IEC 61557-5:2019

IEC 61557-5 ®
Edition 3.0 2019-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
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 5: Resistance to earth
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IEC 61557-5 ®
Edition 3.0 2019-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
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 5: Resistance to earth
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20; 29.080.01; 29.240.01 ISBN 978-2-8322-7235-0

– 2 – IEC 61557-5:2019 RLV © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Requirements . 7
4.1 General . 7
4.2 Output voltage . 7
4.3 Disturbance voltage . 7
4.4 Permissible resistance of probe and auxiliary earth electrode . 8
4.5 Electrical safety . 8
4.6 Clamps intended to measure earth loop resistances according to
IEC 60364-6:2016, Annex C, Clause C.3 . 8
5 Marking and operating instructions . 9
5.1 Marking . 9
5.2 Operating instructions . 9
6 Tests . 9
6.1 General . 9
6.2 Operating uncertainty . 10
6.3 Electrical safety . 12
Annex A (informative) Recommended test configuration for earth loop clamps . 13
A.1 General . 13
A.2 Test purpose . 13
A.3 Test result. 13
Bibliography . 14

Figure A.1 – Test arrangement . 13

Table 1 – Calculation of operating uncertainty . 11

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 5: Resistance to earth
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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

– 4 – IEC 61557-5:2019 RLV © IEC 2019
International Standard IEC 61557-5 has been prepared by IEC technical committee 85:
Measuring equipment for electrical and electromagnetic quantities.
This third edition cancels and replaces the second edition published in 2007. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) definitions and symbols in Clause 3 modified;
b) subclauses in Clause 4 restructured and aligned with other parts of the series;
c) limits for reduced voltages 25 V RMS or 35 V peak removed from 4.5;
d) requirements for clamps added;
e) marking for rated voltages to earth and measurement category added to Clause 5;
f) warning about absence of hazardous voltage added in Clause 5;
g) the term "percentage operating uncertainty" replaced by "operating uncertainty" in
Clause 6;
h) equation for uncertainty corrected in Table 1;
i) new Annex A on test measurements with loop clamps added.
The text of this International Standard is based on the following documents:
FDIS Report on voting
85/685/FDIS 85/696/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
This International Standard is to be used in conjunction with IEC 61557-1:2019.
A list of all parts of 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 "http://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.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

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 5: Resistance to earth
1 Scope
This part of IEC 61557 specifies the requirements for applicable to measuring equipment for
measuring the resistance to earth using an AC voltage.
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 60364-6:2016, Low voltage electrical installations – Part 6: Verification
IEC 61010-1:20012010, Safety requirements for electrical equipment for measurement,
control, and laboratory use – Part 1: General requirements
IEC 61010-1:2010/AMD1:2016
IEC 61010-2-030:2017, 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 61243-3, Live working – Voltage detectors – Part 3: Two-pole low-voltage type
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
3 Terms and definitions
For the purposes of this document, the terms, definitions and symbols given in IEC 61557-1
and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
—————————
A consolidated version of this publication exists, comprising IEC 61010-1:2010 and
IEC 61010-1:2010/AMD1:2016.
– 6 – IEC 61557-5:2019 RLV © IEC 2019
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
series interference voltage
extraneous voltage superimposed on the measuring voltage
3.2
auxiliary earth electrode
additional earth electrode for a current required for the purpose of measurements
3.4
probe
additional earth electrode used as a probe for sampling potentials during measurements
3.1
resistance to earth
R
A
real part of the impedance to earth
Note 1 to entry: resistance to ground (US).
Note 2 to entry: IEC 60364-6 uses the term "earth resistance", which is considered to be the same.
[SOURCE: IEC 60050-195:1998, 195-01-18, modified – Notes 1 and 2 to entry and a symbol
have been added.]
3.2
disturbance voltage
voltage produced between two points on two separate conductors by an electromagnetic
disturbance, measured under specified conditions and superimposed on the measuring
voltage
[SOURCE: IEC 60050-161:1990, 161-04-01, modified – in alignment with the use in this
document; in addition, the deprecated term "interference voltage" has been deleted.]
3.3
earth electrode
conductive part, which may be embedded in a specific conductive medium, for example
concrete or coke, in electric contact with the Earth
[SOURCE: IEC 60050-195:1998, 195-02-01, modified – The US variant, "ground electrode"
has been omitted.]
3.4
earth electrode terminal
connection point for a probe connected to the earth electrode to be tested and that is used for
the injection of the test current required for the purpose of measurement
Note 1 to entry: In accordance with the requirements of this document, earth electrode terminals are marked "E".
3.5
earth electrode probe terminal
connection point for a probe connected to the earth electrode to be tested and that is used as
a voltage probe either connected direct to or nearest to the earth electrode for sampling
potentials during measurement
Note 1 to entry: In accordance with the requirements of this document, earth electrode probe terminals are
marked "ES".
3.6
auxiliary earth electrode terminal
terminal for connection to an additional temporary earth electrode that is used for injection of
a test current required for the purpose of measurements
Note 1 to entry: In accordance with the requirements of this document, auxiliary earth electrode terminals are
marked "H".
3.7
auxiliary earth electrode resistance
R
H
resistance of an additional earth electrode through which current flows that is required for the
purpose of measurements
3.8
probe electrode terminal
additional temporary earth electrode used as a voltage probe for sampling potentials during
measurements
Note 1 to entry: According to the requirements of this document, probe electrode terminals are marked "S".
3.9
probe electrode resistance
R
S
earth electrode resistance of an additional earth electrode used as a probe for sampling
potentials during measurements
4 Requirements
The following requirements as well as those given in IEC 61557-1 shall apply.
4.1 General
In addition to the requirements of IEC 61557-1:2019, Clause 4, the requirements of Clause 4
of this document shall apply.
4.2 Output voltage
The output voltage present across the terminals E and H shall be an AC voltage without a d.c.
component.
The frequency and the waveform shall be chosen so that electrical interference, particularly
from installations operating with system frequency, will not adversely influence the
measurement result to an excessive degree.
4.2 If the influence of interference voltages from distribution systems as a.c. currents or as
d.c. currents exceeds the requirements of 4.3, this shall be stated by the manufacturer in the
operating instructions.
4.3 The maximum percentage operating uncertainty within the measurement range to be
marked or stated shall not exceed ±30 % with the measured value as fiducial value, as
determined in accordance with Table 1.
4.3 Disturbance voltage
Values of influencing voltages caused by AC or DC currents from distribution systems shall be
stated by the manufacturer in the operating instructions and shall be used for the calculation
in Table 1.
– 8 – IEC 61557-5:2019 RLV © IEC 2019
4.4 Permissible resistance of probe and auxiliary earth electrode
The measuring equipment shall be capable of determining whether the maximum permissible
resistances of the probes and auxiliary earth electrodes are exceeded.
4.5 Electrical safety
No hazardous touch voltages shall appear during the measurements. This can be achieved by
a suitable design of the source for the output voltage by:
– limiting the open-circuit value of the output voltage to an r.m.s. value of 50 V or a peak
value of 70 V;
NOTE The open-circuit voltage during measurements in agricultural plants should not exceed an r.m.s. value
of 25 V or a peak value of 35 V.
– limiting the r.m.s. (peak) value of the short-circuit current to 3,5 mA (5 mA) when the value
of the voltage exceeds 50 V (70 V) or 25 V (35 V).
When no compliance with the above condition exists, then an automatic disconnection of
the measurement process shall operate within a time period permissible according to
Figure 1 of IEC 61010-1.
– limiting the open-circuit value of the output voltage to 50 V AC RMS or 70 V peak;
– or, limiting the short-circuit output current to 3,5 mA AC RMS or 5 mA peak in the event
that the output voltage value could exceed U ;
L
– if the output voltage source does not comply with either of the above requirements,
automatic disconnection of the output voltage source shall operate within a permissible
time period, in accordance with IEC 61010-1:2010/AMD1:2016, Figure 2.
Terminals shall be rated for voltages less than or equal to 50 V or, at the minimum, for a
working voltage equal to the nominal voltage of the distribution system and measurement
category II in accordance with IEC 61010-2-030.
In the event of ratings less than or equal to 50 V, a warning shall be given in the operating
instructions to check the absence of hazardous voltage on the earthing system with a
two-pole low-voltage detector according to IEC 61243-3.
Test leads and accessories in accordance with IEC 61010-031, except for earth spikes/rods,
shall, at the minimum, correspond to the rating of the terminals.
4.6 The user shall not be exposed to a voltage exceeding the permissible touch voltage and
the measuring equipment shall recover within specification, when any plug or socket of the
measuring equipment, intended for connection to the distribution system’s power supply is
connected to 120 % of its nominal voltage. Protective devices shall not be activated.
4.6 Clamps intended to measure earth loop resistances according to
IEC 60364­6:2016, Annex C, Clause C.3
Clamps intended to measure the earth loop resistance in accordance with IEC 60364-6:2016,
Annex C, Clause C.3, whether attached to the instrument or stand alone, shall be specified
according to IEC 61010-2-032 as Type A or Type B.
If specified for Type A, the rating shall, at a minimum, be for measurement category II.
If specified for Type B, the rating shall, at a minimum, be for measurement category II and a
warning shall be given in the operating instructions to check in advance the absence of
hazardous voltages on the earthing system with voltage testers according to IEC 61243-3.

5 Marking and operating instructions
5.1 Marking
In addition to the marking in accordance with IEC 61557-1:2019, 5.1 and 5.2, the following
information shall be provided on the measuring equipment:
– measurement range within which the maximum operating uncertainty applies;
– frequency of the output voltage;
– Designation name of the terminals (if applicable):
– E: terminal for the earth electrode;
– ES: terminal for the probe electrode placed nearest to the earth electrode;
– S: terminal for the probe electrode;
– H: terminal for the auxiliary earth electrode;
– marking for terminals H, S, E and ES according to the requirements of 4.5;
– rated voltage to earth or measuring category and maximum voltage to earth followed by
the symbol according to IEC 61010-1:2010, Table 1, symbol 12.
5.2 Operating instructions
The operating instructions shall state the following in addition to the statements in IEC 61557-
1.
5.2.1 The range of applications (e.g. for agricultural plants or others) for the equipment for
measuring earth resistance.
5.2.2 If applicable, the influence of series interference voltages that are larger than the
values stated under 4.3.
5.2.3 A statement relating to the correct operation of the hand-driven generator (if provided).
5.2.4 The designations of terminals when different from 5.1.3.
In addition to IEC 61557-1:2019, 5.3, the following information shall be provided in the
operating instructions:
– the range of applications (e.g. for industrial plants or others) for the equipment for
measuring resistance to earth;
– the influence of series disturbance voltages that are larger than the values stated in 4.3, if
applicable;
– a statement relating to the correct operation of the hand-driven generator (if provided);
– the designations of terminals when different from those specified in 5.1;
– if applicable, a warning shall be given in the operating instructions that in the case of
Type B clamps the absence of hazardous voltages on the earthing system shall be
checked with two-pole low-voltage detector according to IEC 61243-3.
6 Tests
6.1 General
In addition to IEC 61557-1:2019, Clause 6, the following tests shall be executed performed.

– 10 – IEC 61557-5:2019 RLV © IEC 2019
6.2 Operating uncertainty
The maximum operating uncertainty within the measurement range to be marked or stated
shall be not exceed ±30 % with the measured value as fiducial value, as determined in
accordance with Table 1. In this process, the intrinsic uncertainty shall be determined under
the following reference conditions:
– nominal value of the supply voltage;
– nominal r.p.m. r/min of the hand-driven generator when used as a supply;
– nominal frequency of the power supply in the case of mains-operated measuring
equipment according to 4.3 6.2;
– reference temperature 23 °C ± 2 °C;
– reference position in accordance with the manufacturer's statement;
– resistances of probes and auxiliary earth electrodes at least 100 Ω;
– interference voltage 0 V.
– disturbance voltage less than 1 V.
The operating uncertainty thus evaluated shall not exceed the limits specified in 4.3.

Table 1 – Calculation of operating uncertainty
Requirements or
Intrinsic uncertainty Reference conditions or specified Designation test in accordance Type of
or influence quantity operating range code with the relevant test
parts of IEC 61557
Intrinsic uncertainty Reference conditions Part 5, subclause 6.1
A R
Position Reference position ±90° Part 1, subclause 4.2
approximately
E R
1 IEC 61557-1:2019,
4.2
At the limits stated by the Part 1, subclauses
Supply voltage
manufacturer 4.2, 4.3
E R
IEC 61557-1:2019,
4.2, 4.3
Temperature 0 °C and 35 °C Part 1, subclause 4.2
(± 2°)
E T
3 IEC 61557-1:2019,
4.2
Series interference See 4.2 and 4.3 Part 5, subclauses
disturbance voltage 4.2, 4.3
E T
4.3
Resistance of the Part 5, subclause 4.3
0 R to 100 × R but ≤ 50 kΩ as
A A
probes and auxiliary
defined by the manufacturer
E T
5 IEC 61557-5:2019,
earth electrodes
6.2
System frequency between 99 % and 101 % of the Part 5, subclause 4.3
nominal frequency
E T
7 IEC 61557-5:2019,
6.2
System voltage between 85 % and 110 % of the Part 5, subclause 4.3
nominal voltage
E T
8 IEC 61557-5:2019,
6.2
Operating uncertainty Part 5, subclause 4.3
2 2
BA=±+ E
R
∑ i
i
6.2
Key
A = intrinsic uncertainty
B
E E = variations     B % =±× 100 %

n
i 
F
R = routine test
T = type test
F = fiducial value
The operating uncertainty shall apply under the rated operating conditions given in
IEC 61557-1 and the following:
– injection of series interference disturbance voltages with system frequencies of 400 Hz,
60 Hz, 50 Hz, 16 / Hz (± 5 %) or with DC voltage respectively across the terminals E (ES)
and S or to the earth resistance loop. The RMS value of the series interference
disturbance voltage for equipment with auxiliary probes shall be 3 V (± 5 %);
– for equipment using current clamps, the presence of interfering disturbances shall be
clearly indicated if the influence quantity will exceeds the specified value of the variation
E and of the operating uncertainty. An example of a test configuration for injection of the
series disturbance voltages can be found in Annex A;

– 12 – IEC 61557-5:2019 RLV © IEC 2019
– resistance of the auxiliary earth electrode and of the probes electrodes: 0 to 100 times R
A
but ≤ 50 kΩ;
– system voltages between 85 % and 110 % of the nominal voltage and between 99 % and
101 % of the nominal system frequency for measuring equipment with a mains supply
and/or measuring equipment deriving its output voltage directly from the distribution
system.
6.3 Electrical safety
Check whether the conditions for the open-circuit voltage, short-circuit current and disconnect
delay stated under 4.5 are met in each of the measurement ranges (routine test).
Check whether exceeding the permissible maximum resistances for probes and auxiliary earth
electrodes is indicated (type test).
6.4 The overload protection in accordance with 4.6 shall be tested (type test), when any
plug or socket of the measuring equipment, intended for conncetion to the distribution
system’s power supply is connected to 120 % of its nominal voltage. Protective devices shall
not be activated.
6.5 Compliance with the tests in this clause shall be recorded.

Annex A
(informative)
Recommended test configuration for earth loop clamps
A.1 General
This annex gives a recommended test configuration to inject a series disturbance voltage less
than 1 V to measuring circuits of earth fault loop clamps.
A.2 Test purpose
Influence of current flow on resistance measurement (see Figure A.1 for test arrangement).
10 A ~ (16 / / 50 / 400 Hz)
0,3 Ω
100 Ω
IEC
Figure A.1 – Test arrangement
NOTE For measurement circuit ranges above 100 Ω, the values of resistances and of the current can be changed
accordingly.
A.3 Test result
Load No current 10 A; 16,67 Hz 10 A; 50 Hz 10 A; 400 Hz
Reading 107,2 Ω 108,4 Ω 108,6 Ω 109,4 Ω
Change of reading Reference value 1,12 % 1,31 % 2,05 %

– 14 – IEC 61557-5:2019 RLV © IEC 2019
Bibliography
IEC 60050-161:1990, International Electrotechnical Vocabulary (IEV) – Part 161:
Electromagnetic compatibility
IEC 60050-195:1998, International Electrotechnical Vocabulary (IEV) – Part 195: Earthing and
protection against electric shock

___________
IEC 61557-5 ®
Edition 3.0 2019-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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 5: Resistance to earth
Sécurité électrique dans les réseaux de distribution basse tension au plus égale
à 1 000 V c.a. et 1 500 V c.c. – Dispositifs de contrôle, de mesure ou de
surveillance de mesures de protection –
Partie 5: Résistance à la terre

– 2 – IEC 61557-5:2019 © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Requirements . 7
4.1 General . 7
4.2 Output voltage . 7
4.3 Disturbance voltage . 7
4.4 Permissible resistance of probe and auxiliary earth electrode . 7
4.5 Electrical safety . 7
4.6 Clamps intended to measure earth loop resistances according to
IEC 60364-6:2016, Annex C, Clause C.3 . 8
5 Marking and operating instructions . 8
5.1 Marking . 8
5.2 Operating instructions . 8
6 Tests . 8
6.1 General . 8
6.2 Operating uncertainty . 9
6.3 Electrical safety . 10
Annex A (informative) Recommended test configuration for earth loop clamps . 11
A.1 General . 11
A.2 Test purpose . 11
A.3 Test result. 11
Bibliography . 12

Table 1 – Calculation of operating uncertainty . 9

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 5: Resistance to earth
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.
International Standard IEC 61557-5 has been prepared by IEC technical committee 85:
Measuring equipment for electrical and electromagnetic quantities.
This third edition cancels and replaces the second edition published in 2007. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) definitions and symbols in Clause 3 modified;
b) subclauses in Clause 4 restructured and aligned with other parts of the series;
c) limits for reduced voltages 25 V RMS or 35 V peak removed from 4.5;

– 4 – IEC 61557-5:2019 © IEC 2019
d) requirements for clamps added;
e) marking for rated voltages to earth and measurement category added to Clause 5;
f) warning about absence of hazardous voltage added in Clause 5;
g) the term "percentage operating uncertainty" replaced by "operating uncertainty" in
Clause 6;
h) equation for uncertainty corrected in Table 1;
i) new Annex A on test measurements with loop clamps added.
The text of this International Standard is based on the following documents:
FDIS Report on voting
85/685/FDIS 85/696/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
This International Standard is to be used in conjunction with IEC 61557-1:2019.
A list of all parts of 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 "http://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.
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 5: Resistance to earth
1 Scope
This part of IEC 61557 specifies the requirements applicable to measuring equipment for
measuring the resistance to earth using an AC voltage.
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 60364-6:2016, Low voltage electrical installations – Part 6: Verification
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 61010-2-030:2017, 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 61243-3, Live working – Voltage detectors – Part 3: Two-pole low-voltage type
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
3 Terms and definitions
For the purposes of this document, the terms, definitions and symbols given in IEC 61557-1
and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
—————————
A consolidated version of this publication exists, comprising IEC 61010-1:2010 and
IEC 61010-1:2010/AMD1:2016.
– 6 – IEC 61557-5:2019 © IEC 2019
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
resistance to earth
R
A
real part of the impedance to earth
Note 1 to entry: resistance to ground (US).
Note 2 to entry: IEC 60364-6 uses the term "earth resistance", which is considered to be the same.
[SOURCE: IEC 60050-195:1998, 195-01-18, modified – Notes 1 and 2 to entry and a symbol
have been added.]
3.2
disturbance voltage
voltage produced between two points on two separate conductors by an electromagnetic
disturbance, measured under specified conditions and superimposed on the measuring
voltage
[SOURCE: IEC 60050-161:1990, 161-04-01, modified – in alignment with the use in this
document; in addition, the deprecated term "interference voltage" has been deleted.]
3.3
earth electrode
conductive part, which may be embedded in a specific conductive medium, for example
concrete or coke, in electric contact with the Earth
[SOURCE: IEC 60050-195:1998, 195-02-01, modified – The US variant, "ground electrode"
has been omitted.]
3.4
earth electrode terminal
connection point for a probe connected to the earth electrode to be tested and that is used for
the injection of the test current required for the purpose of measurement
Note 1 to entry: In accordance with the requirements of this document, earth electrode terminals are marked "E".
3.5
earth electrode probe terminal
connection point for a probe connected to the earth electrode to be tested and that is used as
a voltage probe either connected direct to or nearest to the earth electrode for sampling
potentials during measurement
Note 1 to entry: In accordance with the requirements of this document, earth electrode probe terminals are
marked "ES".
3.6
auxiliary earth electrode terminal
terminal for connection to an additional temporary earth electrode that is used for injection of
a test current required for the purpose of measurements
Note 1 to entry: In accordance with the requirements of this document, auxiliary earth electrode terminals are
marked "H".
3.7
auxiliary earth electrode resistance
R
H
resistance of an additional earth electrode
...