IEC 60898-3:2019

IEC 60898-3 ®
Edition 1.0 2019-04
INTERNATIONAL
STANDARD
Electrical accessories – Circuit-breakers for overcurrent protection for
household and similar installations –
Part 3: Circuit-breakers for DC operation

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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IEC 60898-3 ®
Edition 1.0 2019-04
INTERNATIONAL
STANDARD
Electrical accessories – Circuit-breakers for overcurrent protection for

household and similar installations –

Part 3: Circuit-breakers for DC operation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50 ISBN 978-2-8322-6676-2

– 2 – IEC 60898-3:2019 © IEC 2019
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 12
3 Terms and definitions . 12
3.1 Devices . 13
3.2 General terms . 13
3.3 Constructional elements . 15
3.4 Conditions of operation . 18
3.5 Characteristic quantities . 19
3.6 Definitions related to insulation co-ordination . 23
4 Classification . 25
4.1 General . 25
4.2 According to the number of poles . 25
4.3 According to the current direction through the poles. 25
4.4 According to the protection against external influences . 26
4.5 According to the method of mounting . 26
4.6 According to the methods of connection . 26
4.6.1 According to the fixation system . 26
4.6.2 According to the type of terminals . 26
4.7 According to the instantaneous tripping current (see 3.5.18) . 26
5 Characteristics of circuit-breakers. 26
5.1 List of characteristics . 26
5.2 Rated quantities . 27
5.2.1 Rated voltages . 27
5.2.2 Rated direct current (I ) . 27
n
5.2.3 Rated short-circuit capacity (I ) . 27
cn
5.2.4 Rated making and breaking capacity of an individual pole (I ) . 27
cn1
5.3 Standard and preferred values . 28
5.3.1 Preferred values of rated voltage . 28
5.3.2 Preferred values of rated current . 28
5.3.3 Values of rated short-circuit capacity . 28
5.3.4 Standard ranges of instantaneous tripping . 28
5.3.5 Standard value of rated impulse withstand voltage (U ) . 28
imp
6 Marking and other product information . 29
7 Standard conditions for operation in service . 30
7.1 General . 30
7.2 Ambient air temperature range . 30
7.3 Altitude . 31
7.4 Atmospheric conditions . 31
7.5 Conditions of installation . 31
7.6 Pollution degree . 31
8 Requirements for construction and operation . 31
8.1 Mechanical design . 31
8.1.1 General . 31
8.1.2 Mechanism . 31
8.1.3 Clearances and creepage distances (see Annex A) . 33

8.1.4 Screws, current-carrying parts and connections . 35
8.1.5 Terminals for external conductors . 36
8.1.6 Non-interchangeability . 38
8.1.7 Mechanical mounting of plug-in type circuit-breakers . 39
8.2 Protection against electric shock . 39
8.3 Dielectric properties and isolating capability . 39
8.3.1 General . 39
8.3.2 Dielectric properties . 40
8.3.3 Isolating capability . 40
8.3.4 Dielectric strength at rated impulse withstand voltage (U ) . 40
imp
8.4 Temperature rise . 40
8.4.1 Temperature rise limits . 40
8.4.2 Ambient air temperature . 40
8.5 Uninterrupted duty . 41
8.6 Automatic operation . 41
8.6.1 Standard time-current zone . 41
8.6.2 Conventional quantities . 42
8.6.3 Tripping characteristic . 42
8.7 Mechanical and electrical endurance . 42
8.8 Performance at short-circuit currents and at small DC currents . 43
8.9 Resistance to mechanical shock and impact . 43
8.10 Resistance to heat . 43
8.11 Resistance to abnormal heat and to fire . 43
8.12 Resistance to rusting . 43
8.13 Behaviour in case of making inrush current . 43
8.14 Power loss . 43
8.15 Requirement of small DC currents. 44
9 Tests . 44
9.1 Type tests and test sequences . 44
9.2 Test conditions . 45
9.3 Test of indelibility of marking . 46
9.4 Test of reliability of screws, current-carrying parts and connections . 46
9.5 Tests of reliability of screw-type terminals for external copper conductors. 47
9.6 Test of protection against electric shock . 49
9.7 Test of dielectric properties . 49
9.7.1 Resistance to humidity . 49
9.7.2 Insulation resistance of the main circuit . 50
9.7.3 Dielectric strength of the main circuit . 51
9.7.4 Insulation resistance and dielectric strength of auxiliary circuits. 51
9.7.5 Verification of impulse withstand voltages (across clearances and
across solid insulation) and of leakage current across open contacts . 52
9.8 Test of temperature rise and measurement of power loss . 55
9.8.1 Ambient air temperature . 55
9.8.2 Test procedure . 55
9.8.3 Measurement of the temperature of parts . 55
9.8.4 Temperature rise of a part . 55
9.8.5 Measurement of power loss . 55
9.9 28-day test . 56
9.10 Test of tripping characteristic . 56

– 4 – IEC 60898-3:2019 © IEC 2019
9.10.1 General . 56
9.10.2 Test of time-current characteristic . 56
9.10.3 Test of instantaneous tripping, of correct opening of the contacts and of
the trip-free function . 56
9.10.4 Test of effect of single-pole loading on the tripping characteristic of

multipole circuit-breakers . 57
9.10.5 Test of effect of ambient temperature on the tripping characteristic . 58
9.11 Verification of mechanical and electrical endurance . 58
9.11.1 General test conditions . 58
9.11.2 Test procedure . 58
9.11.3 Condition of the circuit-breaker after test . 59
9.12 Short-circuit tests . 59
9.12.1 General . 59
9.12.2 Values of test quantities . 60
9.12.3 Tolerances on test quantities . 60
9.12.4 Test circuit for short-circuit performance . 60
9.12.5 Time constant of the test circuits . 61
9.12.6 Measurement and verification of I t and of the peak current (I ) . 62
p
9.12.7 Calibration of the test circuit . 62
9.12.8 Interpretation of records . 62
9.12.9 Condition of the circuit-breaker for test . 62
9.12.10 Behaviour of the circuit-breaker during short-circuit tests . 64
9.12.11 Test procedure . 64
9.12.12 Verification of the circuit breaker after short circuit tests . 67
9.13 Mechanical stresses . 68
9.13.1 Mechanical shock . 68
9.13.2 Resistance to mechanical stresses and impact . 68
9.14 Test of resistance to heat . 71
9.15 Resistance to abnormal heat and to fire . 72
9.16 Test of resistance to rusting . 73
9.17 Verification of the behaviour in case of making inrush current . 73
9.17.1 General . 73
9.17.2 Values of the test quantities. 73
9.17.3 Limit deviations of the test quantities . 74
9.17.4 Test circuit for the determination of the withstand capacity against

making currents . 74
9.17.5 Testing for determination of the withstand capacity against making
currents . 75
Annex A (normative) Determination of clearances and creepage distances . 87
A.1 General . 87
A.2 Orientation and location of a creepage distance . 87
A.3 Creepage distances where more than one material is used . 87
A.4 Creepage distances split by floating conductive part . 87
A.5 Measurement of creepage distances and clearances . 87
Annex B (normative) Test sequences and number of samples necessary to prove

compliance with this document . 92
B.1 Test sequences . 92
B.2 Number of samples to be submitted for full test procedure and acceptance
criteria . 93
B.3 Number of samples to be submitted for simplified test procedure . 94

Annex C (informative) Co-ordination under short-circuit conditions between a circuit-
breaker and another short-circuit protective device (SCPD) associated in the same
circuit . 97
C.1 General . 97
C.2 Purpose . 97
C.3 General requirements for the co-ordination of a circuit-breaker with another
SCPD . 98
C.3.1 General consideration . 98
C.3.2 Take-over current . 98
C.3.3 Behaviour of C in association with another SCPD . 98
C.4 Type and characteristics of the associated SCPD . 98
C.5 Verification of selectivity . 99
C.6 Verification of back-up protection . 99
C.6.1 Determination of the take-over current . 99
C.6.2 Verification of back-up protection . 99
C.6.3 Tests for verification of back-up protection . 100
C.6.4 Results to be obtained . 101
Annex D (informative) Examples of terminals . 105
Annex E (informative) Correspondence between IEC and AWG copper conductors . 108
Annex F (normative) Arrangement for short-circuit test . 109
Annex G (normative) Routine tests . 112
G.1 General . 112
G.2 Tripping tests . 112
G.3 Verification of clearances between open contacts . 112
Annex H (normative) Particular requirements for circuit-breakers with screwless type

terminals for external copper conductors. 113
H.1 Scope . 113
H.2 Normative references . 113
H.3 Terms and definitions . 113
H.4 Classification . 114
H.5 Characteristics of circuit-breakers . 114
H.6 Marking and other product information . 114
H.7 Standard conditions for operation in service . 114
H.8 Requirements for construction and operation . 115
H.8.1 Connection or disconnection of conductors . 115
H.8.2 Dimensions of connectable conductors . 115
H.8.3 Connectable cross-sectional areas . 116
H.8.4 Insertion and disconnection of conductors . 116
H.8.5 Design and construction of terminals . 116
H.8.6 Resistance to ageing . 116
H.9 Tests . 116
H.9.1 Test of reliability of screwless terminals . 116
H.9.2 Tests of reliability of terminals for external conductors: mechanical
strength . 117
H.9.3 Cycling test. 118
H.10 Reference documents . 120
Annex I (normative) Particular requirements for circuit-breakers with flat quick-

connect terminations . 121
I.1 Scope . 121

– 6 – IEC 60898-3:2019 © IEC 2019
I.2 Normative references . 121
I.3 Terms and definitions . 121
I.4 Classification . 122
I.5 Characteristics of circuit-breakers . 122
I.6 Marking and other product information . 122
I.7 Standard conditions for operation in service . 122
I.8 Requirements for construction and operation . 122
I.8.1 Clearances and creepage distances (see Annex A) . 122
I.8.2 Terminals for external conductors . 123
I.9 Tests . 123
I.9.1 Mechanical overload-force . 123
Annex J (normative) Specific requirements for circuit-breakers with screw-type
terminals for external untreated aluminium conductors and with aluminium screw-type
terminals for use with copper or with aluminium conductors . 128
J.1 Scope . 128
J.2 Normative references . 128
J.3 Terms and definitions . 128
J.4 Classification . 129
J.5 Characteristics of circuit-breakers . 129
J.6 Marking and other product information . 129
J.7 Standard conditions for operation in service . 129
J.8 Constructional requirements . 130
J.9 Tests . 130
J.9.1 Test conditions . 132
J.9.2 Current cycling test . 132
J.10 Reference documents . 137
Bibliography . 138

Figure 1 – Thread forming tapping screw . 75
Figure 2 – Thread cutting tapping screw . 75
Figure 3 – Single-pole circuit-breaker or pole of multiple circuit breaker . 75
Figure 4 – Two-pole circuit-breaker with two protected poles . 76
Figure 5 – Three-pole circuit-breaker with two protected poles and non-polarized

protected M pole . 76
Figure 6 – Calibration of the test circuit in case of direct currents . 77
Figure 7 –Mechanical shock test apparatus (see 9.13.1) . 77
Figure 8 – Standard test finger (see 9.6) . 78
Figure 9 – Mechanical impact test apparatus (see 9.13.2) . 79
Figure 10 – Striking element for pendulum for mechanical impact test apparatus (see
9.13.2) . 80
Figure 11 – Mounting support for mechanical impact test (see 9.13.2) . 81
Figure 12 – Example of mounting for a rear fixed circuit-breaker for mechanical impact
test (see 9.13.2) . 82
Figure 13 – Example of mounting of a panel board type circuit-breaker for mechanical
impact test (see 9.13.2) . 83
Figure 14 – Application of force for mechanical test on a rail-mounted circuit-breaker
(see 9.13.2.4) . 84
Figure 15 – Ball-pressure test apparatus. 84

Figure 16 – Example of application of force for mechanical test on two-pole plug-in
circuit-breaker, the holding in position of which depends solely on the plug-in
connections (see 9.13.2.5) . 85
Figure 17 – Diagrammatic representation (see 9.15) . 86
Figure 18 – Impedance Z for test circuit in Figures 3, 4 and 5 for the simulation of
making currents . 86
Figure A.1 – Examples of methods of measuring creepage distances and clearances . 91
Figure C.1 – Overcurrent co-ordination between a circuit-breaker and a fuse or back-
up protection by a fuse – Operating characteristics . 102
Figure C.2 – Total selectivity between two circuit-breakers . 103
Figure C.3 – Back-up protection by a circuit-breaker – Operating characteristics . 104
Figure D.1 – Examples of pillar terminals . 105
Figure D.2 – Examples of screw terminals and stud terminals . 106
Figure D.3 – Examples of saddle terminals . 107
Figure D.4 – Examples of lug terminals . 107
Figure F.1 – Test arrangement . 110
Figure F.2 – Grid circuit . 111
Figure F.3 – Grid circuit . 111
Figure H.1 – Connecting samples . 118
Figure H.2 – Examples of screwless-type terminals . 120
Figure I.1 – Example of position of the thermocouple for measurement of the

temperature rise . 124
Figure I.2 – Dimensions of male tabs . 125
Figure I.3 – Dimensions of round dimple detents (see Figure I.2) . 126
Figure I.4 – Dimensions of rectangular dimple detents (see Figure I.2) . 126
Figure I.5 – Dimensions of hole detents . 126
Figure I.6 – Dimensions of female connectors . 127
Figure J.1 – General arrangement for the test . 136
Figure J.2 . 136
Figure J.3 . 137
Figure J.4 . 137
Figure J.5 . 137
Figure J.6 . 137

Table 1 – Preferred values of rated voltage and corresponding supply systems . 28
Table 2 – Ranges of instantaneous tripping . 28
Table 3 – Minimum clearances and creepage distances . 34
Table 4 – Connectable cross-sections of copper conductors for screw-type terminals . 37
Table 5 – Temperature rise values . 40
Table 6 – Time-current operating characteristics . 41
Table 7 – Maximum power loss per pole . 44
Table 8 – List of type tests . 44
Table 9 – Cross-sectional areas (S) of test copper conductors corresponding to the
rated currents . 46
Table 10 – Screw thread diameters and applied torques . 47

– 8 – IEC 60898-3:2019 © IEC 2019
Table 11 – Pulling forces . 48
Table 12 – Test voltage of auxiliary circuits . 52
Table 13 – Test voltage for verification of impulse withstand voltage . 54
Table 14 – Test voltage for verifying the suitability for isolation, referred to the rated
impulse withstand voltage of the circuit breakers and the altitude where the test is

carried out . 54
Table 15 – Applicability of tests . 60
Table 16 – Ratio k between service short-circuit capacity (I ) and rated short-circuit
cs
capacity (I ) . 66
cn
Table B.1 – Test sequences . 92
Table B.2 – Number of samples for full test procedure . 94
Table B.3 – Reduction of samples for series of circuit-breakers having different
numbers of poles . 95
Table B.4 – Test sequences for a series of circuit-breakers being of different
instantaneous tripping classifications . 96
Table H.1 – Connectable conductors . 115
Table H.2 – Cross-sections of copper conductors connectable to screwless-type
terminals . 116
Table H.3 – Pull forces . 117
Table I.1 – Informative table on colour code of female connectors in relationship with
the cross section of the conductor . 122
Table I.2 – Overload test forces . 123
Table I.3 – Dimensions of tabs . 124
Table I.4 – Dimensions of female connectors . 127
Table J.1 – Marking for terminals . 129
Table J.2 – Connectable cross-sections of aluminium conductors for screw-type
terminals . 130
Table J.3 – List of tests according to the material of conductors and terminals. 131
Table J.4 – Connectable conductors and their theoretical diameters . 131
Table J.5 – Cross sections (S) of aluminium test conductors corresponding to the rated
currents . 132
Table J.6 – Test conductor length . 133
Table J.7 – Equalizer and busbar dimensions . 133
Table J.8 – Test current as a function of rated current . 135
Table J.9 – Example of calculation for determining the average temperature deviation D . 135

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ACCESSORIES – CIRCUIT-BREAKERS FOR
OVERCURRENT PROTECTION FOR HOUSEHOLD
AND SIMILAR INSTALLATIONS –
Part 3: Circuit-breakers for DC operation

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60898-3 has been prepared by sub-committee 23E: Circuit-
breakers and similar equipment for household use, of IEC technical committee 23: Electrical
accessories.
The text of this International Standard is based on the following documents:
FDIS Report on voting
23E/1122FDIS 23E/1126/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 10 – IEC 60898-3:2019 © IEC 2019
A li
...

IEC 60898-3 ®
Edition 1.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical accessories – Circuit-breakers for overcurrent protection for
household and similar installations –
Part 3: Circuit-breakers for DC operation

Petit appareillage électrique – Disjoncteurs pour la protection contre les
surintensités pour installations domestiques et analogues –
Partie 3: Disjoncteurs pour le fonctionnement en courant continu
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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International Standards for all electrical, electronic and related technologies.

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IEC 60898-3 ®
Edition 1.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical accessories – Circuit-breakers for overcurrent protection for

household and similar installations –

Part 3: Circuit-breakers for DC operation

Petit appareillage électrique – Disjoncteurs pour la protection contre les

surintensités pour installations domestiques et analogues –

Partie 3: Disjoncteurs pour le fonctionnement en courant continu

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.50  ISBN 978-2-8322-7306-7

– 2 – IEC 60898-3:2019 © IEC 2019
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 12
3 Terms and definitions . 12
3.1 Devices . 13
3.2 General terms . 13
3.3 Constructional elements . 15
3.4 Conditions of operation . 18
3.5 Characteristic quantities . 19
3.6 Definitions related to insulation co-ordination . 23
4 Classification . 25
4.1 General . 25
4.2 According to the number of poles . 25
4.3 According to the current direction through the poles. 25
4.4 According to the protection against external influences . 26
4.5 According to the method of mounting . 26
4.6 According to the methods of connection . 26
4.6.1 According to the fixation system . 26
4.6.2 According to the type of terminals . 26
4.7 According to the instantaneous tripping current (see 3.5.18) . 26
5 Characteristics of circuit-breakers. 26
5.1 List of characteristics . 26
5.2 Rated quantities . 27
5.2.1 Rated voltages . 27
5.2.2 Rated direct current (I ) . 27
n
5.2.3 Rated short-circuit capacity (I ) . 27
cn
5.2.4 Rated making and breaking capacity of an individual pole (I ) . 27
cn1
5.3 Standard and preferred values . 28
5.3.1 Preferred values of rated voltage . 28
5.3.2 Preferred values of rated current . 28
5.3.3 Values of rated short-circuit capacity . 28
5.3.4 Standard ranges of instantaneous tripping . 28
5.3.5 Standard value of rated impulse withstand voltage (U ) . 28
imp
6 Marking and other product information . 29
7 Standard conditions for operation in service . 30
7.1 General . 30
7.2 Ambient air temperature range . 30
7.3 Altitude . 31
7.4 Atmospheric conditions . 31
7.5 Conditions of installation . 31
7.6 Pollution degree . 31
8 Requirements for construction and operation . 31
8.1 Mechanical design . 31
8.1.1 General . 31
8.1.2 Mechanism . 31
8.1.3 Clearances and creepage distances (see Annex A) . 33

8.1.4 Screws, current-carrying parts and connections . 35
8.1.5 Terminals for external conductors . 36
8.1.6 Non-interchangeability . 38
8.1.7 Mechanical mounting of plug-in type circuit-breakers . 39
8.2 Protection against electric shock . 39
8.3 Dielectric properties and isolating capability . 39
8.3.1 General . 39
8.3.2 Dielectric properties . 40
8.3.3 Isolating capability . 40
8.3.4 Dielectric strength at rated impulse withstand voltage (U ) . 40
imp
8.4 Temperature rise . 40
8.4.1 Temperature rise limits . 40
8.4.2 Ambient air temperature . 40
8.5 Uninterrupted duty . 41
8.6 Automatic operation . 41
8.6.1 Standard time-current zone . 41
8.6.2 Conventional quantities . 42
8.6.3 Tripping characteristic . 42
8.7 Mechanical and electrical endurance . 42
8.8 Performance at short-circuit currents and at small DC currents . 43
8.9 Resistance to mechanical shock and impact . 43
8.10 Resistance to heat . 43
8.11 Resistance to abnormal heat and to fire . 43
8.12 Resistance to rusting . 43
8.13 Behaviour in case of making inrush current . 43
8.14 Power loss . 43
8.15 Requirement of small DC currents. 44
9 Tests . 44
9.1 Type tests and test sequences . 44
9.2 Test conditions . 45
9.3 Test of indelibility of marking . 46
9.4 Test of reliability of screws, current-carrying parts and connections . 46
9.5 Tests of reliability of screw-type terminals for external copper conductors. 47
9.6 Test of protection against electric shock . 49
9.7 Test of dielectric properties . 49
9.7.1 Resistance to humidity . 49
9.7.2 Insulation resistance of the main circuit . 50
9.7.3 Dielectric strength of the main circuit . 51
9.7.4 Insulation resistance and dielectric strength of auxiliary circuits. 52
9.7.5 Verification of impulse withstand voltages (across clearances and
across solid insulation) and of leakage current across open contacts . 52
9.8 Test of temperature rise and measurement of power loss . 55
9.8.1 Ambient air temperature . 55
9.8.2 Test procedure . 55
9.8.3 Measurement of the temperature of parts . 55
9.8.4 Temperature rise of a part . 55
9.8.5 Measurement of power loss . 56
9.9 28-day test . 56
9.10 Test of tripping characteristic . 56

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9.10.1 General . 56
9.10.2 Test of time-current characteristic . 56
9.10.3 Test of instantaneous tripping, of correct opening of the contacts and of
the trip-free function . 57
9.10.4 Test of effect of single-pole loading on the tripping characteristic of

multipole circuit-breakers . 58
9.10.5 Test of effect of ambient temperature on the tripping characteristic . 58
9.11 Verification of mechanical and electrical endurance . 58
9.11.1 General test conditions . 58
9.11.2 Test procedure . 58
9.11.3 Condition of the circuit-breaker after test . 59
9.12 Short-circuit tests . 60
9.12.1 General . 60
9.12.2 Values of test quantities . 60
9.12.3 Tolerances on test quantities . 60
9.12.4 Test circuit for short-circuit performance . 61
9.12.5 Time constant of the test circuits . 62
9.12.6 Measurement and verification of I t and of the peak current (I ) . 62
p
9.12.7 Calibration of the test circuit . 62
9.12.8 Interpretation of records . 62
9.12.9 Condition of the circuit-breaker for test . 62
9.12.10 Behaviour of the circuit-breaker during short-circuit tests . 64
9.12.11 Test procedure . 64
9.12.12 Verification of the circuit breaker after short circuit tests . 67
9.13 Mechanical stresses . 68
9.13.1 Mechanical shock . 68
9.13.2 Resistance to mechanical stresses and impact . 68
9.14 Test of resistance to heat . 71
9.15 Resistance to abnormal heat and to fire . 72
9.16 Test of resistance to rusting . 73
9.17 Verification of the behaviour in case of making inrush current . 73
9.17.1 General . 73
9.17.2 Values of the test quantities. 73
9.17.3 Limit deviations of the test quantities . 74
9.17.4 Test circuit for the determination of the withstand capacity against

making currents . 74
9.17.5 Testing for determination of the withstand capacity against making
currents . 74
Annex A (normative) Determination of clearances and creepage distances . 87
A.1 General . 87
A.2 Orientation and location of a creepage distance . 87
A.3 Creepage distances where more than one material is used . 87
A.4 Creepage distances split by floating conductive part . 87
A.5 Measurement of creepage distances and clearances . 87
Annex B (normative) Test sequences and number of samples necessary to prove

compliance with this document . 92
B.1 Test sequences . 92
B.2 Number of samples to be submitted for full test procedure and acceptance
criteria . 93
B.3 Number of samples to be submitted for simplified test procedure . 94

Annex C (informative) Co-ordination under short-circuit conditions between a circuit-
breaker and another short-circuit protective device (SCPD) associated in the same
circuit . 97
C.1 General . 97
C.2 Purpose . 98
C.3 General requirements for the co-ordination of a circuit-breaker with another
SCPD . 98
C.3.1 General consideration . 98
C.3.2 Take-over current . 98
C.3.3 Behaviour of C in association with another SCPD . 98
C.4 Type and characteristics of the associated SCPD . 98
C.5 Verification of selectivity . 99
C.6 Verification of back-up protection . 99
C.6.1 Determination of the take-over current . 99
C.6.2 Verification of back-up protection . 99
C.6.3 Tests for verification of back-up protection . 100
C.6.4 Results to be obtained . 101
Annex D (informative) Examples of terminals . 105
Annex E (informative) Correspondence between IEC and AWG copper conductors . 108
Annex F (normative) Arrangement for short-circuit test . 109
Annex G (normative) Routine tests . 112
G.1 General . 112
G.2 Tripping tests . 112
G.3 Verification of clearances between open contacts . 112
Annex H (normative) Particular requirements for circuit-breakers with screwless type

terminals for external copper conductors. 113
H.1 Scope . 113
H.2 Normative references . 113
H.3 Terms and definitions . 113
H.4 Classification . 114
H.5 Characteristics of circuit-breakers . 114
H.6 Marking and other product information . 114
H.7 Standard conditions for operation in service . 114
H.8 Requirements for construction and operation . 115
H.8.1 Connection or disconnection of conductors . 115
H.8.2 Dimensions of connectable conductors . 115
H.8.3 Connectable cross-sectional areas . 116
H.8.4 Insertion and disconnection of conductors . 116
H.8.5 Design and construction of terminals . 116
H.8.6 Resistance to ageing . 116
H.9 Tests . 116
H.9.1 Test of reliability of screwless terminals . 116
H.9.2 Tests of reliability of terminals for external conductors: mechanical
strength . 117
H.9.3 Cycling test. 118
H.10 Reference documents . 120
Annex I (normative) Particular requirements for circuit-breakers with flat quick-

connect terminations . 121
I.1 Scope . 121

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I.2 Normative references . 121
I.3 Terms and definitions . 121
I.4 Classification . 122
I.5 Characteristics of circuit-breakers . 122
I.6 Marking and other product information . 122
I.7 Standard conditions for operation in service . 122
I.8 Requirements for construction and operation . 122
I.8.1 Clearances and creepage distances (see Annex A) . 122
I.8.2 Terminals for external conductors . 123
I.9 Tests . 123
I.9.1 Mechanical overload-force . 123
Annex J (normative) Specific requirements for circuit-breakers with screw-type
terminals for external untreated aluminium conductors and with aluminium screw-type
terminals for use with copper or with aluminium conductors . 128
J.1 Scope . 128
J.2 Normative references . 128
J.3 Terms and definitions . 128
J.4 Classification . 129
J.5 Characteristics of circuit-breakers . 129
J.6 Marking and other product information . 129
J.7 Standard conditions for operation in service . 129
J.8 Constructional requirements . 130
J.9 Tests . 130
J.9.1 Test conditions . 132
J.9.2 Current cycling test . 132
J.10 Reference documents . 137
Bibliography . 138

Figure 1 – Thread forming tapping screw . 75
Figure 2 – Thread cutting tapping screw . 75
Figure 3 – Single-pole circuit-breaker or pole of multiple circuit breaker . 75
Figure 4 – Two-pole circuit-breaker with two protected poles . 76
Figure 5 – Three-pole circuit-breaker with two protected poles and non-polarized

protected M-pole . 76
Figure 6 – Calibration of the test circuit in case of direct currents . 77
Figure 7 – Mechanical shock test apparatus (see 9.13.1) . 77
Figure 8 – Standard test finger (see 9.6) . 78
Figure 9 – Mechanical impact test apparatus (see 9.13.2) . 79
Figure 10 – Striking element for pendulum for mechanical impact test apparatus (see
9.13.2) . 80
Figure 11 – Mounting support for mechanical impact test (see 9.13.2) . 81
Figure 12 – Example of mounting for a rear fixed circuit-breaker for mechanical impact
test (see 9.13.2) . 82
Figure 13 – Example of mounting of a panel board type circuit-breaker for mechanical
impact test (see 9.13.2) . 83
Figure 14 – Application of force for mechanical test on a rail-mounted circuit-breaker
(see 9.13.2.4) . 84
Figure 15 – Ball-pressure test apparatus. 84

Figure 16 – Example of application of force for mechanical test on two-pole plug-in
circuit-breaker, the holding in position of which depends solely on the plug-in
connections (see 9.13.2.5) . 85
Figure 17 – Diagrammatic representation (see 9.15) . 86
Figure 18 – Impedance Z for test circuit in Figures 3, 4 and 5 for the simulation of
making currents . 86
Figure A.1 – Examples of methods of measuring creepage distances and clearances . 91
Figure C.1 – Overcurrent co-ordination between a circuit-breaker and a fuse or back-
up protection by a fuse – Operating characteristics . 102
Figure C.2 – Total selectivity between two circuit-breakers . 103
Figure C.3 – Back-up protection by a circuit-breaker – Operating characteristics . 104
Figure D.1 – Examples of pillar terminals . 105
Figure D.2 – Examples of screw terminals and stud terminals . 106
Figure D.3 – Examples of saddle terminals . 107
Figure D.4 – Examples of lug terminals . 107
Figure F.1 – Test arrangement . 110
Figure F.2 – Grid circuit . 110
Figure F.3 – Grid circuit . 111
Figure H.1 – Connecting samples . 118
Figure H.2 – Examples of screwless-type terminals . 120
Figure I.1 – Example of position of the thermocouple for measurement of the

temperature rise . 124
Figure I.2 – Dimensions of male tabs . 125
Figure I.3 – Dimensions of round dimple detents (see Figure I.2) . 126
Figure I.4 – Dimensions of rectangular dimple detents (see Figure I.2) . 126
Figure I.5 – Dimensions of hole detents . 126
Figure I.6 – Dimensions of female connectors . 127
Figure J.1 – General arrangement for the test . 136
Figure J.2 . 136
Figure J.3 . 137
Figure J.4 . 137
Figure J.5 . 137
Figure J.6 . 137

Table 1 – Preferred values of rated voltage and corresponding supply systems . 28
Table 2 – Ranges of instantaneous tripping . 28
Table 3 – Minimum clearances and creepage distances . 34
Table 4 – Connectable cross-sections of copper conductors for screw-type terminals . 37
Table 5 – Temperature rise values . 40
Table 6 – Time-current operating characteristics . 41
Table 7 – Maximum power loss per pole . 44
Table 8 – List of type tests . 44
Table 9 – Cross-sectional areas (S) of test copper conductors corresponding to the
rated currents . 46
Table 10 – Screw thread diameters and applied torques . 47

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Table 11 – Pulling forces . 48
Table 12 – Test voltage of auxiliary circuits . 52
Table 13 – Test voltage for verification of impulse withstand voltage . 54
Table 14 – Test voltage for verifying the suitability for isolation, referred to the rated
impulse withstand voltage of the circuit breakers and the altitude where the test is

carried out . 54
Table 15 – Applicability of tests . 60
Table 16 – Ratio k between service short-circuit capacity (I ) and rated short-circuit
cs
capacity (I ) . 66
cn
Table B.1 – Test sequences . 92
Table B.2 – Number of samples for full test procedure . 94
Table B.3 – Reduction of samples for series of circuit-breakers having different
numbers of poles . 95
Table B.4 – Test sequences for a series of circuit-breakers being of different
instantaneous tripping classifications . 96
Table H.1 – Connectable conductors . 115
Table H.2 – Cross-sections of copper conductors connectable to screwless-type
terminals . 116
Table H.3 – Pull forces . 117
Table I.1 – Informative table on colour code of female connectors in relationship with
the cross section of the conductor . 122
Table I.2 – Overload test forces . 123
Table I.3 – Dimensions of tabs . 124
Table I.4 – Dimensions of female connectors . 127
Table J.1 – Marking for terminals . 129
Table J.2 – Connectable cross-sections of aluminium conductors for screw-type
terminals . 130
Table J.3 – List of tests according to the material of conductors and terminals. 131
Table J.4 – Connectable conductors and their theoretical diameters . 131
Table J.5 – Cross sections (S) of aluminium test conductors corresponding to the rated
currents . 132
Table J.6 – Test conductor length . 133
Table J.7 – Equalizer and busbar dimensions . 133
Table J.8 – Test current as a function of rated current . 135
Table J.9 – Example of calculation for determining the average temperature deviation D . 135

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ACCESSORIES – CIRCUIT-BREAKERS FOR
OVERCURRENT PROTECTION FOR HOUSEHOLD
AND SIMILAR INSTALLATIONS –
Part 3: Circuit-breakers for DC operation

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardiza
...