Hong Kong Regulations

ELECTRICITY (WIRING) REGULATIONS - REGULATION 12

Earthing arrangement

(1) A fixed electrical installation shall have an effective earthing
arrangement, including a connection to earth electrodes, for its protection
against earth fault currents and dangerous earth leakage  currents.

(2) In addition to the requirement under subregulation (1), where the supply
is taken directly from an electricity supplier's transformer within the
premises in which the fixed electrical installation is situated, the
main earthing terminal of the installation shall be bonded to the supplier's
bonding terminal that connects to the earthed point of the transformer.

(3) In addition to the requirement under subregulation (1), where the supply
is taken from the electricity supplier's underground cable that has
exposed conductive parts at the cable termination at the point of supply, the
main earthing terminal of the fixed electrical installation shall be bonded to
those exposed conductive parts.

(4) Where bonding referred to in subregulations (2) and (3) is used to prevent
the rise of a dangerous earth potential, the fixed electrical installation
shall satisfy all the requirements of regulation 11 even if the bonding is
disconnected.

(5) Subregulations (2) to (4) apply only to a fixed electrical installation
that is completed or substantially altered on or after the commencement of
this regulation. (Enacted 1990)