IEC 61557-16:2023

Electrical safety in low voltage distribution systems up to 1 000 V AC and 1 500 V DC - Equipment for testing, measuring or monitoring of protective measures - Part 16: Equipment for testing the effectiveness of the protective measures of electrical equipment and/or medical electrical equipment

IEC 61557-16:2023 specifies the requirements applicable to the performance for test and measurement equipment in order to determine the effectiveness of the protective measures for electrical equipment and/or medical electrical equipment described in IEC 62353.
This International Standard is to be used in conjunction with IEC 61557-1:2019.
IEC 61557-16:2023 cancels and replaces the first edition published in 2014. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) splitting of uncertainty requirements for medical and non-medical electrical equipment in 4.2.1;
b) addition of a definition of ranges with defined uncertainty in 4.2.1 to 4.2.7;
c) addition of an optional measuring device (MD) for non-medical devices in 4.2.1;
d) addition of a limitation of the maximum intrinsic uncertainty for medical applications at leakage current in 4.2.1;
e) change of 4.2.3 from test sockets to sockets for service purposes;
f) addition of a warning in the operating instructions;
g) integration of former 6.3 into 6.2;
h) update of Table 1;
i) alignment of the structure with that of the whole IEC 61557 series.

Sécurité électrique dans les réseaux de distribution basse tension au plus égale à 1 000 V en courant alternatif et 1 500 V en courant continu - Dispositifs de contrôle, de mesure ou de surveillance de mesures de protection - Partie 16: Équipement pour les essais de bon fonctionnement des mesures de protection des appareils électriques et/ou des appareils électromédicaux

L'IEC 61557-16:2023 spécifie les exigences de performance applicables pour les dispositifs de contrôle et de mesure afin de déterminer le bon fonctionnement des mesures de protection des appareils électriques et/ou des appareils électromédicaux décrits dans l’IEC 62353.
L'IEC 61557-16:2023 annule et remplace la première édition parue en 2014. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
a) séparation des exigences d’incertitude pour les appareils électromédicaux et électriques non médicaux en 4.2.1;
b) ajout d’une définition de plages avec une incertitude définie de 4.2.1 à 4.2.7;
c) ajout d’un dispositif de mesure (DM) facultatif pour les appareils non médicaux en 4.2.1;
d) ajout d’une limitation de l’incertitude intrinsèque maximale pour les applications médicales au niveau du courant de fuite en 4.2.1;
e) changement en 4.2.3 de "prises de courant d’essai" en "prises de courant pour des besoins de service";
f) ajout d’un avertissement dans les instructions de fonctionnement;
g) intégration de l’ancien 6.3 en 6.2;
h) mise à jour du Tableau 1;
i) alignement de la structure sur celle de l’ensemble de la série IEC 61557.

General Information

• Status: Published
• Publication Date: 24-Aug-2023
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 29.080.01 - Electrical insulation in general
• Technical Committee: TC 85 - Measuring equipment for electrical and electromagnetic quantities
• Drafting Committee: WG 8 - TC 85/WG 8
• Current Stage: PPUB - Publication issued
• Start Date: 25-Aug-2023
• Completion Date: 18-Aug-2023

Relations

• Revises: IEC 61557-16:2014 - Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c - Equipment for testing, measuring or monitoring of protective measures - Part 16: Equipment for testing the effectiveness of the protective measures of electrical equipment and/or medical electrical equipment
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61557-16 ®
Edition 2.0 2023-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective
measures –
Part 16: Equipment for testing the effectiveness of the protective measures of
electrical equipment and/or medical electrical equipment

Sécurité électrique dans les réseaux de distribution basse tension au plus égale
à 1 000 V en courant alternatif et 1 500 V en courant continu – Dispositifs de
contrôle, de mesure ou de surveillance de mesures de protection –
Partie 16: Équipement pour les essais de bon fonctionnement des mesures de
protection des appareils électriques et/ou des appareils électromédicaux
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et
les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Secretariat Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: [e-mail].
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC -  IEC Products & Services Portal - products.iec.ch
webstore.iec.ch/advsearchform Découvrez notre puissant moteur de recherche et consultez
La recherche avancée permet de trouver des publications IEC gratuitement tous les aperçus des publications. Avec un
en utilisant différents critères (numéro de référence, texte, abonnement, vous aurez toujours accès à un contenu à jour
comité d’études, …). Elle donne aussi des informations sur les adapté à vos besoins.
projets et les publications remplacées ou retirées.

Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
Le premier dictionnaire d'électrotechnologie en ligne au monde,
Restez informé sur les nouvelles publications IEC. Just
avec plus de 22 300 articles terminologiques en anglais et en
Published détaille les nouvelles publications parues.
français, ainsi que les termes équivalents dans 19 langues
Disponible en ligne et une fois par mois par email.
additionnelles. Egalement appelé Vocabulaire

Electrotechnique International (IEV) en ligne.
Service Clients - webstore.iec.ch/csc

Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
[e-mail].
IEC 61557-16 ®
Edition 2.0 2023-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical safety in low voltage distribution systems up to 1 000 V AC and

1 500 V DC – Equipment for testing, measuring or monitoring of protective

measures –
Part 16: Equipment for testing the effectiveness of the protective measures of

electrical equipment and/or medical electrical equipment

Sécurité électrique dans les réseaux de distribution basse tension au plus

égale à 1 000 V en courant alternatif et 1 500 V en courant continu – Dispositifs

de contrôle, de mesure ou de surveillance de mesures de protection –

Partie 16: Équipement pour les essais de bon fonctionnement des mesures de

protection des appareils électriques et/ou des appareils électromédicaux

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20, 29.080.01 ISBN 978-2-8322-7251-0

– 2 – IEC 61557-16:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Requirements . 9
4.1 General requirements . 9
4.2 Measuring functions . 9
4.2.1 Minimum measuring function requirements . 9
4.2.2 Measurement of the resistance of the protective bonding or the
protective earth resistance . 10
4.2.3 Measurement of insulation resistance . 10
4.2.4 Measurement of protective conductor current or equipment leakage
current with the alternative method . 11
4.2.5 Measurement of touch current, patient leakage current and applied part
leakage current with the alternative method . 11
4.2.6 Measurement of protective conductor current and equipment leakage
current with the direct or differential (residual) method . 12
4.2.7 Measurement of touch current, patient leakage current and applied part
leakage current with the direct or differential (residual) method . 13
4.3 Construction requirements . 13
4.3.1 Overvoltage capability . 13
4.3.2 Terminals . 13
4.3.3 Sockets for service purpose . 14
4.3.4 Degree of protection . 14
4.3.5 Class of protection . 14
4.3.6 Overvoltage and measurement categories . 14
4.3.7 Accessories . 14
5 Markings and operating instructions . 15
5.1 Markings . 15
5.2 Operating instructions . 15
6 Tests . 15
6.1 General . 15
6.2 Operating uncertainty . 15
6.3 Tests of measuring circuits according to measuring functions . 18
6.4 Test of construction requirements of test and measurement equipment . 18
Annex A (normative) Measuring circuit MD . 19
A.1 Current measuring circuit MD . 19
A.2 Frequency characteristic of current measuring circuit MD . 20
Bibliography . 21

Figure A.1 – Current measuring circuit MD . 19
Figure A.2 – Frequency characteristic of the current measuring circuit MD . 20

Table 1 – Calculation of operating uncertainty for leakage measurements with direct or
differential method . 17
Table 2 – Compliance tests of measuring circuits according to measuring function . 18
Table 3 – Compliance test of construction requirements of test and measuring
equipment . 18

– 4 – IEC 61557-16:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL SAFETY IN LOW VOLTAGE DISTRIBUTION SYSTEMS
UP TO 1 000 V AC AND 1 500 V DC – EQUIPMENT FOR TESTING,
MEASURING OR MONITORING OF PROTECTIVE MEASURES –

Part 16: Equipment for testing the effectiveness of the protective
measures of electrical equipment and/or medical electrical equipment

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) 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.
IEC 61557-16 has been prepared by IEC technical committee 85: Measuring equipment for
electrical and electromagnetic quantities. It is an International Standard.
This second edition cancels and replaces the first edition published in 2014. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) splitting of uncertainty requirements for medical and non-medical electrical equipment in
4.2.1;
b) addition of a definition of ranges with defined uncertainty in 4.2.1 to 4.2.7;
c) addition of an optional measuring device (MD) for non-medical devices in 4.2.1;

d) addition of a limitation of the maximum intrinsic uncertainty for medical applications at
leakage current in 4.2.1;
e) change of 4.2.3 from test sockets to sockets for service purposes;
f) addition of a warning in the operating instructions;
g) integration of former 6.3 into 6.2;
h) update of Table 1;
i) alignment of the structure with that of the whole IEC 61557 series.
The text of this International Standard is based on the following documents:
Draft Report on voting
85/876/FDIS 85/885/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.
This International Standard is to be used in conjunction with IEC 61557-1:2019.
A list of all parts in the IEC 61557 series, published under the general title Electrical safety in
low voltage distribution systems up to 1 000 V AC and 1 500 V DC – Equipment for testing,
measuring or monitoring of protective measures, can be found on the IEC website.
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,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61557-16:2023 © IEC 2023
INTRODUCTION
This part of IEC 61557 defines performance requirements of measuring equipment intended for
testing the effectiveness of the protective measures of either electrical equipment or medical
electrical equipment, or both (in accordance with IEC 62353). It is the intention of this document
to achieve comparable measuring results, additional safety for the person carrying out the
testing, and non-damaging electrical stress for the unit under test.

ELECTRICAL SAFETY IN LOW VOLTAGE DISTRIBUTION SYSTEMS
UP TO 1 000 V AC AND 1 500 V DC – EQUIPMENT FOR TESTING,
MEASURING OR MONITORING OF PROTECTIVE MEASURES –

Part 16: Equipment for testing the effectiveness of the protective
measures of electrical equipment and/or medical electrical equipment

1 Scope
This part of IEC 61557 specifies the requirements applicable to the performance for test and
measurement equipment in order to determine the effectiveness of the protective measures for
electrical equipment and/or medical electrical equipment described in IEC 62353.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic safety
and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 60601-1:2005/AMD2:2020
IEC 61010-1:2010, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 1: General requirements
IEC 61010-1:2010/AMD1:2016
IEC 61010-031, Safety requirements for electrical equipment for measurement, control and
laboratory use – Part 031: Safety requirements for hand-held and hand-manipulated probe
assemblies for electrical test and measurement
IEC 61010-2-030, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 2-030: Particular requirements for equipment having testing or measuring
circuits
IEC 61010-2-032, Safety requirements for electrical equipment for measurement, control and
laboratory use – Part 2-032: Particular requirements for hand-held and hand-manipulated
current sensors for electrical test and measurement
IEC 61010-2-034, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 2-034: Particular requirements for measurement equipment for insulation
resistance and test equipment for electric strength
IEC 61557-1:2019, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 1:
General requirements
– 8 – IEC 61557-16:2023 © IEC 2023
IEC 61557-2, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 2:
Insulation resistance
IEC 61557-4, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 4:
Resistance of earth connection and equipotential bonding
IEC 61557-10, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 10:
Combined measuring equipment for testing, measuring or monitoring of protective measures
IEC 61557-13, Electrical safety in low voltage distribution systems up to 1 000 V AC and
1 500 V DC – Equipment for testing, measuring or monitoring of protective measures – Part 13:
Hand-held and hand-manipulated current clamps and sensors for measurement of leakage
currents in electrical distribution systems
IEC 62353:2014, Medical electrical equipment – Recurrent test and test after repair of medical
electrical equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61557-1, IEC 61557-2,
IEC 61557-4, IEC 61557-10 and IEC 61557-13, and the following apply.
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
3.1
test socket outlet
socket outlet on the test equipment that can be switched to either test-condition or supply
condition
3.2
service socket
socket outlet on the test equipment to supply mains to further test equipment or additional
equipment
3.3
measuring circuit MD
electric circuit with defined components and defined frequency characteristic
3.4
peak factor
ratio of the maximum absolute value of an alternating quantity to its RMS value
[SOURCE: IEC 60050-103:2017, 103-06-15, modified – Note to entry omitted.]
3.5
medical electrical equipment
ME equipment
electrical equipment having an applied part or transferring energy to or from the patient or
detecting such energy transfer to or from the patient and which is:

a) provided with not more than one connection to a particular supply mains, and
b) intended by its manufacturer to be used:
– in the diagnosis, treatment, or monitoring of a patient, or
– for compensation or alleviation of disease, injury or disability
Note 1 to entry: ME equipment includes those accessories as defined by the manufacturer that are necessary to
enable the normal use of the ME equipment.
Note 2 to entry: Not all electrical equipment used in medical practice falls within this definition (e.g. some in vitro
diagnostic equipment).
Note 3 to entry: The implantable parts of active implantable medical devices can fall within this definition, but they
are excluded from the scope of IEC 60601-1 by appropriate wording in IEC 60601-1:2005, Clause 1,
IEC 60601-1:2005/AMD1:2012, Clause 1, and IEC 60601-1:2005/AMD2:2020, Clause 1.
[SOURCE: IEC 60601-1:2005, 3.63, modified – Notes 4 and 5 deleted.]
3.6
protective earth resistance
resistance between any accessible conductive part which has to be connected for safety
purposes to the protective earth terminal and the
– protective connector of the mains plug, or
– protective connector of the appliance inlet, or
– protective conductor permanently connected to the supply mains;
resistance between protective connectors at each end of a detachable power supply cord
[SOURCE: IEC 62353:2014, 3.34]
4 Requirements
4.1 General requirements
In addition to the requirements of IEC 61557-1:2019, Clause 4, the following requirements shall
apply.
The requirements of IEC 62353:2014, Annex C shall apply for measuring equipment intended
for medical electrical equipment testing.
Equipment intended for making measurements on electrical equipment shall be rated for
minimum measurement category II in accordance with IEC 61010-2-030.
Insulation measurement equipment shall fulfil the safety requirements of IEC 61010-2-034.
Test leads and test probes used with the measuring equipment shall fulfil the requirements of
IEC 61010-031.
4.2 Measuring functions
4.2.1 Minimum measuring function requirements
The measuring equipment shall be capable of measuring the following quantities as a minimum:
– resistance of protective bonding and/or protective earth resistance,
– insulation resistance,
– protective conductor current and/or equipment leakage current,
– touch current,
– 10 – IEC 61557-16:2023 © IEC 2023
– applied part leakage current for measuring equipment intended for medical electrical
equipment testing (IEC 62353).
The operating uncertainty for all measured parameters within the required ranges at the
applicable limits according to IEC 62353 shall be ±15 % at the maximum. For measurement of
protective conductor current, equipment leakage current, touch current and applied part leakage
current the operating uncertainty shall be determined at a frequency of 50/60 Hz. The frequency
characteristic for higher frequency ranges is given by the MD circuit according to Figure A.1
and Figure A.2.
Leakage currents for medical electrical equipment shall be measured using a measuring circuit
MD with the characteristics defined in Clause A.1 and Clause A.2. Leakage currents for
non-medical electrical equipment may be tested using a measuring circuit MD in accordance
with IEC 61010-1:2010, Clause A.1.
For medical electrical equipment, the maximum intrinsic uncertainty for leakage current
measurements shall be ±5 %.
NOTE If the measuring equipment evaluates a limit, for example 3,5 mA, the maximum applicable uncertainty can
be taken into account, for example ± 15 %. This means that only measurements less than or equal to 2,97 mA can
pass the test.
The operating uncertainty shall be determined in accordance with IEC 61557-1 with the
influence quantities E , E , E , E modified, E , E , and, if applicable, E , E , E in
1 2 3 9 11 12 13 14 15
accordance with IEC 61557-13.
4.2.2 Measurement of the resistance of the protective bonding or the protective earth
resistance
The measuring equipment shall be in accordance with IEC 61557-4. The withstand capability
against extraneous voltages is not required if the test and measurement equipment is not
intended to be used on fixed installed or permanently connected equipment.
To prevent damage to the equipment under test it is recommended to select a test current not
exceeding 1 A.
The measuring circuit shall be separated from the active parts of mains by double or reinforced
insulation in accordance with IEC 61010-1. The protective conductor may be connected to the
measuring circuit, but parallel earth connections shall be indicated and/or taken into account
by the test and measurement equipment.
When external resistances are included in the calibration as a zero offset, this shall be indicated.
The indication shall continue as long as the calibration is valid.
The measuring range shall include the values between 0,05 Ω and 1,99 Ω and the display shall
have a minimum resolution of 0,01 Ω. Within the range of 0,1 Ω and 1,99 Ω, the measuring
current shall not be less than 0,2 A and the operating uncertainty shall be within the limits of
4.2.1.
Continuous measurements shall be possible for measuring currents below 5 A. For higher test
currents, limiting the test duration is allowed.
4.2.3 Measurement of insulation resistance
The measuring equipment shall be in accordance with IEC 61557-2. The withstand capability
against extraneous voltages is not required if the test and measurement equipment is not
intended to test fixed installed or permanently connected equipment.

The measuring range shall include the values between 100 kΩ and 100 MΩ and the display
shall have a minimum resolution of 0,1 MΩ. The operating uncertainty shall be within the limits
of 4.2.1. If the test and measurement equipment is not intended to test applied parts type F in
accordance with IEC 62353, the measuring range can be limited to 10 MΩ.
The measuring circuit shall be separated from the active parts of mains by double or reinforced
insulation in accordance with IEC 61010-1. The protective conductor may be connected to the
measuring circuit.
4.2.4 Measurement of protective conductor current or equipment leakage current
with the alternative method
The alternative method shows values of the leakage current calculated using the test voltage
generated by the measuring equipment.
If the test and measurement equipment include the alternative method, the requirements for the
measuring circuit (in the following dashed list) shall apply:
– sinusoidal test voltage at mains frequency, total harmonic distortion (THD) shall not exceed
5 %;
– open circuit test voltage between 25 V and 250 V. If test and measurement equipment is
specified in accordance with IEC 62353 the test voltage shall be equal to the nominal mains
supply voltage;
– minimum resolution 0,01 mA;
– measuring resistance of up to 1 kΩ (up to 2 kΩ if it is intended for the testing of non-medical
electrical equipment only);
– output current limited to 3,5 mA for test voltages above 50 V;
– scaling of the measured results up to the nominal mains voltage;
– minimum current measuring range between 0,02 mA and 19,99 mA.
If the test and measurement equipment is intended for tests on non-medical electrical
equipment only, the lower limit of the measuring range may be increased to 0,2 mA and the
resolution decreased to 0,1 mA.
The operating uncertainty or intrinsic uncertainty for the range of 0,02 mA or 0,2 mA up to
19,99 mA shall fulfil the requirements of 4.2.1.
The measuring circuit shall be separated from the active parts of mains by double or reinforced
insulation in accordance with IEC 61010-1. The protective conductor may be connected to the
measuring circuit.
4.2.5 Measurement of touch current, patient leakage current and applied part leakage
current with the alternative method
If the test and measurement equipment include the alternative method, the requirements for the
measuring circuit in the following dashed list shall apply:
– sinusoidal test voltage at mains frequency,
– open circuit test voltage between 25 V and 250 V. If test and measurement equipment is
specified in accordance with IEC 62353 the test voltage shall be equal to the nominal mains
supply voltage,
– minimum resolution 0,001 mA,
– measuring resistance of up to 1 kΩ (up to 2 kΩ if it is intended for the testing of non-medical
electrical equipment only),
– output current limitation to 3,5 mA for test voltages above 50 V,
– scaling of the measured results up to the nominal mains voltage,
– scaled minimum current measuring range between 0,02 mA and 19,99 mA.

– 12 – IEC 61557-16:2023 © IEC 2023
If the test and measurement equipment is intended for tests on non-medical electrical
equipment only, the lower limit of the scaled measuring range may be increased to 0,2 mA and
the resolution decreased to 0,01 mA.
The operating uncertainty or intrinsic uncertainty for the range between 0,02 mA or 0,2 mA and
19,99 mA shall fulfil the requirements of 4.2.1.
The measuring circuit shall be separated from the active parts of mains by double or reinforced
insulation in accordance with IEC 61010-1. The protective conductor may be connected to the
measuring circuit.
4.2.6 Measurement of protective conductor current and equipment leakage current
with the direct or differential (residual) method
If the test and measurement equipment include the direct method or differential method the
requirements in the following dashed list shall apply:
– measurement in both polarities of mains supply voltage in the case of single phase
equipment;
– minimum current measuring range (frequency weighted) for non-medical electrical
equipment between 0,25 mA and 19,99 mA;
– minimum current measuring range (frequency weighted) for medical equipment between
0,01 mA and 9,99 mA;
– current measuring range (non-frequency weighted in accordance with Figure A.2) shall be
specified;
– minimum resolution 0,01 mA;
MD for the direct method;
– current measuring circuit
– measurement of RMS values up to a minimum peak factor of 2 taking into account the
required frequency characteristic, see Annex A. In the case of the differential method, the
lower limit of the frequency range is 40 Hz and the upper limit shall be at least 100 kHz;
– scaling of the measured results up to the nominal mains voltage for medical electrical
equipment.
If the test and measurement equipment is intended for tests on non-medical electrical
equipment only, the lower limit of the measuring range may be increased to 0,1 mA and the
resolution may be decreased to 0,1 mA.
The operating uncertainty or intrinsic uncertainty for the range of 0,02 mA or 0,1 mA up to
19,99 mA shall fulfil the requirements of 4.2.1.
The test and measurement equipment shall provide additional protective means against electric
shock or fire when the units under test are in single fault condition.
NOTE Single fault conditions are PE interrupted, neutral interrupted or mains on applied parts.
In the case of automatic test sequences, the applicable limits for resistance of protective
bonding and/or insultation resistance tests and/or alternative methods shall be met before the
unit under test is connected to the mains voltage.
The test sequence shall be interrupted if the applicable limits are not met.
In the case of non-automatic test sequences, the test and measurement equipment shall display
a warning message or indication before the application of the mains supply to the equipment
under test. If external current clamps are used for measurements, they shall comply with the
requirements of IEC 61557-13 and their operating uncertainty shall be included in the test. The
lower limit of the measuring range may be increased to 1 mA.

In the case of current clamps of class 2 and class 1 and external magnetic fields of 30 A/m and
100 A/m, the overall operating uncertainty may be extended to 20 % (class 2 and 30 A/m) and
30 % (class 1 and 100 A/m). Minimum leakage currents shall be evaluated according to the
frequency characteristic beginning at 40 Hz and up to 10 kHz and a warning shall be added to
the operating instructions in accordance with 5.2.
4.2.7 Measurement of touch current, patient leakage current and applied part leakage
current with the direct or differential (residual) method
If the test and measurement equipment include the direct method or differential method, the
requirements in the following dashed list shall apply:
– measurement in both polarities of mains supply voltage in the case of single phase
equipment;
– minimum current measuring range (frequency weighted) between 0,01 mA and 1,99 mA;
– current measuring range (non-frequency weighted) shall be specified;
– minimum resolution 0,001 mA;
– current measuring circuit MD for the direct method;
– measurement of RMS values up to a minimum peak factor of 2, taking into account the
required frequency characteristic, see Annex A. In the case of the differential method, the
lower limit of the frequency range is 40 Hz and the upper limit shall be at least 100 kHz;
– scaling of the measured results up to the nominal mains voltage for medical electrical
equipment.
If the test and measurement equipment is intended for tests on non-medical electrical
equipment only, the lower limit of the measuring range may be increased to 0,1 mA and the
resolution decreased to 0,01 mA.
The operating uncertainty and intrinsic uncertainty for the range of 0,02 mA or 0,1 mA up to
1,99 mA or 9,99 mA shall fulfil the requirements of 4.2.1.
The test and measurement equipment shall provide additional protective means against electric
shock and fire when the units under test are in single fault condition.
NOTE Single fault conditions are PE interrupted, neutral interrupted or mains on applied parts.
In the case of automatic test sequences, the applicable limits for resistance of protective
bonding and/or insulation resistance tests and/or insulation resistance tests and/or the
alternative method shall be met before the unit under test is connected to the mains voltage.
The test sequence shall be interrupted if the applicable limits are not met.
In the case of non-automatic test sequences, the test and measurement equipment shall display
a warning message or indication before the application of the mains supply to the equipment
under test.
4.3 Construction requirements
4.3.1 Overvoltage capability
The overvoltage capability of test and measurement equipment shall be in accordance with the
requirements of IEC 61557-10 if the test and measurement equipment is intended to test fixed
installed or permanently connected equipment.
4.3.2 Terminals
All terminals shall be designed in such a way that, during connection, it shall not be possible
for an operator to unintentionally touch a hazardous live part.

– 14 – IEC 61557-16:2023 © IEC 2023
4.3.3 Sockets for service purpose
Sockets for the connection of further external equipment shall be clearly marked. Protection
against overcurrent and short-circuits for the mains circuits connected to these sockets shall
be provided by:
a) double insulation between active conductors and active conductors and protective
conductor or
b) overcurrent protective devices.
In the case of solution a), a clear warning shall be given in the documentation not to connect
equipment under test to unprotected outlets.
The inner wiring of the service socket shall be designed according to the maximum nominal
current, but at least for 16 A.
4.3.4 Degree of protection
The degree of protection for the enclosure, except service-sockets and terminals, shall be at
least IP40 in accordance with IEC 60529.
4.3.5 Class of protection
Measuring equipment intended to be hand-held during measurement shall be double insulated
in accordance with IEC 61010-1 and IEC 61010-2-030. Other equipment may be protected by
protective bonding.
4.3.6 Overvoltage and measurement categories
4.3.6.1 Overvoltage category
The supply circuit of the test equipment shall be rated at least for overvoltage CAT II in
accordance with IEC 61010-1.
4.3.6.2 Measurement category
Measuring circuits of the test and measurement equipment shall be rated at least for CAT II in
accordance with IEC 61010-2-030. If the test and measurement equipment is not intended to
test fixed installed or permanently connected equipment, measuring circuits to measure
resistance of protective bonding, insulation resistance or leakage currents with the alternative
method may be classified as secondary circuits in accordance with IEC 61010-2-030. External
current clamps shall be rated for minimum CAT II.
For safety reasons, it is advisable to give a warning that there might be a possible connection
to the unit under power supply.
4.3.7 Accessories
Specified accessories shall be in accordance with the requirements of IEC 61010-031.
Current clamps shall be type A in accordance with the requirements of IEC 61010-2-032.

5 Markings and operating instructions
5.1 Markings
In addition to the markings in accordance with IEC 61557-1:2019, 5.1 and 5.2, as well as
markings in accordance with other relevant parts of the IEC 61557 series, IEC 61010-1, and
IEC 61010-2-030, the information in the following list shall be provided on the measuring
equipment:
– service-socket, if applicable, with maximum rated current,
– test and measurement terminals,
– measuring function,
– instructions for connection.
Markings may be visible on a display.
5.2 Operating instructions
In addition to the information listed in IEC 61557-1:2019, 5.3, and in IEC 61010-2-30, the
information in the following dashed list shall be provided in the operating instructions for the
measuring equipment:
– a warning not to connect to unprotected outlets in which no overcurrent devices are
implemented in mains circuits connected to the test socket or service socket;
– warnings about possible hazards during connection of the unit under test to the mains power
supply;
– operating uncertainty, intrinsic uncertainty, influencing quantities and their effect;
– recommendations about intervals for recalibration;
– a warning not to use external clamps with a reduced frequency range in accordance with
4.2.6 for measuring leakage currents of the unit under test which are able to generate
leakage currents with frequencies above 10 kHz or above the specified frequency range of
the clamp;
– if applicable, a warning not to use the test and measuring equipment on fixed installed or
permanently connected equipment.
6 Tests
6.1 General
In addition to the tests of IEC 61557-1:2019, Clause 6, the tests mentioned in the following
paragraph shall be performed.
Safety of measuring equipment shall be tested in accordance with IEC 61010-1,
IEC 61010-2-030, IEC 61010-2-032 and IEC 61010-031.
All tests shall be carried out under reference conditions, unless otherwise stated.
6.2 Operating uncertainty
The operating uncertainty for measuring functions shall be determined in accordance with
IEC 61557-1:2019, 4.2 and 6.2. Applicable influencing quantities according to Table 1 shall be
considered.
The intrinsic uncertainty A shall be determined for each measured parameter under the following
reference conditions (routine test):
– nominal system voltage,
– 16 – IEC 61557-16:2023 © IEC 2023
– nominal system frequency,
– reference temperature (23 °C ± 2 °C),
– reference position according to manufacturer's specification,
– nominal supply voltage or battery voltage,
– no low-frequency external magnetic field,
– specified load current for the differential method (50 % of the maximum load current or
higher).
The intrinsic uncertainty, A, shall be determined at least at the upper and lower limit of the
measuring range under reference conditions. Digitizing error, non-linearity and traceability shall
be considered. The highest value shall be used for the calculation of the operating uncertainty.
The operating uncertainty shall be calculated in accordance with Table 1.
– The variation E due to position shall be determined i
...