### Electricity (Wiring) Regulations 《電力(線路)規例》

8. Isolation and switching
(1) Effective means, readily accessible for operation, shall be provided so that all voltage may be cut off from every fixed installation, from each of its circuits and from all electrical equipment connected to each circuit, as may be necessary to prevent or remove danger.
(2) Where motorised drives are involved with moving parts that are readily accessible and that may cause bodily injury, there shall be an effective means of disconnection locally placed for ready operation so that all voltage may be cut off from the motorised drives.

9. Overcurrent protective devices
A circuit shall be protected against overcurrent by a device that—
(a) operates automatically to break the circuit before the safe current rating of the circuit is exceeded;
(b) is of adequate breaking capacity;
(c) is suitably located; and
(d) is properly constructed,
so as to prevent danger from overheating, arcing or the scattering of hot particles when the device comes into operation and so as to permit restoration of the supply without danger.

10. Neutral conductor protective devices, isolators and switches
(1) A single-pole switch shall be inserted in the phase conductor of a single phase circuit only.
(2) No fuse and no circuit breaker, isolator or switch, other than a linked circuit breaker, linked isolator or linked switch, shall be inserted in a neutral conductor.
(3) Notwithstanding subregulations (1) and (2), a single-pole switch may be inserted between the earthing connection and the neutral terminals of generators running or likely to be running in parallel so long as adequate precautions have been taken to avoid danger.
(4) A solid link may only be inserted in a neutral conductor so long as it cannot be disconnected without first disconnecting the related phase conductors or without using a tool. (L.N. 323 of 1990)
(5) A linked circuit breaker, a linked isolator or a linked switch inserted in a neutral conductor shall be arranged to break also the related phase conductors.

### Electricity (Wiring) Regulations 《電力(線路)規例》

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.

Editorial Note:
* Commencement date: 1 June 1992.

### Electricity (Wiring) Regulations 《電力(線路)規例》

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.

Editorial Note:
* Commencement date: 1 June 1992.

13. Conductors, joints and connections
(1) A conductor shall be of sufficient size and current-carrying capacity for its intended purpose.
(2) A live conductor shall be protected against accidental direct contact by a person.
(3) An electrical joint, connection and conductor shall be properly constructed and installed with respect to conductance, insulation, mechanical strength and protection.

14. Wiring installation enclosure
(1) An enclosure of a wiring installation shall be properly designed, constructed, installed, protected and maintained so as to prevent danger.
(2) Good workmanship and suitable materials shall be used for the enclosure of a wiring installation.

15. Adverse conditions installation
Where all or part of a fixed electrical installation is—
(a) in or likely to be in water or exposed or likely to be exposed to weather;
(b) exposed or likely to be exposed to high ambient temperature, corrosive atmosphere, polluting substances or other adverse hazardous conditions; or
(c) in surroundings susceptible to risk of fire or explosion,
it, or the relevant part of it, shall be specially constructed, installed or protected to prevent danger arising from those adverse conditions.

16. Overhead line installations
(1) A low voltage overhead line shall be designed, constructed, installed and protected so as to prevent danger.
(2) The height above ground of a low voltage overhead line at any point of the span shall not be less than 5.8 m across any place accessible to vehicular traffic and 5.2 m otherwise.
(3) No overhead line operating at high voltage shall be installed without the Director’s approval.