IEC TR 63167:2024

IEC TR 63167 ®
Edition 2.0 2024-08
REDLINE VERSION
TECHNICAL
REPORT
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inside
Assessment of contact current related to human exposure to electric, magnetic
and electromagnetic fields
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IEC TR 63167 ®
Edition 2.0 2024-08
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
Assessment of contact current related to human exposure to electric, magnetic
and electromagnetic fields
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20 ISBN 978-2-8322-9537-3

– 2 – IEC TR 63167:2024 RLV © IEC 2024
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Abbreviated terms . 8
5 Contact current in EMF exposure guidelines . 8
6 Consideration in evaluating contact currents . 9
6.1 General . 9
6.2 Assumed situations of human exposure to contact current . 9
6.2.1 General . 9
6.2.2 Capacitive coupling (power line) . 9
6.2.3 Inductive coupling (power line) . 9
6.2.4 Induction heating equipment . 10
6.2.5 Wireless power transfer (WPT) . 10
6.2.6 Broadcasting . 10
6.3 Methods of measurement of touch current used in electrical safety standards . 10
6.3.1 General . 10
6.3.2 IEC standards related to electrical safety . 10
6.3.3 Modelling human body impedance . 14
6.4 Proposed methods of measuring contact current . 19
6.4.1 General . 19
6.4.2 Contact current measurement using a human subject . 20
6.4.3 Contact current measurement using a human equivalent
impedance/circuit. 20
6.4.4 Contact current calculated from measurement of open-circuit voltage . 20
7 Consideration in standardization of evaluation method for contact current . 21
Annexe A (informative) Contact current limits in international EMF guidelines . 22
A.1 General . 22
A.2 Reference levels based on electro-stimulation effects . 22
A.3 Reference levels and a guidance based on thermal effects . 24
Bibliography . 26

Figure 1 – Time/ versus current zones of effects of AC currents (15 Hz to 100 Hz) on
persons for a current path corresponding to left hand to feet (for explanation see
Table 2) . 13
Figure 2 – Measuring network for unweighted touch current . 15
Figure 3 – Measuring network for touch current weighted for perception or startle-
reaction [18]. 16
Figure 4 – Simulated body impedance for contact current
measurements shown in IEEE C95.3 [27] .
Figure 4 – Impedances of various parts of the body proposed in IEC TS 62996 [10] for
1 kHz to 6 MHz . 19
Figure 5 – Realistic computational 3D human body model and results of calculation of
current density and pathway . 21

Table 1 – Selected IEC technical committees and standards related to electrical safety . 12
Table 2 – Time/ versus current zones for AC 15 Hz to 100 Hz for hand to feet pathway
– Summary of zones in Figure 1 . 13
Table A.1 – Reference levels in ICNIRP 2010 guidelines for time varying contact
current from conductive object [1] . 22
Table A.2 – Maximum permissible exposure (MPE) levels
of contact current in IEEE safety standards [3], [4] .
Table A.2 – Exposure reference levels (ERLs) of contact current based on electro-
stimulation effects in IEEE Std C95.1-2019 [3] . 23
Table A.3 – Exposure reference levels (ERLs) of contact current based on thermal
effects in IEEE Std C95.1-2019 [3] . 24

– 4 – IEC TR 63167:2024 RLV © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ASSESSMENT OF CONTACT CURRENT RELATED TO HUMAN EXPOSURE
TO ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS

FOREWORD
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This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC TR 63167:2018. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
IEC TR 63167 has been prepared by IEC technical committee 106: Methods for the assessment
of electric, magnetic and electromagnetic fields associated with human exposure. It is a
Technical Report.
This second edition cancels and replaces the first edition published in 2018. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) revised in accordance with the latest revision of international EMF guidelines;
b) revised in accordance with updates of relevant IEC standards on electrical safety.
The text of this Technical Report is based on the following documents:
Draft Report on voting
106/641/DTR 106/656/RVDTR
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 Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
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– 6 – IEC TR 63167:2024 RLV © IEC 2024
INTRODUCTION
In the guidelines limiting human exposure to electric, magnetic and electromagnetic fields (EMF
guidelines), limits or a guidance for the contact current are given to avoid adverse indirect
effects, i.e. electric shocks and burn hazards caused by contact with a conductive object located
in an electric field or magnetic field or both, when the object has an electric potential owing to
electric or magnetic induction to the object.
At the moment, no standardized method for evaluating the contact current, in the context of
human exposures to the above fields has been well established. On the other hand, there is a
vast amount of knowledge, as well as many standards and regulations on the issue of electrical
safety (i.e. direct contact with live part of conductive object) to avoid severe electric shock
hazards. Therefore, the evaluation methods used in the field of electrical safety might can be
useful references. This document summarizes general information on the assessment of
contact current related to human exposure to electric, magnetic and electromagnetic fields.

ASSESSMENT OF CONTACT CURRENT RELATED TO HUMAN EXPOSURE
TO ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS

1 Scope
This document, which is a Technical Report, provides general information on the assessment
of contact current related to human exposure to electric, magnetic and electromagnetic fields.
The contact currents in this context occur when a human body comes into contact with a not
electrified conductive object that is non-electrified but exposed to an electric field or magnetic
field or both at a different electric potential owing to electric and/or magnetic induction to the
object. This is distinguished from the issue of electrical safety where contact with live parts of
a conductive object is dealt with.
In reference to the international EMF guidelines [1], [2], and [3] , the frequency range of contact
current covered in this document is DC to 110 MHz, and only steady-state (continuous) contact
currents are covered. Transient contact currents (spark discharges) which may can occur
immediately before the contact with the object are not covered.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
contact current
current flowing into the body resulting from contact with a conductive object in an electric,
magnetic or electromagnetic field
current flowing through the body resulting from contact with an insulated
conductive object that has been energized in an electric, magnetic or electromagnetic field or
from an insulated body that has been energized in an electric, magnetic or electromagnetic field
and is in contact with a grounded conductive object
3.2
electric field strength
magnitude of a field vector at a point that represents the force (F) on an infinitely small charge
(q) divided by the charge
___________
Numbers in square brackets refer to the Bibliography.

– 8 – IEC TR 63167:2024 RLV © IEC 2024
3.2
exposure
state situation that occurs when a person is subjected to an electric, magnetic or
electromagnetic field, or to a contact current other than those originating from physiological
processes in the body and other natural phenomena
3.3
indirect effect
effect resulting from physical contact between a person and a not electrified object, such as a
metallic structure in an electric, magnetic or electromagnetic field, at an electric potential that
is at least at a point of the object different from the potential of the person
effect arising when an object present in an electromagnetic field becomes a cause of safety or
health hazard
3.4
touch current
electric current flowing passing through a human body when it touches one or more accessible
and energized parts of an installation or of equipment, or object, used in the field of electrical
safety
Note 1 to entry: The term "leakage current" had also been used as a synonym for touch current in the field of
electrical safety.
[SOURCE: IEC 60050-195:2021, 195-05-21, modified – In the definition, "or through livestock"
has been deleted, "and energized" has been added, "or object, used in the field of electrical
safety" has been added. Note 1 to entry has been added.]
3.5
spark discharge
transfer of current through an air gap prior to making contact with another conductive object at
a different potential
4 Abbreviated terms
3D three dimensional
AC alternating current
AM amplitude modulation
DC direct current
EMF electric, magnetic or electromagnetic field
EV electric vehicle
FM frequency modulation
ICNIRP International Commission on Non-Ionizing Radiation Protection
IEEE Institute of Electrical and Electronics Engineers
IH induction heating
MPE maximum permissible exposure
MRI magnetic resonance imaging
PC personal computer
RF radio frequency
WPT wireless power transfer
5 Contact current in EMF exposure guidelines
Clause 5 overviews contact currents described in the EMF guidelines [1], [2], and [3].

In the frequency range up to approximately 10 MHz (predominantly up to 100 kHz), the flow of
electric current from an object in a field to the body of an individual may can result in the
stimulation of muscles and/or peripheral nerves. With increasing current, this may can be
manifested as perception, pain from an electric shock and/or burn, the inability to release the
object, difficulty in breathing and, at higher currents, cardiac ventricular fibrillation.
In the frequency range of about 100 kHz to 110 MHz, shocks and burns can result either from
an individual touching an ungrounded metal object that has acquired a charge in a field or from
contact between a charged individual and a grounded metal object.
In the EMF guidelines, reference levels or a guidance for steady state (continuous) contact
current are given for frequencies up to 110 MHz to avoid shock and burn hazards (see Annex A) ,
rather than to avoid ventricular fibrillation. The reference levels are not intended to avoid
ventricular fibrillation, which is the basis of standards for electrical safety. The upper frequency
of 110 MHz is the upper frequency limit of the FM broadcast band. Here, the transient currents
resulting from spark discharges [4], which can occur when an individual comes into very close
proximity with an object at a different electric potential, are not considered in the reference
levels of contact current. Instead, the effect of spark discharge is considered in the reference
levels of electric field exposure for the general public by including a sufficient margin to prevent
surface electric-charge effects such as perception by most people.
It is noteworthy that different methods for evaluation of conformity to the guidelines are provided
for multiple-frequency exposure for low-frequency (below 100 kHz) and high-frequency (above
10 kHz) ranges. In the frequencies between 10 kHz and 100 kHz, both evaluation methods are
applied (see Annex A).
6 Consideration in evaluating contact currents
6.1 General
Clause 6 describes items to be considered in evaluating contact currents:
a) assumed situations of human exposure to a contact current (6.2);
b) methods for evaluating a touch current used in electrical safety standards for
references (6.3);
c) some proposed methods for evaluating contact currents (6.4).
6.2 Assumed situations of human exposure to contact current
6.2.1 General
There are several situations to be considered for human exposure to a contact current. Different
cases have to be are considered depending on the type of coupling between fields (electric or
magnetic) and human bodies/ or objects.
6.2.2 Capacitive coupling (power line)
An electric field induces, by capacitive coupling (electrostatic induction), a voltage in a person
or a conductive object that is isolated from the ground. When a person touches an object having
a different potential, a contact current flows so as to cancel the potential difference. This can
be categorized into two cases: (a) an isolated person touches a grounded object and (b) a
grounded person touches an isolated object (especially a large object such as a bus or a
truck) [5]. Comprehensive studies have been carried out for typical cases encountered under
overhead transmission lines [6].
6.2.3 Inductive coupling (power line)
By inductive coupling (electromagnetic induction), a magnetic field induces a voltage, especially
in long conductive objects such as telecommunication lines, fences and gas pipelines, having

– 10 – IEC TR 63167:2024 RLV © IEC 2024
at least one reasonable grounding, when they are installed close to and parallel to magnetic
field sources such as overhead power lines [7]. When a person touches the object, a contact
current flows. In particular, in the case of fault condition in overhead power lines, the limit values
for the open-circuit voltage in nearby telecommunication lines are set by an international
regulation-setting body [8]. In contrast to the capacitive coupling, grounding a conductive object
at a large distance from the point of contact will actually increase the amplitude of the open-
circuit voltage, thereby increasing the contact current.
6.2.4 Induction heating equipment
Induction heating (IH) equipment is heating equipment using the Joule effect produced by
magnetically induced currents. For a domestic IH cooker, a metal pan or pot is heated by a
magnetic field, and when a person touches a conductive part of the pan or pot, a contact current
can occur typically in the frequency ranges of around 20 kHz to 100 kHz. The method used to
evaluate human exposure to magnetic fields produced by IH cookers is standardized in
IEC 62233 [9]; however, the contact currents are not mentioned in IEC 62233. Note that it may
be appropriate to categorize this exposure situation as an issue of electrical safety.
For industrial IH equipment, a method of evaluating touch current in terms of electrical safety
is being standardized in IEC TC 27 (industrial electroheating and electromagnetic processing)
specified in IEC TS 62996 [10] for the frequency ranges between 1 kHz and 6 MHz.
6.2.5 Wireless power transfer (WPT)
A wireless power transfer (WPT) system is a system capable of transferring power between a
transmitter and receiver using wireless technologies including electromagnetic induction,
resonance, or capacitance. They are used for wirelessly charging mobile phones, tablet PCs,
electric vehicles (EVs) and, so forth. There are several types of WPT, and the frequency ranges
is can vary from tens of kilohertz to tens of megahertz. When a conductive object is placed in
the immediate vicinity of a system and a person touches it, a contact current can occur, such
as by touching the metal body of an EV when charging with a WPT charging system [11]. As
touching the metal body of an EV when charging using a WPT charging system may be the
case [12], it may be appropriate to categorize the exposure situation as an issue of electrical
safety. Details regarding exposure assessment methods for WPT systems are reported in
IEC TR 62905 [12] and IEC PAS 63184 [13]. In IEC TR 62905 these publications, contact
currents are considered for the conditions where an ungrounded or grounded metal object is
placed in the vicinity of WPT systems.
6.2.6 Broadcasting
Burns can occur at a point of contact between a human body and a metallic structure that is
exposed to RF electromagnetic fields from nearby sources such as AM broadcast antennas.
The contact point between the body and the structure often has a small area and the current
injected into the body is concentrated near this point. This can result in localized current density
near the contact sufficiently densities strong enough to raise the local temperature and cause
surface or deep burns [14].
6.3 Methods of measurement of touch current used in electrical safety standards
6.3.1 General
When considering the evaluation method for contact currents in the context of human exposure
to electric, magnetic and electromagnetic fields, existing IEC standards related to electrical
safety may be can provide some useful inputs guidance.
6.3.2 IEC standards related to electrical safety
There are several IEC technical committees in charge of electrical safety. These include:
– TC 64: Electrical installations and protection against electric shock;

– TC 108: Safety of electronic equipment within the field of audio/video, information
technology and communication technology;
– TC 61: Safety of household and similar electrical appliances;
– TC 99: System engineering and erection of electrical power installations in systems with
nominal voltages above 1 kV AC and 1,5 kV DC, particularly concerning safety aspects;
– TC 66: Safety of measuring, control and laboratory equipment;
– TC 62/SC 62A: Common aspects of electrical equipment used in medical practice.
Table 1 summarizes the selected standards related to the electrical safety and the committees
in which they were created. Note that the "touch voltage", the product of the touch current and
the assumed body impedance, is commonly used as a parameter for setting limits for touch
currents.
In IEC TS 60479-1 [15], a diagram of physiological effects for different touch currents and
durations is shown (reproduced in Figure 1 and Table 2), which is commonly referenced in
electrical safety standards as a basis for limiting touch currents.

– 12 – IEC TR 63167:2024 RLV © IEC 2024
Table 1 – Selected IEC technical committees and standards related to electrical safety
IEC TC IEC standards related to electrical safety Notes
TC 108, Safety of electronic equipment IEC 60065:2014, Audio, video and similar Stipulates touch
within the field of audio/video, information electronic apparatus – Safety requirements voltage limits
technology and communication technology [16]
IEC 60950-1:2005, Information technology Stipulates touch
equipment – Safety – Part 1: General current limits
requirements
IEC 60950-1:2005/AMD1:2009
IEC 60950-1:2005/AMD2:2013 [17]
IEC 60990:2016, Methods of measurement of Stipulates
touch current and protective conductor measuring method
current [18] of touch current
IEC 62368-1:20142023, Audio/video, “Hazard based
information, and communication technology safety engineering
equipment – Part 1: Safety requirements [19] (HBSE)” is adopted
Stipulates
prospective touch
voltage and touch
current limits
TC 61, Safety of household and similar IEC 60335-1:20102020, Household and Stipulates touch
electrical appliances similar electrical appliances – Safety – Part current limits
1: General requirements [20]
IEC 60335-1:2010/AMD1:2013
IEC 60335-1:2010/AMD2:2016 [18]
TC 64, Electrical installations and protection IEC 60364-4-41:2005, Low-voltage electrical
against electric shock installations – Part 4-41: Protection for safety
– Protection against electric shock [21]
IEC 60364-4-41:2005/AMD1:2017
IEC TS 60479-1:20052018, Effects of A diagram of
current on human beings and livestock – Part physiological
1: General aspects [15] effects for different
body currents and
IEC TS 60479-1:2005/AMD1:2016 [20]
durations is shown
IEC TS 60479-2:20172019, Effects of
current on human beings and livestock – Part
2: Special aspects [22]
IEC 61140:2016, Protection against electric
shock – Common aspects for installation and
equipment [23]
IEC TS 61201:2007, Use of conventional
touch voltage limits – Application guide [24]
TC 99, Insulation co-ordination and system IEC 61936-1:20102021, Power installations Stipulates touch
engineering of high voltage electrical power exceeding 1 kV AC and 1,5 kV DC – Part 1: voltage limits
installations above 1,0 kV AC and 1,5 kV DC Common rules AC [25]
IEC 61936-1:2010/AMD1:2014
TC 66, Safety of measuring, control and IEC 61010-1:2010, Safety requirements for Stipulates touch
laboratory equipment electrical equipment for measurement, current limits
control, and laboratory use – Part 1: General
requirements
IEC 61010-1:2010/AMD1:2016 [26]
TC 62/SC 62A, Common aspects of electrical IEC 60601-1:2005, Medical electrical Stipulates "leakage
equipment used in medical practice medical equipment – Part 1: General requirements current" limits
equipment, software, and systems for basic safety and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 60601-1:2005/AMD2:2020 [27]

SOURCE: Figure 20 in IEC 60479-1:2018 [15].
Figure 1 – Time/ versus current zones of effects of AC currents (15 Hz to 100 Hz)
on persons for a current path corresponding to left hand to feet
(for explanation see Table 2)
Table 2 – Time/ versus current zones for AC 15 Hz to 100 Hz for
hand to feet pathway – Summary of zones in Figure 1
Zones Boundaries Physiological effects
AC-1 Up to 0,5 mA curve a Perception possible but usually no "startled" reaction
AC-2 0,5 mA up to curve b Perception and involuntary muscular contractions likely but usually no
harmful electrical physiological effects
AC-3 Curve b and above Strong involuntary muscular contractions. Difficulty in breathing.
Reversible disturbances of heart function. Immobilization may can
occur. Effects increasing with current magnitude. Usually, no organic
damage to be expected
a
Above curve c Patho-physiological effects may can occur such as cardiac arrest,
AC-4
breathing arrest, and burns or other cellular damage. Probability of
ventricular fibrillation increasing with current magnitude and time
Between curves c and c AC-4.1 Probability of ventricular fibrillation increasing up to about 5 %
1 2
Between curves c and c AC-4.2 Probability of ventricular fibrillation up to about 50 %
2 3
Beyond curve c AC-4.3 Probability of ventricular fibrillation above 50 %
a
For durations of current flow below 200 ms, ventricular fibrillation is only initiated within the vulnerable period
if the relevant thresholds are surpassed. As regards ventricular fibrillation, Figure 1 relates to the effects of
current which flows in the path left hand to feet. For other current paths, the heart current factor has to be is
considered.
SOURCE: Table 11 in IEC 60479-1:2018 [15].

– 14 – IEC TR 63167:2024 RLV © IEC 2024
6.3.3 Modelling human body impedance
6.3.3.1 General
An impedance or an equivalent circuit of the human body is needed when deriving a touch
voltage from a permissible touch current. In addition, when measuring touch or contact current,
an appropriate circuit should be is standardized. The following considerations have been made
regarding the standardization of electrical safety.
6.3.3.2 Dependence of human impedance on touch voltage
In IEC TS 60479-1 [15], it is shown that the impedance of the human body varies with the touch
voltage, and data on this relationship are provided. In addition, the impedance of the human
body for different current paths is also considered.
6.3.3.3 Frequency characteristics
In IEC 60990 [18], circuits that simulate the frequency characteristics of human body impedance
are shown for the measurement of touch currents to be used for frequencies up to 1 MHz. The
circuit shown in Figure 2 is for an "unweighted" touch current to be adopted for burns, while the
circuit shown in Figure 3, which includes a weighting circuit, considers the human response of
perception or reaction.
A similar circuit is also shown in IEEEC 95.3 [27] (Figure 4) IEEE Std C95.3™-2021 [28]. In
IEEE C95.3, a simulated body impedance (standard load) that can be inserted in the
measurement circuit when measuring the contact current is shown.

A
R
S
C
S
Test terminals
B R U
B 1
IEC
Key
R 1 500 Ω
S
R 500 Ω
B
C 0,22 µF
S
U
Unweighted touch current = (RMS value)
Key
R = 1 500
S
R = 500
B
C = 0,22
S
R resistance (Ω)
C capacitance (µF)
U voltage (V)
SOURCE: Figure 3 in IEC 60990:2016 [18].
Figure 2 – Measuring network for unweighted touch current [16]

– 16 – IEC TR 63167:2024 RLV © IEC 2024
A
R
S
C
S
Test terminals R
B R U U
B 1 2
C
IEC
Key
R 1 500 Ω R 10 000 Ω
S 1
R 500 Ω C 0,022 µF
B 1
C 0,22 µF
S
U
Weighted touch current (perception or startle-reaction) = (peak value)
Key
R = 1 500
S
R = 500
B
C = 0,22
S
R = 10 000
C = 0,022
R resistance (Ω)
C capacitance (µF)
U voltage (V)
SOURCE: Figure 4 in IEC 60990:2016 [18].
Figure 3 – Measuring network for touch current weighted
for perception or startle-reaction [18]

10 kΩ
1 kΩ
Z
0,015 µF
V
meas
IEC
Figure 4 – Simulated body impedance for contact current
measurements shown in IEEE C95.3 [27]
6.3.3.4 Consideration of touching boundary (skin impedance and contact area)
Well-investigated circuits for the human body impedance considering electrodes, skin
impedances and spreading impedances have also been proposed for the frequency ranges from
10 kHz to 10 MHz [29] and from 75 kHz to 15 MHz [30] based on measurements made on
human subjects. In IEC TS 62996 [10], which deals with the electrical safety of industrial
electroheating and electromagnetic processing equipment, the circuit proposed in [29] was
adopted with minor modification for frequencies from 1 kHz to 6 MHz.
In addition, the area of contact is stipulated in the safety standards to properly simulate the
touching condition in measurements. In the proposed circuits in [10] (Figure 4), [29] and [30],
"grip" and "finger" contacts can be considered. In the EMF guidelines (see Annex A), the
assumed conditions of contact are "point contact" (area not specified) in ICNIRP guidelines [1],
and "touch contact" with a contact area of 1 cm and "grasping contact" (applicable only for a
controlled environment "persons permitted in restricted environments") with a contact area of
15 cm for the IEEE safety standard [3].

– 18 – IEC TR 63167:2024 RLV © IEC 2024
Skin Spread
Primary
contact area
R C R
s s t
Skin and adjacent tissue
5n 160p
Gripping
(closed)
Finger
Finger
740 730 430
R = 3 × 10 / (ƒA) Ω
s contact
–4
C = 1 × 10 A µF (open)
s
R = 1 500 /√A Ω
t
Where ƒ is in Hz and A in mm
1,3n
Sum of arm,
torso and leg 540
1,8k
Connection to
secondary contact area
IEC
Key
R = (3 × 10 ) · f · A
s
−4
C = (1 × 10 ) · A
s
−1/2
R = 1 500 · A
t
where
R , R is the impedance in units of Ω;
s t
C is the capacitance, in units of μF;
s
A is the area of contact, in units of mm ;
f is the frequency, in units of Hz.
SOURCE: Kanai et al. [29]. Reproduced with permission of IEEE.
Figure 4 – Impedances of various parts of the body proposed
in IEC TS 62996 [10] for 1 kHz to 6 MHz
6.4 Proposed methods of measuring contact current
6.4.1 General
In 6.4, possible evaluation methods for the measurement of contact currents (or contact
voltages) are described. To estimate the contact current, the methods in 6.4.2, 6.4.3 and 6.4.4
can be applied.
– 20 – IEC TR 63167:2024 RLV © IEC 2024
6.4.2 Contact current measurement using a human subject
It is straightforward to measure a contact current directly using a human subject itself for an
exposure situation to be tested; however, special care must be taken to ensure the safety of
the subject to avoid electric shock. This method is considered in Annex D of IEC 62311:2007,
a generic IEC standard for EMF exposure [30]. For this case, a clamp-on current sensor (current
transformer) can be used to measure the contact current flowing into a hand in contact with a
conductive object. The contact current exposure situation can be measured using a human
subject; however, it is important to take special care to ensure the safety of the subject to avoid
electric shock. For this case, a clamp-on current sensor (current transformer) can be used to
measure the contact current flowing into a hand in contact with a conductive object. An
alternative approach would be to use a pistol grip device held in the operator's hand with the
tip of the device making contact with the conductive object which protects the operator from
spark discharge to the body surface. Current is measured within the device, and the broad
contact of the operator's palm with the device dilutes the current density from the device to the
operator over a large skin area. Another proposed method is measurement of the voltage
difference between points of concern on a human body [31]. In this case, the contact current
can be calculated from the obtained voltage difference and information on the impedance of the
body between the points.
6.4.3 Contact current measurement using a human equivalent impedance/circuit
Considering the safety of human subjects and the repeatability of measurements, it is more
suitable to use an impedance or a circuit that simulates the human body as a standardized
measurement method for contact currents. The human-equivalent circuits shown in 6.3.3 can
be used for this purpose.
In addition, for standardization, the area of the contact and the grounding condition should are
also be specified to ensure repeatability.
There are is some products measurement equipment that are is commercially available, for
frequencies of 3 kHz to 3 MHz and for frequencies from 40 Hz to 110 MHz, for example. These
instruments have a human equivalent circuit and provide a flat metal plate used as a ground
plane. One of these instruments is capable of choosing a grasp or touch contact, while the other
can measure the contact current through a real human body.
6.4.4 Contact current calculated from measurement of open-circuit voltage
An alternative method is to measure the open-circuit voltage (contact voltage) of a conductive
object to be touched instead of the measurement of a contact current. The contact current can
then be obtained by a calculation using the obtained voltage and information on the human-
equivalent circuit.
For the calculation, the human-equivalent circuits shown in 6.3.3 can be used. In addition, more
realistic human models with a few millimetre resolution have been developed for numerical
calculation [32], [33], [34], [35], [36], [37], and these models can be applied for this purpose.
The realistic computational 3D human body model is derived from 3D imaging technology such
as MRI and CT scans, and the images are then meshed into voxels for numerical analysis. Such
model and methodology can provide much more precise results than the simple circuit model.
A typical human body model grasping an energized metal electrode is shown in Figure 5. The
figure also shows the current density plots and current pathways that result through the
computational human body using typical numerical electromagnetic simulation tools. When
including such kind of a realistic human model into a standard, the detail of the model should
be transparent is specified.
Figure 5 – Realistic computational 3D human body model
and results of calculation of current density and pathway
7 Consideration in standardization of evaluation method for contact current
At the moment, there are no standardized methods for evaluating the contact currents in the
context of human exposure to electric, magnetic and electromagnetic fields. In this Clause 7,
items to be considered in future standardization are discussed.
a) Scope: A future standard should will clarify its scope, i.e. it should will be limited to the issue
of contact current related to the indirect effect of human exposure to electromagnetic fields,
and exclude electrical safety issues. In addition, it should will be clearly stated that only
steady-state contact current as shown in international EMF guidelines is dealt with and that
spark discharge is exc
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