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IEC 60364-5-53
Edition 4.0 2019-02
INTERNATIONAL
STANDARD
colour
inside
Low-voltage electrical installations –
Part 5-53: Selection and erection of electrical equipment – Devices for protection
for safety, isolation, switching, control and monitoring
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IEC 60364-5-53
Edition 4.0 2019-02
INTERNATIONAL
STANDARD
colour
inside
Low-voltage electrical installations –
Part 5-53: Selection and erection of electrical equipment – Devices for
protection for safety, isolation, switching, control and monitoring
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.01; 91.140.50 ISBN 978-2-8322-6509-3
– 2 – IEC 60364-5-53:2019 IEC 2019
CONTENTS
FOREWORD . 6
530.1 Scope . 8
530.2 Normative references . 8
530.3 Terms and definitions . 11
530.4 General and common requirements. 14
530.5 Erection of equipment . 14
531 Devices for protection against indirect contact by automatic disconnection of
supply. 14
531.1 Overcurrent protective devices . 14
531.1.1 TN systems . 14
531.1.2 TT systems . 14
531.1.3 IT systems . 15
531.2 Residual current protective devices. 15
531.2.1 General conditions of installation . 15
531.2.2 Selection of devices according to their method of application . 15
531.2.3 TN systems . 15
531.2.4 TT systems . 16
531.2.5 IT systems . 16
531.3 Insulation monitoring devices . 16
532 Devices and precautions for protection against thermal effects . 16
532.1 General . 16
532.2 Locations with a particular risk of fire . 16
532.2.1 General . 16
532.2.2 Locations with external influences BD2, BD3 or BD4 . 17
532.2.3 Locations with external influences BE2 . 17
532.3 Selection of arc fault detection devices (AFDD) . 18
533 Devices for protection against overcurrent . 18
533.1 General requirements . 18
533.1.1 General . 18
533.1.2 Compliance with standards . 18
533.1.3 Fuses . 19
533.2 Selection of devices for protection against overload current . 19
533.2.1 General . 19
533.2.2 Presence of harmonic currents . 20
533.2.3 Unequal current sharing between parallel conductors . 20
533.3 Selection of devices for protection against short-circuit current . 20
533.3.1 Thermal stresses . 20
533.3.2 Breaking capacity . 21
533.4 Positioning of overcurrent protection devices . 21
533.4.1 General . 21
533.4.2 Positioning of devices for overload protection . 21
533.4.3 Positioning of devices for short-circuit protection . 22
533.5 Co-ordination of overload and short-circuit protective functions. 23
533.5.1 Protective functions provided by one device . 23
533.5.2 Protective functions provided by separate devices . 23
534 Devices for protection against transient overvoltages . 23
534.1 General . 23
534.2 Void . 24
534.3 Void . 24
534.4 Selection and erection of SPDs . 24
534.4.1 SPD location and SPD test class . 24
534.4.2 Transient overvoltage protection requirements . 25
534.4.3 Connection types . 25
534.4.4 Selection of SPDs . 27
534.4.5 Protection of the SPD against overcurrent . 31
534.4.6 Fault protection . 33
534.4.7 SPDs installation in conjunction with RCDs. 34
534.4.8 Connections of the SPD . 34
534.4.9 Effective protective distance of SPDs . 36
534.4.10 Connecting conductors of SPDs . 37
535 Co-ordination of protective devices . 37
535.1 Selectivity between overcurrent protective devices . 37
535.1.1 General . 37
535.1.2 Partial selectivity . 38
535.1.3 Full selectivity . 38
535.1.4 Total selectivity . 38
535.1.5 Enhanced selectivity . 38
535.2 Co-ordination between residual current protective devices and OCPDs. 39
535.3 Selectivity between residual current protective devices . 39
535.4 Selectivity of RCD and OCPD . 39
535.5 Combined short-circuit protection of OCPDs . 39
536 Isolation and switching . 40
536.2 Isolation . 40
536.2.1 General . 40
536.2.2 Devices for isolation . 41
536.3 Switching-off for mechanical maintenance . 42
536.3.1 General . 42
536.3.2 Devices for switching-off for mechanical maintenance . 42
536.4 Emergency switching . 43
536.4.1 General . 43
536.4.2 Devices for emergency switching-off . 43
536.4.3 Devices for emergency stopping . 44
536.5 Functional switching (control) . 44
536.5.1 General . 44
536.5.2 Devices for functional switching . 44
537 Monitoring . 45
537.1 General . 45
537.1.1 Monitoring devices . 45
537.1.2 Selection of insulation monitoring devices (IMDs) . 45
537.1.3 Selection of residual current monitoring devices (RCMs) . 45
537.2 IT systems for continuity of supply . 45
537.2.1 General . 45
537.2.2 Insulation monitoring devices (IMDs) . 46
537.2.3 Installation of IMDs . 46
537.3 IT public distribution system . 46
– 4 – IEC 60364-5-
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