Paragraph 8 Text as text:
8 Special installations
8.1 Temporary scaffolding and similar metallic structures
8.1.1 Metallic structures assembled by means of bolted joints or screw clamps
NOTE 1 Where structures are assembled using bolted joints or screw clamps a multiplicity of such connections is likely to provide several paths of relatively low resistance. Although such structures are not designed to be electrically continuous it is reasonable to assume that they have a low value of electrical resistance.
Whatever type of structural fastenings or footings in contact with the ground are employed and however a temporary structure may be fastened to a permanent structure, it should not be assumed that a temporary metallic structure is effectively earthed.
NOTE 2 Most erections of metallic scaffolding are the subject of statutory regulations concerning construction work.
The distribution of electricity on construction sites should conform to BS7375. Except where it is necessary for lightning protection purposes (see 8.2), scaffolding external to a structure should not be connected to the means of earthing within the structure that is afforded by supply authorities.
Where scaffolding is erected against or around a structure which does not have electrical services, and electrical equipment is not likely to be used for construction work, electrical bonding for shock protection purposes may be omitted.
Where protective conductors are required, they should be of copper and protected against corrosion by a covering at least equivalent to the insulation of a single non-sheathed cable, and should be routed to avoid damage from work equipment and work activities. A conductor should be connected to scaffolding by a corrosion-resistant clamp conforming to BS951, and which is suitably protected against mechanical damage. For extensive scaffolding structures, where earthed, connections should be made at points not more than 20 m apart laterally.
8.1.2 Structures forming part of precautions to avoid danger from live overhead electric lines
COMMENTARY ON 8.1.2
The Health and Safety Executive publishes guidance on the dangers of live overhead powerlines, see Guidance Note GS6 Avoidance of Danger from Overhead Electrical Lines[5].
Paragraph 20 b) of GS6 refers to the use of a tensioned wire fence as a high level barrier, and notes that the electricity distributor has to be consulted about the erection and earthing of the barrier.
8.2 Lightning protection
If scaffolding is associated with an existing structure which has an external lightning protection system (LPS), it should be bonded to the earth termination network and the air termination network of the LPS. Lightning protection should otherwise be provided where indicated by risk assessment performed in accordance with BSEN62305