scope:

(431)¹

Part 4-43 of IEC 60364 describes how live conductors are protected by one or more devices for automatic interruption of the supply in the event of overload (see clause 433) and short-circuits (see clause 434) except in cases where the overcurrent is limited in accordance with clause 436 or by the conditions described in 433.4, 443.5 or 443.3 are met. Further, protection against overload and against short-circuits shall be co-ordinated in accordance with clause 436.

NOTE 1 Live conductors protected against overload in accordance with clause 434 are considered to be protected also against faults likely to cause overcurrents of a magnitude similar to overload currents.

NOTE 2 The requirements of this standard do not take account of external influences. For the application of protective measures in relation to conditions of external influences, see 410.3.4 of IEC 60364-4-41 and clause 422 of IEC 60364-4-42.

NOTE 3 Protection of conductors according to this standard does not necessarily protect the equipment connected to the conductors.

(433.1 and 434.1)¹

Protective devices shall be provided to break any overcurrent flowing in the circuit conductors before such a current could cause a danger due to thermal and mechanical effects or a temperature rise detrimental to insulation, joints, terminations, or surroundings of the conductors.

¹ In this standard, references in brackets refer to the previous numbering system.