IEC 62052-31:2024

IEC 62052-31 ®
Edition 2.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electricity metering equipment – General requirements, tests and test
conditions –
Part 31: Product safety requirements and tests

Équipement de comptage de l'électricité – Exigences générales, essais et
conditions d'essai –
Partie 31: Exigences et essais sur la sécurité de produit
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IEC 62052-31 ®
Edition 2.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electricity metering equipment – General requirements, tests and test

conditions –
Part 31: Product safety requirements and tests

Équipement de comptage de l'électricité – Exigences générales, essais et

conditions d'essai –
Partie 31: Exigences et essais sur la sécurité de produit

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.080, 91.140.50 ISBN 978-2-8322-9302-7

– 2 – IEC 62052-31:2024 © IEC 2024
CONTENTS
FOREWORD . 9
INTRODUCTION . 12
1 Scope . 13
1.1 General . 13
1.2 Aspects included in scope . 14
1.3 Aspects excluded from scope . 15
1.4 Verification. 15
1.5 Environmental conditions . 15
1.5.1 Normal environmental conditions . 15
1.5.2 Extended environmental conditions . 16
1.5.3 Extreme environmental conditions . 16
2 Normative references . 17
3 Terms and definitions . 19
3.1 Equipment and states of equipment . 19
3.2 Parts, accessories, and functional elements . 19
3.3 Quantities . 25
3.4 Tests . 28
3.5 Safety terms . 28
3.6 Insulation . 33
3.7 Terms related to switches of metering equipment . 37
4 Tests . 39
4.1 General . 39
4.2 Type test – sequence of tests . 40
4.3 Reference test conditions. 40
4.3.1 Atmospheric conditions . 40
4.3.2 State of the equipment . 41
4.4 Testing in single fault condition . 44
4.4.1 General . 44
4.4.2 Application of fault conditions . 44
4.4.3 Duration of tests . 47
4.4.4 Conformity after application of fault conditions . 47
5 Information and marking requirements . 47
5.1 General . 47
5.2 Labels, signs and signals . 50
5.2.1 General . 50
5.2.2 Durability of markings . 53
5.3 Information for selection . 53
5.3.1 General . 53
5.3.2 General information . 53
5.3.3 Information specific for meters . 54
5.3.4 Information specific for stand-alone tariff and load control equipment . 54
5.3.5 Information related to LCS . 54
5.4 General information for installation and commissioning . 55
5.4.1 General . 55
5.4.2 Handling and mounting . 55
5.4.3 Enclosure . 55

5.4.4 Connections . 56
5.4.5 Auxiliary power supply . 58
5.4.6 Supply for external devices . 58
5.4.7 Self-consumption . 59
5.4.8 Commissioning . 59
5.5 General information for use . 59
5.5.1 General . 59
5.5.2 Display, push buttons and other controls . 59
5.5.3 Switches . 60
5.5.4 Connection to user's equipment . 60
5.6 General information for maintenance . 60
5.6.1 Maintenance instructions . 60
5.6.2 Cleaning . 60
5.6.3 Batteries . 60
6 Protection against electrical shock . 61
6.1 General requirements . 61
6.2 Determination of accessible parts . 62
6.2.1 General . 62
6.2.2 Examination . 62
6.2.3 Openings above parts that are hazardous live . 63
6.2.4 Openings for pre-set controls . 63
6.2.5 Wiring terminals . 63
6.3 Limit values for accessible parts . 64
6.3.1 General . 64
6.3.2 Levels in normal condition . 64
6.3.3 Levels in single fault condition . 65
6.4 Primary means of protection (protection against direct contact) . 67
6.4.1 General . 67
6.4.2 Equipment case . 68
6.4.3 Basic insulation . 68
6.4.4 Impedance . 68
6.5 Additional means of protection in case of single fault conditions (protection
against indirect contact) . 68
6.5.1 General . 68
6.5.2 Protective bonding . 69
6.5.3 Supplementary insulation and reinforced insulation . 72
6.5.4 Protective impedance . 73
6.5.5 Automatic disconnection of the supply . 73
6.5.6 Current- or voltage-limiting device . 73
6.6 Connection to external circuits . 74
6.6.1 General . 74
6.6.2 Terminals for external circuits . 74
6.6.3 Terminals for stranded conductors . 74
6.7 Insulation requirements . 75
6.7.1 General – electric stresses, overvoltages and working voltages . 75
6.7.2 The nature of insulation . 78
6.7.3 Insulation requirements for mains circuits . 81
6.7.4 Insulation requirements for non-mains circuits . 90

– 4 – IEC 62052-31:2024 © IEC 2024
6.7.5 Insulation in circuits with special voltage values not addressed in 6.7.3
or 6.7.4 . 97
6.7.6 Reduction of transient overvoltages by the use of overvoltage limiting
devices . 104
6.7.7 Insulation requirements between circuits and parts . 104
6.8 Constructional requirements for protection against electric shock . 108
6.8.1 General . 108
6.8.2 Insulating materials . 108
6.8.3 Color coding . 108
6.8.4 Equipment case . 108
6.8.5 Terminal blocks . 109
6.8.6 Insulating materials of SCS and LCS . 109
6.8.7 Terminals . 110
6.8.8 Requirements for current circuits . 112
6.9 Safety related electrical tests . 119
6.9.1 Overview . 119
6.9.2 Test conditions . 121
6.9.3 Dielectric test methods . 123
6.9.4 Dielectric testing on complete equipment . 126
6.9.5 Dielectric tests on sub-assemblies . 132
6.9.6 Electrical tests on current circuits of directly connected meters without
SCS . 137
6.9.7 Electrical tests on current circuits of directly connected meters with

SCS . 137
6.9.8 Electrical tests on LCS . 144
6.9.9 Cemented joints test . 147
6.9.10 Thermal cycling . 148
7 Protection against mechanical hazards . 148
7.1 General . 148
7.2 Sharp edges . 148
7.3 Provisions for lifting and carrying . 149
7.4 Wall mounting . 149
8 Resistance to mechanical stresses . 150
8.1 General . 150
8.2 Spring hammer test . 150
9 Protection against spread of fire . 150
9.1 General . 150
9.2 Eliminating or reducing the sources of ignition within the equipment . 151
9.3 Containment of fire within the equipment, should it occur . 151
9.3.1 General . 151
9.3.2 Construction requirements . 152
9.4 Limited-energy circuit . 153
9.5 Overcurrent protection . 154
10 Equipment temperature limits and resistance to heat . 154
10.1 Surface temperature limits for protection against burns . 154
10.2 Temperature limits for terminals . 155
10.3 Temperatures of internal parts . 156
10.4 Temperature test . 158
10.5 Resistance to heat . 159

10.5.1 Non-metallic enclosures . 159
10.5.2 Insulating materials . 160
11 Protection against penetration of dust and water . 160
11.1 General . 160
11.2 Test for protection against ingress of dust and foreign objects . 161
11.3 Test for protection against ingress of water . 161
12 Protection against liberated gases and substances explosion and implosion . 162
12.1 Batteries and battery charging . 162
12.1.1 Mounting of batteries . 162
12.1.2 Battery circuits . 162
12.1.3 Tests related to batteries and charging circuits . 163
13 Components and sub-assemblies . 164
13.1 General . 164
13.2 Mains transformers tested outside equipment . 165
13.3 Printed wiring boards . 165
13.4 Components bridging insulation . 166
13.5 Surge protective devices (SPDs, transient overvoltage limiting circuits) . 166
13.5.1 General use of SPDs . 166
13.5.2 SPD overheating test . 167
13.6 Capacitors . 167
14 Hazards resulting from application – Reasonably foreseeable misuse . 168
15 Risk assessment . 168
Annex A (normative) Measuring circuits for touch current . 169
A.1 Measuring circuit for AC with frequencies up to 1 MHz and for DC . 169
A.2 Measuring circuits for sinusoidal AC with frequencies up to 100 Hz and for
DC . 170
A.3 Current measuring circuit for electrical burns at high frequencies . 170
A.4 Current measuring circuit for wet location . 171
Annex B (informative) Examples for insulation between parts . 173
B.1 General . 173
B.2 Example of a meter protected by reinforced insulation . 173
B.3 Example of a meter protected by double insulation . 175
Annex C (informative) Examples for directly connected meters equipped with SCS and

LCS . 177
Annex D (normative) Test circuit diagram for the test of long-term overvoltage
withstand . 179
Annex E (normative) Test circuit diagram for short current test on the current circuit of
directly connected meters . 180
Annex F (informative) Examples of voltage tests . 182
F.1 General . 182
F.2 Example of a directly connected meter with SCS . 182
F.3 Example of a transformer operated meter with auxiliary power supply . 186
F.4 Example of an LPCT-operated meter with direct voltage connections . 191
Annex G (normative) Additional AC voltage tests for electromechanical meters . 196
Annex H (normative) Test equipment for cable flexion and pull test . 197
Annex I (normative) Routine tests . 199
I.1 General . 199
I.2 Protective earth . 199

– 6 – IEC 62052-31:2024 © IEC 2024
I.3 High-voltage test for mains circuits . 199
I.4 Mains circuits with voltage-limiting devices . 200
Annex J (informative) Examples of battery protection . 201
Annex K (informative) Transient overvoltage requirements in TC 13 standards . 202
Annex L (informative) Electricity meters in LVDC systems . 203
Annex M (informative) Component standards . 205
Bibliography . 206

Figure 1 – Measurements through openings in enclosures . 63
Figure 2 – Capacitance level versus voltage in normal condition and single fault
condition (see 6.3.2c) and 6.3.3c)) . 66
Figure 3 – Maximum duration of short-term accessible voltages in single fault
condition (see 6.3.3a)) . 67
Figure 4 – Acceptable arrangements of protection means against electric shock . 69
Figure 5 – Examples of binding screw assemblies . 71
Figure 6 – Distance between conductors on an interface between two layers . 88
Figure 7 – Distance between adjacent conductors along an interface of an inner layer . 88
Figure 8 – Distance between adjacent conductors located between the same two
layers. 90
Figure 9 – Example of recurring peak voltage . 102
Figure 10 – Flowchart of safety related electrical tests – part 1 . 120
Figure 11 – Flowchart of safety related electrical tests – part 2 . 121
Figure 12 – Flowchart to explain the requirements for protection against the spread of fire . 151
Figure 13 – Flowchart for conformity options 13.1 a), b), c) and d) . 165
Figure A.1 – Measuring circuit for AC with frequencies up to 1 MHz and for DC . 169
Figure A.2 – Measuring circuits for sinusoidal AC with frequencies up to 100 Hz and for
DC . 170
Figure A.3 – Current measuring circuit for electrical burns . 171
Figure A.4 – Current measuring circuit for wet location . 172
Figure B.1 – Insulation between parts – example of a meter protected by reinforced
insulation . 174
Figure B.2 – Insulation between parts – example of a meter protected by double
insulation . 175
Figure C.1 – Single phase two wire meter with UC2 SCS and 25A LCS . 177
Figure C.2 – Three phase four wire meter with UC2 SCS and 2A ACS . 178
Figure D.1 – Circuit for three-phase four-wire meters to simulate long term
overvoltage, voltage moved to L3. 179
Figure D.2 – Voltages at the meter under test . 179
Figure E.1 – Test circuit for verification of short-time withstand current test on current
circuits with and without SCS (meter example is with SCS) . 180
Figure E.2 – Example of short-circuit carrying test record in the case of a single-pole

equipment on single-phase AC . 181
Figure F.1 – Example terminal arrangement of a directly connected meter with SCS . 182
Figure F.2 – Example terminal arrangement of a transformer operated meter with
auxiliary power supply . 186
Figure F.3 – Example terminal arrangement of a LPCT-operated meter with direct
voltage connections . 191

Figure H.1 – Test equipment for cable flexion and pull test (see 6.8.7.3) . 197
Figure J.1 – Non-rechargeable battery protection . 201
Figure J.2 – Rechargeable battery protection . 201
Figure L.1 – Unipolar, balanced and bipolar DC systems . 203

Table 1 – Test copper conductors for current and switch terminals . 43
Table 2 – Information requirements . 48
Table 3 – IEC 60417-DB-12M and ISO 7000:2019 symbols that may be used on
metering equipment . 52
Table 4 – Tightening torque for binding screw assemblies . 72
Table 5 – Multiplication factors for clearance for altitudes up to 5 000 m . 78
Table 6 – Overview of clauses specifying requirements for insulations . 81
Table 7 – Nominal / rated voltages and rated impulse voltages . 82
Table 8 – Clearances for mains circuits . 84
Table 9 – Creepage distances for mains circuits . 85
Table 10 – Test voltages for solid insulation in mains circuits . 86
Table 11 – Test voltages for testing long-term stress of solid insulation in mains circuits . 87
Table 12 – Minimum values for distance or thickness of solid insulation in mains circuits . 89
Table 13 – Clearances and test voltages for non-mains circuits derived from mains

circuits of overvoltage category III . 92
Table 14 – Creepage distances for non-mains circuits and functional insulation . 94
Table 15 – Minimum values for distance or thickness (see 6.7.4.4.2 to 6.7.4.4.4) . 96
Table 16 – Clearance values for the calculation of 6.7.5.2 . 99
Table 17 – Test voltages based on clearances . 100
Table 18 – Clearances for basic insulation in circuits having recurring peak voltages . 103
Table 19 – Isolation classes for non-mains circuits . 105
Table 20 – Insulation requirements between circuits . 106
Table 21 – Summary of requirements for current circuits of directly connected meters
without SCS . 115
Table 22 – Summary of requirements for current circuits of directly connected meters
with SCS . 116
Table 23 – Summary of requirements for LCS . 118
Table 24 – Correction factors according to test site altitude for test voltages for

clearances . 122
Table 25 – AC voltage test . 130
Table 26 – DC voltage test . 131
Table 27 – Voltage tests for verification of clearance in mains circuits . 133
Table 28 – Voltage tests for verification of clearance in non-mains circuits . 133
DC test voltages equal to the AC test voltages from Table 13 . 133
Table 29 – Voltage tests for verification of clearance in circuits with special voltage
values . 134
Table 30 – Voltage tests for verification of solid insulation in mains circuits . 135
Table 31 – Voltage tests for verification of solid insulation in non-mains circuits . 136
Table 32 – Voltage tests for verification of solid insulation in circuits with special
voltage values . 136

– 8 – IEC 62052-31:2024 © IEC 2024
Table 33 – Test sequence and sample plan for SCS . 138
Table 34 – Power factor ranges of the test circuit . 141
Table 35 – Test sequence and sample plan for LCS . 144
Table 36 – Limits for power sources without an overcurrent protective device . 153
Table 37 – Limits for power sources with an overcurrent protection device . 154
Table 38 – Surface temperature limits in normal condition . 155
Table 39 – Temperature limits for terminals . 156
Table 40 – Maximum measured temperatures for internal materials and components . 157
Table F.1 – Application of impulse test voltages according to 6.9.4.4 . 183
Table F.2 – Application of AC power frequency test voltages according to 6.9.4.5 or DC
test voltages according to 6.9.4.6 . 183
Table F.3 – Application of AC long-term overvoltage test voltages according to
6.9.4.3.2 . 184
Table F.4 – Application of surge test voltages according to 6.9.4.7 . 185
Table F.5 – Application of impulse test voltages according to 6.9.4.4 . 187
Table F.6 – Application of AC power frequency test voltages according to 6.9.4.5 or DC
test voltages according to 6.9.4.6 . 188
Table F.7 – Application of AC long-term overvoltage test voltages according to
6.9.4.3.2 . 189
Table F.8 – Application of surge test voltages according to 6.9.4.7 . 190
Table F.9 – Application of impulse test voltages according to 6.9.4.4 . 192
Table F.10 – Application of AC power frequency test voltages according to 6.9.4.5 or
DC test voltages according to 6.9.4.6. 193
Table F.11 – Application of AC long-term overvoltage test voltages according to
6.9.4.3.2 . 194
Table F.12 – Application of surge test voltages according to 6.9.4.7 . 195
Table G.1 – AC voltage tests of electromechanical meters . 196
Table H.1 – Test values for flexion and pull-out tests for round copper conductors . 198
Table L.1 – Voltage between lines (unipolar systems) or line and midpoint (bipolar
systems) for installation domain . 204
Table L.2 – Voltage between lines (unipolar systems) or line and midpoint (bipolar

systems) for distribution domain . 204

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICITY METERING EQUIPMENT –
GENERAL REQUIREMENTS, TESTS AND TEST CONDITIONS –

Part 31: Product safety requirements and tests

FOREWORD
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