding 500mm by means of Naval Brass fixings with base phosphor bronze screws. The bend radii shall not be less than 200mm. Deep re-entrant loops, routing round parapet or cornices shall be avoided. However, a maximum height increase of 400mm is permissible for passing over a parapet wall with a slope of 450 or less. All wall or other building penetrations shall be made in a manner to
prevent the ingress of water/water moisture and PVC sleeves shall be provided. Unless otherwise as shown in the Drawings and/or Bills of Quantities, the number of down conductors is one for each 20 metres or part thereof the perimeter at roof level or ground level, whichever is the greater. Structures over 20 metres high shall have one per 10 metre or part thereof. Where more than one down conductor is used, the down conductors shall be arranged evenly and distributed around the outside walls of the structure. All exposed down conductors shall be painted with the decorative colour paint of the same colour for the wall finishes.