IEC 60364-4-473:1977+AMD1:1998 CSV

FOREWORD
MEASURES OF PROTECTION AGAINST OVERCURRENT
1 Measures of protection against overload
  1.1 Position of devices for overload protection
  1.2 Omission of devices for protection against overload
  1.3 Position or omission of devices for protection
      against overload in IT systems
  1.4 Cases where omission of devices for overload
      protection its recommended for safety reasons
  1.5 Overload protection of conductors in parallel
      1.5.1 Equal current sharing between conductors
      1.5.2 Unequal current sharing between conductors
2 Protection against short circuit
  2.1 Position of devices for short-circuit protection
  2.2 Alternative position of devices for short-circuit
      protection
  2.3 Omission of devices for short circuit protection
  2.4 Short-circuit protection for conductors in parallel
3 Requirements according to the nature of the circuits
  3.1 Protection of phase conductors
  3.2 Protection of the neutral conductor
      3.2.1 TT or TN systems
      3.2.2 IT systems
  3.3 Disconnection and reconnection of the neutral
      conductor
Annex A (informative) Protection of conductors in
        parallel against overcurrent
      A.1 Introduction
      A.2 Overload protection of conductors in parallel
      A.3 Short-circuit protection of conductors in parallel

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.