18.104.22.168 states that additional protection by RCDs with a maximum rated
residual current of 30mA shall be provided for the final subcircuits
(a) one or more socket-outlets; and
(b) lighting points; and
(c) directly connected hand-held electrical equipment.
This means that any powerpoint installed up to 20A, single phase or
three phase, or any new
lighting circuit must be protected by a RCD no matter what type of
installation eg. domestic, commercial or industrial.