IEC 60364-4-43:2001

Specifies where overload and short-circuit protective devices have to be placed in the run of the conductor. States particular requirements for protection of phase and neutral conductors according to TN, TT and IT systems. Note: -Requirements do not take account of external influences. For application of protective measures in relation to conditions of external influences, see IEC 60364-4-482.

Sets out general rules for protection of live conductors against overload and short circuit. Specifies the features of various protective devices and necessary coordination between conductors and overload protective devices. Formula for calculation of time in which a given short-circuit current will raise a conductor from the highest admissible temperature in normal duty to its limit temperature. Enumerates requirements for coordination of overload and short-circuit protection. Note: For details of -low-voltage circuit breakers, see IEC 60947-2 -low-voltage fuses, see IEC 60269 -for coordination of low-voltage direct-online (full voltage) motor starters with short-circuit protective devices, see IEC 60947-1 -for current-carrying capacities of conductors for electrical installations of buildings, see IEC 60364-5-523.

IEC 60364-4-43:2008 provides requirements for the protection of live conductors from the effects of overcurrents. IEC 60364-4-43:2008 describes how live conductors are protected by one or more devices for the automatic disconnection of the supply in the event of overload (Clause 433) and short-circuit (Clause 434) except in cases where the overcurrent is limited in accordance with Clause 436 or where the conditions described in 433.3 (omission of devices for protection against overload) or 434.3 (omission of devices for protection against short-circuit) are met. Coordination of overload protection and short-circuit protection is also covered (Clause 435). This third edition cancels and replaces the second edition, published in 2001, and constitutes a technical revision. The main changes with respect to the previous edition are: - Introduction of new informative Annexes B, C and D. - Information concerning flexible cables added to Scope. - Requirements added for overload detection for the neutral conductor for harmonic currents. - Requirement that devices for protection against short-circuit current be capable of making as well as breaking short-circuit current added. - Information added to clarify protection against overload current. - Requirements where devices for protection against overload need not be provided expanded. - Requirements where devices for protection against short-circuit need not be provided expanded. - Requirements for short-circuit current ratings of busbar trunking systems added. The contents of the corrigendum of October 2008 have been included in this copy.