RCDs: protection of cables concealed in walls or partitions
Reference to ‘under the supervision of a skilled or instructed person’ has been removed from the regulations concerned.
Consequently, the requirement to provide RCD protection to cables concealed in a wall or partition will apply to all installations, except where one of the other permitted methods of protection is employed (such as the use of cables having an earthed metallic covering or cables enclosed in an earthed metal conduit). The RCD must have a rated residual operating current (IΔn) not exceeding 30 mA and an operating time not exceeding 40 ms at 5 IΔn.
As at present, the revised requirements apply to cables at a concealed depth of less than 50 mm from the surface of a wall or partition and, irrespective of depth, if the cable is in a partition constructed of metallic parts other than fixings (such as nails or screws).
There is still an exception for cables forming part of a SELV or PELV circuit.
Cables must still be installed within the ‘safe’ zones illustrated in Figure 1, except where they have one of the other permitted methods of protection mentioned above, or they form part of a SELV or PELV circuit.