IEC 61558-2-5:2024

IEC 61558-2-5 ®
Edition 3.0 2024-08
EXTENDED VERSION
INTERNATIONAL
STANDARD
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This full version of IEC 61558-2-5:2024 includes the content of the references made to
IEC 61558-1:2017
GROUP ENERGY EFFICIENCY PUBLICATION

Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-5: Particular requirements and tests for transformers for shavers, power
supply units for shavers and shaver supply units
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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IEC 61558-2-5 ®
Edition 3.0 2024-08
EXTENDED VERSION
INTERNATIONAL
STANDARD
colour
inside
This full version of IEC 61558-2-5:2024 includes the content of the references made to
IEC 61558-1:2017
GROUP ENERGY EFFICIENCY PUBLICATION
Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-5: Particular requirements and tests for transformers for shavers, power
supply units for shavers and shaver supply units
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.180 ISBN 978-2-8322-9558-8

– 2 – IEC 61558-2-5:2024 EXV © IEC 2024
CONTENTS
FOREWORD . 9
INTRODUCTION to IEC 61558-1:2017 . 12
INTRODUCTION to IEC 61558-2-5:2024 . 15
1 Scope . 16
2 Normative references . 17
3 Terms and definitions . 20
3.1 Transformers . 21
3.2 General terms . 24
3.3 Operations and protections . 26
3.4 Circuits and windings . 27
3.5 Ratings . 28
3.6 No-load values . 30
3.7 Insulation . 30
3.8 Touch current and protective earthing conductor current . 34
4 General requirements . 34
5 General notes on tests . 35
6 Ratings . 37
7 Classification . 38
8 Marking and other information . 39
9 Protection against electric shock . 45
9.1 General . 45
9.2 Protection against contact with hazardous-live-parts . 45
9.2.1 Determination of hazardous-live-parts . 45
9.2.2 Accessibility to hazardous-live-parts . 46
9.2.3 Accessibility to non hazardous-live-part . 49
9.3 Protection against hazardous electrical discharge . 49
10 Change of input voltage setting . 49
11 Output voltage and output current under load . 50
12 No-load output voltage . 51
13 Short-circuit voltage . 51
14 Heating . 51
14.1 General requirements . 51
14.1.1 Temperature-rise test . 51
14.1.2 Alternative temperature-rise test . 54
14.1.3 Determination of steady-state conditions . 56
14.2 Application of 14.1 or 14.3 according to the insulation system. 58
14.3 Accelerated ageing test for undeclared class of insulation system . 58
14.3.1 General . 58
14.3.2 Heat run . 59
14.3.3 Vibration . 59
14.3.4 Moisture treatment . 59
14.3.5 Measurements . 59
15 Short circuit and overload protection. 60
15.1 General requirements . 60
15.1.1 Short circuit and overload test method . 60

15.1.2 Alternative short circuit and overload test method . 62
15.2 Inherently short-circuit proof transformers . 62
15.3 Non-inherently short-circuit proof transformers. 62
15.4 Non-short-circuit proof transformers . 63
15.5 Fail-safe transformers . 63
16 Mechanical strength . 64
16.1 General . 64
16.2 Stationary transformers . 65
16.3 Portable transformers (except portable transformers with integral pins for
introduction in socket-outlet in the fixed wiring) . 66
16.4 Portable transformers provided with integral pins for introduction in socket-
outlets of the fixed wiring . 66
16.4.1 General requirements . 66
16.4.2 Portable transformers provided with integral pins according to EN
50075 (IEC plug type C) for introduction in socket-outlets of the fixed
wiring . 67
16.5 Additional requirements for transformers to be used in vehicles and railway
applications . 68
16.5.1 Transformers to be used in vehicles and railway applications . 68
16.5.2 Test requirements for the transportation of transformers . 69
17 Protection against harmful ingress of dust, solid objects and moisture . 70
17.1 Degrees of protection provided by enclosures (IP code) . 70
17.1.1 General requirements . 70
17.1.2 Tests on transformers with enclosure . 71
17.2 Humidity treatment . 73
18 Insulation resistance, dielectric strength and leakage current . 74
18.1 General . 74
18.2 Insulation resistance . 74
18.3 Dielectric strength test . 74
18.4 Insulation between and within windings . 76
18.5 Touch current and protective earthing conductor current . 76
18.5.1 General . 76
18.5.2 Touch current . 77
18.5.3 Protective earthing conductor current . 78
19 Construction . 78
19.1 General construction . 78
19.2 Flammability of materials . 80
19.3 Short-circuit characteristics of portable transformers . 80
19.4 Class II transformer contact prevention of accessible conductive parts . 80
19.5 Class II transformer insulation reassembling after service . 80
19.6 Loosening of wires, screws or similar parts . 80
19.7 Resistor or capacitor connection with accessible conductive parts . 81
19.8 Bridging of separated conductive parts by resistors or capacitors . 81
19.9 Insulating material separating input and output windings . 82
19.10 Accidental contact protection against hazardous-live-parts provided by
isolating coating . 82
19.11 Insulating material of handles, operating levers, knobs and similar parts. 83
19.12 Winding construction . 83
19.13 Fixing of handles, operating levers and similar parts . 87
19.14 Fixing of covers providing protection against electric shock . 87

– 4 – IEC 61558-2-5:2024 EXV © IEC 2024
19.15 Strain on fixed socket-outlets caused by pin-transformers connection . 88
19.16 Portable transformers for use in irregular or harsh conditions . 88
19.17 Drain hole of transformers protected against ingress of water . 88
19.18 Plug connected transformers protected against ingress of water . 88
19.19 Flexible cable or flexible cord connection for class I portable transformers . 88
19.20 SELV- and PELV-circuit separation of live parts . 88
19.21 Protection against contact for FELV-circuit. 89
19.22 Protective earthing regarding class II transformers . 89
19.23 Protective earthing regarding class III transformers . 89
20 Components . 90
21 Internal wiring . 96
22 Supply connection and other external flexible cables or cords . 96
23 Terminals for external conductors . 103
24 Provisions for protective earthing. 104
25 Screws and connections . 106
26 Creepage distances, clearances and distances through insulation . 108
26.1 General . 108
26.2 Creepage distances and clearances . 109
26.2.1 General . 109
26.2.2 Windings covered with adhesive tape . 109
26.2.3 Uncemented insulationing parts . 109
26.2.4 Cemented insulating parts . 109
26.2.5 Enclosed parts (e.g. by impregnation or potting) . 110
26.3 Distance through insulation . 111
27 Resistance to heat, fire and tracking . 122
27.1 General . 122
27.2 Resistance to heat . 122
27.2.1 General . 122
27.2.2 External accessible parts . 122
27.2.3 Internal parts . 123
27.3 Resistance to abnormal heat under fault conditions . 123
27.4 Resistance to fire . 124
27.4.1 General . 124
27.4.2 External accessible parts . 125
27.4.3 Internal parts . 125
27.5 Resistance to tracking . 126
28 Resistance to rusting . 126
Annex A (normative) Measurement of creepage distances and clearances. 127
Annex B (normative) Testing a series of transformers . 131
B.1 General . 131
B.2 Requirements . 131
B.3 Constructional inspection . 132
Annex C (void) . 133
Annex D (void) . 134
Annex E (normative) Glow-wire test . 135
E.1 General . 135
E.2 Severity . 135

E.3 Conditioning . 135
E.4 Test procedure . 135
Annex F (normative) Requirements for manually operated switches which are parts of
transformers assembly . 136
F.1 General . 136
F.2 Switches tested as a separate component . 136
F.3 Switches tested as part of the transformer . 136
Annex G (normative) Tracking test . 139
G.1 General . 139
G.2 Test specimen . 139
G.3 Test apparatus . 139
G.4 Procedure . 139
Annex H (normative) Electronic circuits . 140
H.1 General . 140
H.2 General notes on tests (addition to Clause 5). 140
H.3 Short circuit and overload protection (addition to Clause 15) . 140
H.4 Creepage distances, clearances and distances through insulation (addition
to Clause 26) . 142
Annex I (informative) Dimensions for rectangular cross-section connectors of
transformers, basic dimensions and coordination . 144
Annex J (normative) Measuring network for touch-currents . 146
Annex K (normative) Insulated winding wires . 147
K.1 General . 147
K.2 Type tests . 147
K.2.1 General . 147
K.2.2 Dielectric strength test . 147
K.2.3 Flexibility and adherence . 147
K.2.4 Heat shock . 148
K.2.5 Retention of dielectric strength after bending . 148
K.3 Testing during manufacturing . 149
K.3.1 General . 149
K.3.2 Routine test . 149
K.3.3 Sampling test . 149
Annex L (normative) Routine tests (production tests) . 150
L.1 General . 150
L.2 Protective earthing continuity test . 150
L.3 Checking of no-load output voltage . 150
L.4 Dielectric strength test . 150
L.5 Checking of protective devices mounting . 151
L.6 Visual inspection . 151
L.7 Repetition test after routine dielectric strength test . 151
Annex M (informative) Examples to be used as a guide for 19.1 . 152
M.1 General . 152
M.2 Coil-former . 152
M.2.1 Concentric type . 152
M.2.2 Side-by-side type . 153
M.3 Windings . 153
M.3.1 Without screen . 153

– 6 – IEC 61558-2-5:2024 EXV © IEC 2024
M.3.2 With screen . 154
Annex N (informative) Examples for checking points of dielectric strength test voltages . 155
Annex O (void) . 157
Annex P (informative) Examples for measurement points of creepage distances and
clearances . 158
Annex Q (informative) Explanation of IP numbers for degrees of protection . 161
Q.1 General . 161
Q.2 Degrees of protection against access to hazardous parts and against solid
foreign objects . 161
Q.3 Degrees of protection against ingress of water . 163
Annex R (normative) Explanations of the application of 6.1.2.2.1 of IEC 60664-1:2007 . 164
R.1 Impulse dielectric test . 164
R.2 Example. 164
Annex S (void) . 166
Annex T (void) . 167
Annex U (void) . 168
Annex V (informative) Symbols to be used for thermal cut-outs . 169
V.1 General . 169
V.2 Non-self-resetting thermal cut-out (see 3.3.4) . 169
V.3 Self-resetting thermal cut-out (see 3.3.3) . 169
Annex W (normative) Coated printed circuit boards . 170
W.1 Preamble . 170
W.2 General . 170
W.3 Cold . 170
W.4 Rapid change of temperature . 170
W.5 Additional tests . 170
Bibliography . 171
Index of defined terms . 173

Figure 1 – IEC 61558 principle . 13
Figure 2 – Mounting box for flush-type transformer . 37
Figure 3 – Test pin (see IEC 61032, test probe 13) . 47
Figure 4 – Standard test finger (see IEC 61032, test probe B) . 48
Figure 5 – Example of back-to-back method – Single phase . 55
Figure 6 – Example of back-to-back method – Three phase . 56
Figure 7 – Amplitude spectrum density for random testing . 68
Figure 8 – Normalised spectrum of shock . 69
Figure 9 – Test voltage sequence . 76
Figure 10 – Test configuration: single-phase equipment on star TN or TT system . 78
Figure 11 – Abrasion resistance test for insulating coated layers . 83
Figure 12 – Flexing test apparatus . 100
Figure 13 – Test arrangement for checking mechanical withstanding of insulating
materials in thin sheet layers . 114
Figure 14 – Ball-pressure apparatus . 122
Figure A.1 – Example 1. 127
Figure A.2 – Example 2. 128

Figure A.3 – Example 3. 128
Figure A.4 – Example 4. 128
Figure A.5 – Example 5. 129
Figure A.6 – Example 6. 129
Figure A.7 – Example 7. 130
Figure A.8 – Example 8. 130
Figure H.1 – Example of an electronic circuit with low-power points . 143
Figure J.1 – Measuring network for touch-current . 146
Figure M.1 – Examples for concentric type constructions . 152
Figure M.2 – Examples for side-by-side type constructions . 153
Figure M.3 – Examples for winding constructions without screen . 153
Figure M.4 – Examples for wrapped winding constructions . 154
Figure M.5 – Examples for winding constructions with screen . 154
Figure N.1 – Transformer of class I construction with metal enclosure . 155
Figure N.2 – Transformer of class II construction with metal enclosure . 156
Figure N.3 – Transformer of class II construction with enclosure of insulating material . 156
Figure P.1 – Transformer of class I construction . 158
Figure P.2 – Transformer of class I construction with earthed metal screen . 159
Figure P.3 – Transformer of class II construction with metal enclosure . 159
Figure P.4 – Transformer of class II construction with enclosure of insulating material . 160
Figure V.1 – Restored by manual operation . 169
Figure V.2 – Restored by disconnection of the supply . 169
Figure V.3 – Thermal link (see 3.3.5) . 169
Figure V.4 – Self-resetting thermal cut-out . 169

Table 1 – Symbols used on equipment or in instructions . 42
Table 101 – Symbols indicating the kind of transformer . 43
Table 2 – Values of maximum temperatures in normal use . 57
Table 3 – Explanation of the maximum winding temperatures required in Table 2 . 58
Table 4 – Test temperature and testing time (in days) per cycle . 59
Table 5 – Maximum values of temperatures under short-circuit or overload conditions . 61
Table 6 – Values of T and k for fuses . 62
Table 102 – Values of heights of fall . 65
Table 7 – Pull force on pins . 67
Table 8 – Conditions for vibration testing (random) . 68
Table 9 – Amplitude spectrum density ASD values for accelerated life testing . 68
Table 10 – Frequency values depending on the weight of the specimen . 69
Table 11 – Excitation values for vibration testing . 69
Table 12 – Solid-object-proof transformer test . 71
Table 13 – Values of insulation resistance . 74
Table 14 – Table of dielectric strength test voltages. 75
Table 15 – Limits for currents . 78
Table 16 – Nominal cross-sectional areas of external flexible cables or cords . 98

– 8 – IEC 61558-2-5:2024 EXV © IEC 2024
Table 17 – Pull and torque to be applied to external flexible cables or cords fixed to
stationary and portable transformers . 102
Table 18 – Torque to be applied to screws and connections . 107
Table 19 – Torque test on glands . 108
Table 20 – Clearances in mm . 115
Table 21 – Creepage distances in mm . 116
Table 22 – Distance through insulation in mm . 117
Table 23 – Creepage distances and clearance between terminals for external
connection . 118
Table 24 – Values of FIW wires with minimum overall diameter and minimum test
voltages according to the total enamel increase . 120
Table A.1 – Width of groove values depending on the pollution degree . 127
Table F.1 – Peak surge current of additional loads. 137
Table I.1 – Dimensions of rectangular copper connectors . 144
Table K.1 – Mandrel diameter . 148
Table K.2 – Oven temperature . 148
Table Q.1 – Degrees of protection against access to hazardous parts indicated by the
first characteristic numeral . 162
Table Q.2 – Degrees of protection against solid foreign objects indicated by the first
characteristic numeral . 162
Table Q.3 – Degrees of protection indicated by the second characteristic numeral . 163
Table R.1 – Impulse test voltage according to 6.1.2.2.1 of IEC 60664-1:2007 . 164

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –
Part 2-5: Particular requirements and tests for transformers for shavers,
power supply units for shavers and shaver supply units
FOREWORD
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This extended version (EXV) of the official IEC Standard provides the user with the
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made to IEC 61558-1:2017.
The specific content of IEC 61558-2-5:2024 is displayed on a blue background.

– 10 – IEC 61558-2-5:2024 EXV © IEC 2024
IEC 61558-2-5 has been prepared by IEC technical committee 96: Transformers, reactors,
power supply units and combinations thereof. It is an International Standard.
This third edition cancels and replaces the second edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) adjustment of structure and references in accordance with IEC 61558-1:2017;
b) new symbol for power supply unit with linearly regulated output voltage.
The text of this International Standard is based on the following documents:
Draft Report on voting
96/599/FDIS 96/600/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,
available at www.iec.ch/members_experts/refdocs. The main document types developed by
IEC are described in greater detail at www.iec.ch/publications.
...

IEC 61558-2-5 ®
Edition 3.0 2024-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP ENERGY EFFICIENCY PUBLICATION
PUBLICATION GROUPÉE SUR L'EFFICACITÉ ÉNERGÉTIQUE
Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-5: Particular requirements and tests for transformers for shavers, power
supply units for shavers and shaver supply units

Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et
combinaisons de ces éléments –
Partie 2-5 : Exigences particulières et essais pour les transformateurs pour
rasoirs, les blocs d'alimentation incorporant un transformateur pour rasoir et les
blocs d'alimentation pour rasoirs
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IEC 61558-2-5 ®
Edition 3.0 2024-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP ENERGY EFFICIENCY PUBLICATION

PUBLICATION GROUPÉE SUR L'EFFICACITÉ ÉNERGÉTIQUE

Safety of transformers, reactors, power supply units and combinations thereof –

Part 2-5: Particular requirements and tests for transformers for shavers, power

supply units for shavers and shaver supply units

Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et

combinaisons de ces éléments –

Partie 2-5 : Exigences particulières et essais pour les transformateurs pour

rasoirs, les blocs d'alimentation incorporant un transformateur pour rasoir et

les blocs d'alimentation pour rasoirs

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.180  ISBN 978-2-8322-9415-4

– 2 – IEC 61558-2-5:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 7
4 General requirements . 8
5 General notes on tests . 8
6 Ratings . 8
7 Classification . 9
8 Marking and other information . 9
9 Protection against electric shock . 10
10 Change of input voltage setting . 10
11 Output voltage and output current under load . 10
12 No-load output voltage . 10
13 Short-circuit voltage . 11
14 Heating . 11
15 Short-circuit and overload protection . 11
16 Mechanical strength . 11
17 Protection against harmful ingress of dust, solid objects and moisture . 12
18 Insulation resistance, dielectric strength and leakage current . 13
19 Construction . 13
20 Components . 15
21 Internal wiring . 15
22 Supply connection and other external flexible cables or cords . 15
23 Terminals for external conductors . 16
24 Provisions for protective earthing. 16
25 Screws and connections . 16
26 Creepage distances, clearances and distances through insulation . 16
27 Resistance to heat, fire and tracking . 16
28 Resistance to rusting . 16
Annexes . 17
Bibliography . 18

Table 101 – Symbols indicating the kind of transformer . 10
Table 102 – Values of heights of fall . 12

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –

Part 2-5: Particular requirements and tests for transformers for shavers,
power supply units for shavers and shaver supply units

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
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61558-2-5 has been prepared by IEC technical committee 96: Transformers, reactors,
power supply units and combinations thereof. It is an International Standard.
This third edition cancels and replaces the second edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) adjustment of structure and references in accordance with IEC 61558-1:2017;
b) new symbol for power supply unit with linearly regulated output voltage.

– 4 – IEC 61558-2-5:2024 © IEC 2024
The text of this International Standard is based on the following documents:
Draft Report on voting
96/599/FDIS 96/600/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
It has the status of a group safety publication in accordance with IEC Guide 104.
This document is to be used in conjunction with IEC 61558-1:2017.
This document supplements or modifies the corresponding clauses in IEC 61558-1:2017, so as
to convert that publication into the IEC standard: Particular requirements and tests for
transformers for shavers, power supply units for shavers and shaver supply units.
A list of all parts in the IEC 61558 series published under the general title Safety of transformers,
reactors, power supply units and combinations thereof, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
Where this document states "addition", "modification" or "replacement", the relevant text of
IEC 61558-1:2017 is to be adopted accordingly.
In this document, the following print types are used:
– requirements proper: in roman type;
– test specifications: in italic type;
– explanatory matter: in smaller roman type.
In the text of this document, the words in bold are defined in Clause 3.
Subclauses, notes, figures and tables additional to those in IEC 61558-1:2017 are numbered
starting from 101; supplementary annexes are entitled AA, BB, etc.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
INTRODUCTION
IEC TC 96 has a group safety function in accordance with IEC Guide 104 for transformers other
than those intended to supply distribution networks, in particular transformers and power supply
units intended to allow the application of protective measures against electric shock as defined
by TC 64, which is about Electrical installations and protection against electric shock, but in
certain cases including the limitation of voltage and horizontal safety function for SELV, in
accordance with IEC 60364-4-41.
The group safety function (GSF) is used because of responsibility for example for safety extra-
low voltage (SELV) in accordance with IEC 61140:2016, 5.2.6 and IEC 60364-4-41:2017,
414.3.1 or control circuits in accordance with IEC 60204-1:2016, 7.2.4.
The group safety function is used for each part of IEC 61558-2 because different standards of
the IEC 61558 series can be combined in one construction but in certain cases with no limitation
of rated output power.
For example an auto-transformer in accordance with IEC 61558-2-13 can be designed with a
separate SELV-circuit in accordance with the particular requirements for IEC 61558-2-6 relating
to the general requirements of IEC 61558-1.

– 6 – IEC 61558-2-5:2024 © IEC 2024
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –

Part 2-5: Particular requirements and tests for transformers for shavers,
power supply units for shavers and shaver supply units

1 Scope
Replacement:
This part of IEC 61558 deals with the safety of shaver transformers, power supply units
incorporating a shaver transformer, and shaver supply units. Shaver transformers
incorporating electronic circuits are also covered by this document.
NOTE 1 Safety includes electrical, thermal and mechanical aspects.
Unless otherwise specified, from here onward, the term transformer covers shaver
transformers and power supply units incorporating shaver transformers and shaver supply
units.
For power supply units (linear) this document is applicable. For switch mode power supply
units IEC 61558-2-16 is applicable together with this document. Where two requirements are
in conflict, the most severe take precedence.
This document is applicable to stationary, single-phase, air-cooled (natural or forced)
independent or associated dry-type transformers. The windings can be encapsulated or non-
encapsulated.
The rated supply voltage does not exceed 250 V AC and the rated supply frequency and the
internal operating frequencies do not exceed 500 Hz.
The rated output is not less than 20 VA and does not exceed 50 VA.
The no-load output voltage does not exceed 275 V AC and the rated output voltage does
not exceed 250 V AC.
This document is not applicable to external circuits and their components intended to be
connected to the input and output terminals or socket-outlets of the transformers.
NOTE 2 Transformers covered by this document are only used in applications where double or reinforced
insulation between circuits is specified by the installation rules for bathrooms and similar locations, or by the
appliance specifications.
NOTE 3 Transformers covered by this document can be flush or surface mounted or incorporated in luminaires,
mirrors, and other equipment containing one or more socket-outlet(s).
Attention is drawn to the following, if applicable:
– for transformers intended to be used in vehicles, on board ships, and aircraft, additional
requirements (from other applicable standards, national rules, etc.);
– measures to protect the enclosure and the components inside the enclosure against
external influences such as fungus, vermin, termites, solar-radiation, and icing;
– the different conditions for transportation, storage, and operation of the transformers;

– additional requirements in accordance with other appropriate standards and national rules
can be applicable to transformers intended for use in special environments.
Future technological development of transformers can necessitate a need to increase the
upper limit of the frequencies. Until then this document can be used as a guidance document.
This group safety publication focusing on safety guidance is primarily intended to be used as a
product safety standard for the products mentioned in the scope but is also intended to be used
by technical committees in the preparation of publications for products similar to those
mentioned in the scope of this group safety publication, in accordance with the principles laid
down in IEC Guide 104 and lSO/lEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of
basic safety publications and/or group safety publications in the preparation of its publications.
2 Normative references
This clause of IEC 61558-1:2017 is applicable except as follows:
Addition:
IEC 60068-2-62:1991, Environmental testing – Part 2: Test methods – Test Ef: Impact,
pendulum hammer
IEC TR 60083, Plugs and socket-outlets for domestic and similar general use standardized in
member countries of IEC
IEC 60670 (all parts), Boxes and enclosures for electrical accessories for household and similar
fixed electrical installations
IEC 61558-1:2017, Safety of transformers, reactors, power supply units and combinations
thereof – Part 1: General requirements and tests
IEC 61558-2-16, Safety of transformers, reactors, power supply units and combinations thereof
– Part 2-16: Particular requirements and tests for switch mode power supply units and
transformers for switch mode power supply units for general applications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61558-1:2017 apply,
except as follows:
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
___________
This publication was withdrawn and replaced with IEC 60068-2-75 (1997), but for the purposes of this document
IEC 60068-2-62 is cited.
– 8 – IEC 61558-2-5:2024 © IEC 2024
3.1 Transformers
Addition:
3.1.101
shaver transformer
isolating transformer for fixed installation and with a limited output, designed to supply electric
shavers, toothbrushes, and similar appliances rated 50 VA or less used in a bathroom which
supplies only one shaver, or the like, at a time
3.1.102
shaver supply unit
accessory embodying a shaver transformer or a power supply unit incorporating a shaver
transformer, and one or more socket outlets allowing the use of only one plug at a time
4 General requirements
This clause of IEC 61558-1:2017 is applicable.
5 General notes on tests
This clause of IEC 61558-1:2017 is applicable.
6 Ratings
This clause of IEC 61558-1:2017 is applicable except as follows:
Addition:
6.101 The rated output voltage shall not exceed 250 V AC.
For independent transformers, this output voltage limitation applies even when output
windings, not intended for interconnection, are connected in series.
6.102 The rated output shall not be less than 20 VA and shall not exceed 50 VA.
6.103 The rated supply frequency and the internal operating frequencies shall not exceed
500 Hz.
6.104 The rated supply voltage shall not exceed 250 V AC.
Compliance with the requirements of 6.101 to 6.104 is checked by inspection of the marking.

7 Classification
This clause of IEC 61558-1:2017 is applicable except as follows:
7.2
Replacement:
7.2 According to short-circuit characteristic or protection against abnormal use:
– inherently short-circuit proof transformers;
– non-inherently short-circuit proof transformers;
7.8
Replacement:
7.8 According to their transient overvoltage condition:
– overvoltage category II
8 Marking and other information
This clause of IEC 61558-1:2017 is applicable except as follows:
8.1
h)
Replacement:
Replace the content up to the first semi-colon by the following:
relevant graphical symbols shown in Table 101 that indicate the kind of transformer
m)
Modification:
indication of the degree of protection (IP code) for transformers, if higher than IP00;
indication of the degree of protection (IP code) for shaver supply units, if higher than IP21.
8.7
Addition:
For shaver supply units provided with a single-pole switch, the switched pole shall be
connected to the line.
8.11
Addition:
The symbol for linear power supply units shall be used in conjunction with the symbol
indicating the kind of transformer.

– 10 – IEC 61558-2-5:2024 © IEC 2024
Table 101 – Symbols indicating the kind of transformer
Symbol or graphical symbol Explanation or title Identification
Shaver supply units and shaver transformers IEC 60417-5225:2002-10

Power supply unit, linear IEC 60417-6210:2013-10

8.13
Addition:
For shaver supply units, the marking for rated output voltage(s) and for the symbol of 8.11
shall be indicated on the front of the enclosure so as to be visible when the unit is mounted as
in normal use. For shaver supply units intended to provide different output voltages, the
selected output voltage setting shall be clearly discernible.
For transformers, the marking with the symbol of 8.11 shall be provided only if the transformer
is supplied separately.
9 Protection against electric shock
This clause of IEC 61558-1:2017 is applicable.
10 Change of input voltage setting
This clause of IEC 61558-1:2017 is applicable.
11 Output voltage and output current under load
This clause of IEC 61558-1:2017 is applicable.
12 No-load output voltage
This clause of IEC 61558-1:2017 is applicable except as follows:
Addition
12.101 The no-load output voltage shall not exceed 275 V AC.
For independent transformers, this output voltage limitation applies even when output
windings, not intended for interconnection, are connected in series.
12.102 The difference between the no-load output voltage and the output voltage under
load shall not be excessive.
The ratio between the no-load output voltage measured in Clause 12 and the output voltage
under load measured during the test of Clause 11, expressed as a percentage of the latter
voltage, shall not exceed 20 %.
The ratio is determined by Formula (101):
UU−
no-load load
×100 %
( ) (101)
U
load
where
U is the no-load output voltage, expressed in V;
no-load
U is the output voltage under load, expressed in V.
load
Compliance with the requirements of 12.101 and 12.102 is checked by measuring the no-load
output voltage at the ambient temperature when the transformer is connected to the rated
supply voltage at the rated supply frequency.
13 Short-circuit voltage
This clause of IEC 61558-1:2017 is applicable.
14 Heating
This clause of IEC 61558-1:2017 is applicable.
15 Short-circuit and overload protection
This clause of IEC 61558-1:2017 is applicable.
16 Mechanical strength
This clause of IEC 61558-1:2017 is applicable except as follows:
16.1 General
Replacement:
For shaver supply units, compliance is checked by the test of 16.101.
Addition:
16.101 Shaver supply units are subjected to blows by means of a pendulum hammer, defined
in 16.101.1 to 16.101.3.
16.101.1 Blows are applied to the specimen according to IEC 60068-2-62.
For shaver supply units other than flush-type mounted, the specimen is mounted as described
in 4.2 of IEC 60068-2-62:1991.
For flush-type shaver supply units, the specimen is mounted as shown in Figure 3 of
IEC 60068-2-62:1991.
– 12 – IEC 61558-2-5:2024 © IEC 2024
Flush-type equipment which is intended to be installed by means of screws to lugs recessed in
the mounting block; flush-type equipment for claw fixing is fixed directly to the block by means
of the claws.
The specimen is mounted as in normal use such that the point of impact lies in the vertical
plane through the axis of the pivot of the pendulum.
Before applying the blows, mounting screws of bases, covers and the like are tightened with a
torque equal to two thirds of that specified in Table 18 of IEC 61558-1:2017.
The striking element is allowed to fall from a height equal to that shown in Table 102.
Table 102 – Values of heights of fall
Height of fall Approximate energy Relevant parts
cm J
10 ± 0,1 0,2 Cover plates of shaver supply units for flush-type mounting and for
those parts which are recessed to a depth of at least one quarter of
the largest dimension of the recessed part
15 ± 0,1 0,3 Enclosures
25 ± 0,1 0,5 Other parts
16.101.2 The specimens shall be subjected to 10 blows which are evenly distributed over the
sample.
Five blows shall be applied as follows:
– for shaver supply units intended to be flush mounted, one blow in the centre, one at each
extremity of the area over the recess in the block, and the other two approximately midway
between the previous blows, the specimen being moved horizontally;
– for shaver supply units not intended for flush-type mounting, one blow in the centre, one
on each side of the specimen after it has been turned as far as possible, but not through
more than 60° about a vertical axis, and the other two approximately midway between the
previous blows.
The remaining blows are then applied in the same way after the specimen has been turned
around through 90° of its axis perpendicular to the plywood.
If cable entries are provided, the specimen shall be mounted such that the two lines of the blows
are as far as possible and equidistant from these entries.
16.101.3 After the test, the specimen shall show no damage within the meaning of this
document. In particular, live parts shall not become accessible.
NOTE 1 Damage to the finish, small dents which do not reduce creepage distances or clearances below the
values specified in Clause 26, and small chips which do not adversely affect the protection against electric shock or
moisture are disregarded.
NOTE 2 Cracks not visible with normal vision or corrected vision without magnification and surface cracks in fibre
reinforced mouldings and the like are disregarded.
17 Protection against harmful ingress of dust, solid objects and moisture
This clause of IEC 61558-1:2017 is applicable.

18 Insulation resistance, dielectric strength and leakage current
This clause of IEC 61558-1:2017 is applicable.
19 Construction
This clause of IEC 61558-1:2017 is applicable except as follows:
19.1 General construction
Replacement:
The input and output circuits shall be electrically separated from each other, and the
construction shall be such that there is no possibility of any connection between these circuits,
either directly or indirectly, through other conductive parts, except by deliberate action.
Compliance is checked by inspection and measurements, taking Clause 18 and Clause 26 into
consideration.
19.1.1 The insulation between input and output winding(s) shall consist of double or
reinforced insulation (rated for the working voltage).
In addition, the following applies:
– for class I transformers not intended for connection to the mains supply by means of a
plug, the insulation between the input windings and the body connected to protective
earthing shall consist of at least basic insulation rated for the input voltage. The insulation
between the output windings and the body connected to protective earthing, shall consist
of at least basic insulation (rated for the output voltage);
– for class I transformers intended for connection to the mains supply by means of a plug,
the insulation between the input windings and the body shall consist of at least basic
insulation, and the insulation between the output windings and the body shall consist of
at least supplementary insulation (both basic and supplementary insulations rated for
the working voltage);
– for class II transformers, the insulation between the input windings and the body shall
consist of double or reinforced insulation (rated for the input voltage). The insulation
between the output windings and the body shall consist of double or reinforced
insulation (rated for the output voltage).
19.1.2 For transformers with intermediate conductive parts (e.g. the iron core) not
connected to the body and located between the input and output windings the insulation
between the input windings and any intermediate conductive part shall consist of at least
basic insulation, and the insulation between the output windings and any intermediate
conductive part shall consist of at least supplementary insulation (both basic and
supplementary insulations rated for the working voltage).
NOTE 1 An intermediate conductive part not separated from the input or output windings or the body by at
least basic insulation is considered to be connected to the relevant part(s).
NOTE 2 Basic insulation and supplementary insulation are interchangeable.
In addition, the following applies:
– for class I transformers, the insulation between the input and output windings via the
intermediate conductive parts (even if they are connected to protective earthing) shall
consist of double or reinforced insulation (rated for the working voltage);

– 14 – IEC 61558-2-5:2024 © IEC 2024
– for class II transformers, the insulation between the input windings and the body and
between the output windings and the body via the intermediate conductive parts shall
consist of double or reinforced insulation (rated for the input and output voltage);
– for transformers different from independent (IP00), the insulation between the input and
output windings via the intermediate conductive parts shall consist of double or
reinforced insulation (rated for the working voltage).
NOTE 3 In 19.1.2 the possibility to consider the intermediate metal part connected to protective earthing and
consequently to require basic insulation in both circuits (primary and secondary) is not allowed for the following
reason:
– the intermediate metal part is normally the iron core made by laminated plates insulated to each other by oxide.
It is not assured that all foils are correctly connected to the protective earthing.
– for transformers different from independent, it is not assured that in the final applications the iron core will be
connected to protective earthing.
Addition:
19.101 There shall be no connections between the output circuit and the protective earthing.
19.102 There shall be no connections between the output circuit and the body.
Compliance is checked by inspection.
19.103 These input and output terminals for the connection of external wiring shall be so
located that the distance measured between the points of introduction of the conductors into
these terminals is not less than 25 mm. If a barrier is used to obtain this distance, the
measurement shall be made over and around the barrier which shall be of insulating material
and permanently fixed to the transformer.
Compliance is checked by inspection and by measurement disregarding intermediate
conductive parts.
19.104 Mounting boxes for transformers or shaver supply units for flush-type mounting shall
comply with IEC 60670 series.
Compliance is checked by inspection.
19.105 Shaver supply units shall be provided with socket-outlets in the output circuit. It
shall not be possible to insert more than one plug at the same time. It shall not be possible for
any of the plugs listed in 20.5 to be inserted so as to bridge two socket outlets.
Compliance is checked by inspection and by manual test.
19.106 Transformers and shaver supply units shall be inherently or non-inherently short-
circuit proof and they shall not incorporate fuses.
Compliance is checked by inspection.

20 Components
This clause of IEC 61558-1:2017 is applicable except as follows:
20.5
Modification:
Shaver supply units can be provided with a changeover switch to provide different rated
output voltages and/or a single-pole switch in the input circuit; these switches can be of
micro-gap construction.
Compliance is checked by inspection.
20.6
Modification:
Socket outlets in the output circuits of shaver supply units shall accept one or more type of
plugs in accordance with IEC TR 60083 and shall not have a protective earthing contact.
NOTE It is not necessary to check the socket outlet according to IEC 60884-1 as:
– constructional, mechanical and material characteristics are already covered by the existing clauses of
IEC 61558-1:2017;
– electrical tests (temperature rise, breaking capacity, normal operation) are not applicable as the socket outlet is
supplied by a transformer with limited power;
– for the protection against electric shock the requirements of this document are considered sufficient as the socket
outlet is supplied by isolating transformer.
20.10
Replacement:
Transformers can be provided with self-resetting protective devices.
21 Internal wiring
This clause of IEC 61558-1:2017 is applicable.
22 Supply connection and other external flexible cables or cords
This clause of IEC 61558-1:2017 is applicable except as follows:
22.2
Addition:
Shaver supply units shall be provided with or be designed for use with a mounting box. They
shall be designed such that the supply cable ends can be prepared for connection after the box
is mounted in position but before the unit is fitted into the box.

– 16 – IEC 61558-2-5:2024 © IEC 2024
Shaver supply units shall be designed and constructed so as to permit easy introduction of
the supply conductors into the terminals and provide adequate space within the box such that
after installation of the unit, the insulation of the supply conductors is unlikely to come into
contact with live parts of different polarity or with moving parts such as the spindle of a rotary
switch.
23 Terminals for external conductors
This clause of IEC 61558-1:2017 is applicable.
24 Provisions for protective earthing
This clause of IEC 61558-1:2017 is applicable.
25 Screws and connections
This clause of IEC 61558-1:2017 is applicable.
26 Creepage distances, clearances and distances through insulation
This clause of IEC 61558-1:2017 is applicable.
27 Resistance to heat, fire and tracking
This clause of IEC 61558-1:2017 is applicable.
28 Resistance to rusting
This clause of IEC 61558-1:2017 is applicable.

Annexes
The annexes of IEC 61558-1:2017 are applicable.

– 18 – IEC 61558-2-5:2024 © IEC 2024
Bibliography
The bibliography of IEC 61558-1:2017 is applicable, except as follows:
Addition:
IEC 60204-1:2016, Safety of machinery - Electrical equipment of machines – Part 1: General
requirements
IEC 60884-1:2022, Plugs and socket-outlets for household and similar purposes – Part 1:
General requirements
IEC 61558 (all parts), Safety of transformers, reactors, power supply units and combinations
thereof
IEC 61558-2-13, Safety of transformers, reactors, power supply units and combinations thereof
– Part 2-13: Particular requirements and tests for auto-transformers and power supply units
incorporating auto-transformers for general applications
ISO/IEC Guide 51:2014, Safety aspects – Guidelines for their inclusion in standards

___________
– 20 – IEC 61558-2-5:2024 © IEC 2024
SOMMAIRE
AVANT-PROPOS . 21
INTRODUCTION . 24
1 Domaine d'application . 25
2 Références normatives . 26
3 Termes et définitions . 27
4 Exigences générales . 27
5 Généralités sur les essais . 27
6 Caractéristiques assignées . 27
7 Classification . 28
8 Marquage et indications. 28
9 Protection contre les chocs électriques . 29
10 Changement de la tension primaire d’alimentation . 29
11 Tension secondaire et courant secondaire en charge . 30
12 Tension secondaire à vide . 30
13 Tension de court-circuit . 30
14 Échauffements . 30
15 Protection contre les courts-circuits et les surcharges . 30
16 Résistance mécanique. 31
17 Pro
...