IEC TR 60479-5:2007

Effects of current on human beings and livestock - Part 5: Touch voltage threshold values for physiological effects

This Technical Report provides touch voltage-duration combination thresholds based on analysis of information concerning body impedances and current thresholds of physiological effects, as given in IEC/TS 60479-1. Such threshold combinations relate to specific environmental and contact conditions that determine body impedance for particular current pathways. This technical report considers only (i) 50/60 Hz sinusoidal alternating voltage having no other frequency components and no significant direct voltage component, and (ii) direct voltage with no significant alternating component. This technical report provides thresholds as a result of calculations based on values from IEC/TS 60479-1, with uncertainties. Therefore thresholds proposed in this report also correspond to values with uncertainties. Touch voltage-duration combination thresholds are for use by technical committees as guidance for the determination of limits for touch voltage and touch voltage durations in various environmental situations. The contents of the corrigendum of July 2013 have been included in this copy.

Effets du courant sur l'homme et les animaux domestiques - Partie 5: Valeurs des seuils de tension de contact pour les effets physiologiques

Ce rapport technique fournit les seuils de combinaison temps-tension de contact basés sur une analyse des valeurs des impédances du corps humain et des seuils de courant pour des effets physiologiques donnés tels que fournis dans la CEI/TS 60479-1. Ces seuils de combinaison temps-tension de contact se rapportent à des conditions d'environnement particulier et à des conditions de contact qui déterminent l'impédance du corps humain pour des cheminements particuliers du courant. Ce rapport technique considère uniquement (i) les tensions alternatives sinusoïdales de fréquence 50/60 Hz n'ayant aucune composante de fréquence différente ainsi qu'aucune composante continue significative, ou (ii) des tensions continues avec aucune composante alternative significative. Ce rapport technique fournit les seuils résultant de calculs basés sur les valeurs de la CEI/TS 60479-1 avec des incertitudes. Ainsi, les seuils proposés dans le présent rapport technique correspondent à des valeurs ayant des incertitudes. Les seuils de combinaison temps-tension de contact sont destinés à être utilisés par les comités d'études en tant que lignes directrices pour la détermination des limites de tensions de contact et des durées des tensions de contact dans plusieurs situations d'environnement. Le contenu du corrigendum de juillet 2013 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 06-Nov-2007
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 13.200 - Accident and disaster control
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: TC 64 - Electrical installations and protection against electric shock
• Drafting Committee: MT 4 - TC 64/MT 4
• Current Stage: PPUB - Publication issued
• Start Date: 31-Dec-2007
• Completion Date: 07-Nov-2007

Standards Content (Sample)

IEC/TR 60479-5
Edition 1.0 2007-11
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Effects of current on human beings and livestock –
Part 5: Touch voltage threshold values for physiological effects

Effets du courant sur l’homme et les animaux domestiques –
Partie 5: Valeurs des seuils de tension de contact pour les effets physiologiques

IEC/TR 60479-5:2007

---------------------- Page: 1 ----------------------
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IEC/TR 60479-5
Edition 1.0 2007-11
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Effects of current on human beings and livestock –
Part 5: Touch voltage threshold values for physiological effects

Effets du courant sur l’homme et les animaux domestiques –
Partie 5: Valeurs des seuils de tension de contact pour les effets physiologiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XA
CODE PRIX
ICS 13.200; 29.020 ISBN 2-8318-9346-1

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– 2 – TR 60479-5 © IEC:2007
CONTENTS
FOREWORD.5
INTRODUCTION.7

1 Scope.8
2 Normative references .8
3 Terms and definitions .9
4 Conditions and threshold values .9
4.1 General .9
4.2 Physiological effects of touch current .10
4.3 Body impedance.14
4.4 Impedance external to the body.15
4.5 Other factors affecting voltage thresholds .15
4.6 Touch voltage thresholds as a function of duration .16
4.7 Touch voltage thresholds for long durations .17
5 Touch voltage thresholds – Presentation of voltage-time curves .19

Annex A (informative) Body impedance.30
Annex B (informative) Touch voltage – Explanation of a method to derive estimates of
touch voltages thresholds for strong muscular reactions and ventricular fibrillation from
the body impedance tables and current limits in IEC/TS 60479-1 .36
Annex C (informative) Determination of voltage thresholds under selected conditions.53
Annex D (informative) Limits of applicability.54

Bibliography.56

Figure 1 – Physiological thresholds for a.c. (50/60-Hz) and d.c. flowing hand-to-hand
(transversely) through the human body .11
Figure 2 – Physiological thresholds for a.c. (50/60-Hz) and d.c. flowing from both
hands to both feet (longitudinally) through the human body .12
Figure 3 – Physiological thresholds for a.c. (50/60-Hz) and d.c. flowing from hand-to
seat (longitudinal) through the human body .13
Figure 4 – Flow chart to be used for the selection of the appropriate figure providing
the maximum duration for each touch voltage threshold.17
Figure 5 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a

person for saltwater-wet condition and large contact area.20
Figure 6 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for saltwater-wet condition and medium contact area .21
Figure 7 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for saltwater-wet condition and small contact area .21
Figure 8 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a

person for water-wet condition and large contact area .22
Figure 9 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for water-wet condition and medium contact area.22
Figure 10 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for water-wet condition and small contact area .23

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TR 60479-5 © IEC:2007 – 3 –
Figure 11 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for dry condition and large contact area .23
Figure 12 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for dry condition and medium contact area .24
Figure 13 – Conventional time/voltage zones of effects of a.c. current (50/60 Hz) on a
person for dry condition and small contact area .24
Figure 14 – Conventional time/voltage zones of effects of d.c. current on a person for
saltwater-wet condition and large contact area .25
Figure 15 – Conventional time/voltage zones of effects of d.c. current on a person for
saltwater-wet condition and medium contact area .25
Figure 16 – Conventional time/voltage zones of effects of d.c. current on a person for
saltwater-wet condition and small contact area .26
Figure 17 – Conventional time/voltage zones of effects of d.c. current on a person for
water-wet condition and large contact area .26
Figure 18 – Conventional time/voltage zones of effects of d.c. current on a person for
water-wet condition and medium contact area.27
Figure 19 – Conventional time/voltage zones of effects of d.c. current on a person for
water-wet condition and small contact area.27
Figure 20 – Conventional time/voltage zones of effects of d.c. current on a person for
dry condition and large contact area .28
Figure 21 – Conventional time/voltage zones of effects of d.c. current on a person for
dry condition and medium contact area.28
Figure 22 – Conventional time/voltage zones of effects of d.c. current on a person for
dry condition and small contact area.29
Figure A.1 – Model for hand-to-hand contact .33
Figure A.2 – Model for both-hands-to-feet contact .34
Figure A.3 – Model for hand-to-seat contact .35
Figure B.1 – Estimation of the variation of the skin resistance as a function of electric
shock duration .38
Figure B.2 – Example of extrapolation of the hand-to-hand body impedance at 0 V in
dry conditions with large contact area .42
Figure B.3 – Percentage of internal resistance of the human body for the part of the
body concerned .43
Figure B.4 – Example of diagram for the estimation of the strong muscular reactions
and ventricular fibrillation threshold for a.c. current hand-to-hand current path, large
contact area and dry condition for a current duration of 10 ms .47

Table 1 – Current threshold values for each condition and for long duration.14
Table 2 – Tables providing minimum touch voltage threshold for a.c. and d.c.
corresponding to startle reaction, strong muscular reaction and ventricular fibrillation
(see Table 1 notes).18
Table 2a – Startle reaction for alternating current 50/60 Hz .18
Table 2b – Strong muscular reaction for alternating current 50/60 Hz .18
Table 2c – Ventricular fibrillation for alternating current 50/60 Hz .18
Table 2d – Startle reaction for direct current .19
Table 2e – Strong muscular reaction for direct current .19
Table 2f – Ventricular fibrillation for direct current.19
Table A.1 – Total body impedance in ohms for dry, hand-to-hand, 50/60 Hz a.c., large
surface area contact (IEC/TS 60479-1 Table 1) .31

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– 4 – TR 60479-5 © IEC:2007
Table A.2 – Total body impedance in ohms for dry, hand-to-hand, d.c., large surface
area contact (IEC/TS 60479-1 Table 10) .31
Table B.1 – Nature and number of the parameters influencing the human body
impedance which are taken into consideration by IEC/TS 60479-1.37
Table B.2 – Additional parameters influencing the human body impedance.37
Table B.3 – Maximum a.c. current threshold corresponding to current flow duration for
each current effect considered and for a hand-to-hand current path.46
Table B.4 – Maximum a.c. current threshold corresponding to current flow duration for
each current effect considered for both-hands-to-feet current path.47
Table B.5 – Maximum a.c. current threshold corresponding to current flow duration for
each current effect considered for a hand-to-seat current path.48
Table B.6 – Maximum d.c. current threshold corresponding to current flow duration for
each current effect considered for the hand-to-hand current path.51
Table B.7 – Maximum d.c. current threshold corresponding to current flow duration for
each current effect considered for the both-hands-to-feet current path.52
Table B.8 – Maximum d.c. current threshold corresponding to current flow duration for
each current effect considered for the hand-to-seat current path.52
Table C.1 – Example of touch voltage thresholds for a.c. and d.c. corresponding to
muscular effects and ventricular fibrillation for the above specified environmental
situations .53

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TR 60479-5 © IEC:2007 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

EFFECTS OF CURRENT ON HUMAN BEINGS AND LIVESTOCK –

Part 5: Touch voltage threshold values for physiological effects


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
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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.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC/TR 60479-5, which is a technical report, has been prepared by IEC technical committee
64: Electrical installations and protection against electric shock.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
64/1585/DTS 64/1611/RVC

Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

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– 6 – TR 60479-5 © IEC:2007
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 60479 series, under the general title Effects of current on
human beings and livestock, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of July 2013 have been included in this copy.

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TR 60479-5 © IEC:2007 – 7 –
INTRODUCTION
This technical report provides a methodology for estimating voltage thresholds which are
intended to give guidance to IEC technical committees on the selection and application of
voltage limits with regard to protection against electric shock. Technical committees may use
this methodology to recalculate proposed voltage thresholds or to determine new voltage
threshold values based on different pathways, other current threshold values, different
alternating current frequencies, other skin capacitances values, etc.
To estimate the type and severity of physiological effects that might be caused by electricity,
the magnitude and pathway of current through a person’s body needs to be determined.
However, from an equipment design point of view, it is advantageous to be able to predict
whether unwanted physiological effects are possible or probable, given only information about
voltage levels on accessible conductive surfaces. If the maximum available voltage is
sufficiently low under the expected circumstances to be unable to cause enough touch current
to cause unwanted physiological effects, then the safeguards normally required to avoid the
occurrence of these physiological effects may be reduced or eliminated. Voltages below
critical levels that are unlikely to be hazardous in this respect have normally been called
extra-low voltage (ELV). Based on this information technical committees may wish to review
their defined values of extra-low voltage.
The objective of this technical report being to derive touch voltage threshold values
corresponding to zones of physiological effects (as presented in Figures 20 and 22 of IEC/TS
60479-1), the introduction of such techniques gives designers the ability to provide a larger
variety of circuits that give the expected level of user protection under a broader set of
circumstances than previously considered.
The physiological effects corresponding to the threshold voltage values should be the same
as those for touch current that appear in IEC/TS 60479-1. Physiological effects considered in
this technical report are startle reaction of current, effects involving muscular contractions
such as inability to let-go and ventricular fibrillation. Current thresholds are based on curves
a, b and c in IEC/TS 60479-1 which remains the prime standard. The touch voltage
1
thresholds are related to the touch current thresholds by the body impedance according to
Ohm’s law. However, in this case, the application of Ohm’s law is not straightforward. Body
impedance is a function of a number of variables including the voltage across the body, the
current pathway, the area of contact between the skin and the conductive surface, the level of
moisture in the contact area, and the duration of voltage across (or current through) the body.
When voltage is applied to the body and current begins to flow, the resistive component of the
skin impedance changes to a lower value within a few tens of milliseconds.
This technical report discusses 50/60Hz sinusoidal alternating voltage and pure direct voltage
having no significant alternating component. Higher frequency alternating voltage is not
included in this type of analysis as this would require a more complex body impedance model
and would require the use of frequency factors for the current thresholds for the unwanted
physiological effects. As this technical report does not cover frequencies above 50/60Hz,
technical committees are requested to inform IEC/TC 64 about experience gained on this
subject. Suggestions for modifications and additions to the report should be submitted to
IEC/TC 64.
This work does not relieve the responsibility of IEC technical committees to consider the usual
touch current commonly measured in product evaluations.

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– 8 – TR 60479-5 © IEC:2007
EFFECTS OF CURRENT ON HUMAN BEINGS AND LIVESTOCK –

Part 5: Touch voltage threshold values for physiological effects



1 Scope
IEC/TR 60479-5, which is a technical report, provides touch voltage-duration combination
thresholds based on analysis of information concerning body impedances and current
thresholds of physiological effects, as given in IEC/TS 60479-1. Such threshold combinations
relate to specific environmental and contact conditions that determine body impedance for
particular current pathways.
This technical report considers only
(i) 50/60 Hz sinusoidal alternating voltage having no other frequency components and no
significant direct voltage component, and
(ii) direct voltage with no significant alternating component.
This technical report provides thresholds as a result of calculations based on values from
IEC/TS 60479-1, with uncertainties. Therefore thresholds proposed in this report also
correspond to values with uncertainties.
This technical report does not consider immersion of body parts and medical application.
Touch voltage-duration combination thresholds are for use by technical committees as
guidance for the determination of limits for touch voltage and touch voltage durations in
various environmental situations.
Determination of limits needs to be based on risk assessment. Factors that are part of risk
assessment include voltage threshold values (taking into account contact area, skin moisture
condition, body current pathway) provided by this technical report, as well as other factors not
covered such as:
– reduction of the likelihood of contact (by obstacles, barriers, warnings, placing out of
reach, training, etc.); or
– reduction of touch voltage compared to the fault voltage (such as by equipotential
bonding); or
– additional resistance in series with the human body (such as gloves, shoes, carpet, etc.).
2 Normative references
The following referenced documents are indispensable for the application 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 60050-195, International Electrotechnical Vocabulary – Part 195: Earthing and protection
against electric shock
IEC/TS 60479-1:2005, Effects of current on human beings and livestock – Part 1: General
aspects
IEC 60990, Methods of measurement of touch current and protective conductor current

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TR 60479-5 © IEC:2007 – 9 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
touch current
electric current passing through a human body or through an animal body when it touches one
or more accessible parts of an installation or of equipment
[IEV-195-05-21]
3.2
touch voltage
voltage between conductive parts when touched simultaneously by a person or an animal
[IEV 195-05-11]
NOTE The touch voltage may be different from the open-circuit voltage between those conductive parts.
3.3
threshold
level of stimulus just strong enough to produce a response
NOTE A threshold is not the same as a limit which includes risk assessment, safety margins, etc.
3.3.1
voltage threshold for startle reaction
minimum derived value of touch voltage for a population for which a current flowing through
the body is just enough to cause involuntary muscular contraction to the person through which
it is flowing
3.3.2
voltage threshold for strong muscular reaction
minimum derived value of touch voltage for a population for which a current flowing through
the body is just enough to cause involuntary contraction of a muscle, such as inability to let-
go from an electrode (a.c.), but
...