S.L. 545.24 ст. 21Protective devices to be provided at thesupplypointfor installations exceeding60Amps per phase.

(1) Three phase installations exceeding 60 Amps per phase shall be provided with a four pole switch fuse or a four pole circuit breaker as the intake of the electricity supply service.

(2) The supply intake shall be adequately protected at least by:

(a) an over current device;

(b) an earth fault protection device.

(3) Fuses and circuit breaker devices shall be graded to provide over current discrimination with the fuses provided by the electricity supply service.

(4) The main switch fuse or circuit breaker shall be mechanically linked so as to effect simultaneous disconnection of all live conductor phases and neutral.

(5) Over voltage protective device or devices that detect and protect against sustained overvoltage may be installed on downstream sub-circuits.

(6) Residual current device or devices of the appropriate type, taking into account the presence of any direct current leakage components and their magnitude, with a tripping current of 30mA shall be installed on downstream sub-circuits supplying electrical loads accessible to users:

Provided that where in the opinion of the authorised provider the unintended interruption of supply gives rise to greater risks, such as the de-energising of life support and emergency equipment, alternative arrangements for the sub-circuit supplying such equipment may be made by the authorised provider: Provided further that in the case of circuit- specific loads with high earth leakage currents, such as in the case of circuits supplying electronic equipment, which may cause unintended interruptions of supply, a residual current protection device of the appropriate type, taking into account the presence of any direct current leakage components and their magnitude and if necessary with a tripping current higher than 30mA, as recommended by the manufacturer, may be used to protect that specific load only:

Provided further that cables supplying specific loads protected by a residual current device, of the appropriate type, taking into account the presence of any direct current leakage components and their magnitude, with a tripping current exceeding 30mA shall be laid in protective conduit or trunking that provides appropriate mechanical protection. A metallic armoured cable may also be used as an alternative to the aforementioned arrangement:

Provided further that the authorised provider shall ensure that an appropriate warning sign is provided indicating that the equipment is protected with a residual current device with a tripping current higher than 30mA.