Hong Kong Regulations

ELECTRICITY (WIRING) REGULATIONS - REGULATION 11

Earth leakage and earth fault currents

(1) A circuit shall be provided with effective means to prevent the
persistence of earth fault currents and dangerous earth leakage currents.

(2) Where metalwork of electrical equipment, other than its current-carrying
conductors, may become charged with electricity in a manner that would cause
danger if the insulation of a conductor becomes defective or if a fault occurs
in the equipment, the metalwork shall be earthed in a manner that will cause
safe discharge of electricity, or other effective means shall be provided to
prevent the occurrence of danger.

(3) Where metalwork is earthed in accordance with subregulation

(2), the circuits concerned shall be protected against the persistence of
earth fault current by-

   (a)  an overcurrent protective device in accordance with regulation 9; or

   (b)  a residual current device or an equally effective device, to
        automatically disconnect the faulty circuit in time to avoid danger.

(4) Where metalwork of electrical equipment is earthed in accordance with
subregulation (2) and the metalwork is accessible simultaneously to a
substantial extraneous conductive part, the extraneous  conductive part shall
be effectively connected to the main earthing  terminal of the fixed
electrical installation.

(5) Subregulation (4) applies only to-

   (a)  a fixed electrical installation that was completed on or after 1
        January 1985; and

   (b)  a fixed electrical installation that was substantially altered on or
        after 1 January 1985 or that is substantially altered after the
        commencement of this regulation. (Enacted 1990)