IEC TR 60479-4:2011

IEC/TR 60479-4


®


Edition 2.0 2011-0



TECHNICAL



REPORT



RAPPORT
TECHNIQUE
colour
inside


Effects of current on human beings and livestock –
Part 4: Effects of lightning strokes

Effets du courant sur le corps humain et sur les animaux domestiques –
Partie 4: Effets de la foudre


IEC/TR 60479-4:2011

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IEC/TR 60479-4


®


Edition 2.0 2011-0



TECHNICAL



REPORT



RAPPORT
TECHNIQUE
colour
inside


Effects of current on human beings and livestock –
Part 4: Effects of lightning strokes

Effets du courant sur le corps humain et sur les animaux domestiques –
Partie 4: Effets de la foudre


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX S
ICS 13.200; 29.020 ISBN 978-2-88912-694-1

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – TR 60479-4  IEC:2011



CONTENTS

FOREWORD . 3


INTRODUCTION . 5

1 Scope and object . 6

2 Normative references . 6


3 Terms and definitions . 6

4 Physics of lightning . 9

5 Interaction of strokes with human beings and livestock . 10

5.1 General . 10
5.2 Description of direct strike . 10
5.3 Description of contact voltage . 11
5.4 Description of side flash . 12
5.5 Description of step-voltage . 13
5.6 Description of streamer shock . 15
5.7 Description of flashover . 16
6 Effects of lightning strokes on the body of human beings and livestock . 16
6.1 General . 16
6.2 Physiological effects . 16
6.3 Pathophysiological effects . 17
6.4 Thermal effects . 17
6.5 Comparison between effects of electric shock derived from electrical
systems and lightning . 17
6.6 Percentage occurrence . 17
Bibliography . 20

Figure 1 – Categorization of lightning [4] . 10
Figure 2 – Direct stroke . 11
Figure 3 – Contact voltage . 12
Figure 4 – Side flash . 13
Figure 5 – Step voltage . 14
Figure 6 – Step voltage on quadrupeds . 14
Figure 7 – Step voltage with side flash . 15

Figure 8 – Upward streamer current . 16

Table 1 – Causes of lightning death and most typical reported consequent disorders
[11-16], [20] . 18
Table 2 – Differences between low voltage and high voltage injuries from electrical
systems, and lightning injuries [1], [11-16], [20] . 19

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TR 60479-4 © IEC:2011 – 3 –


INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________



EFFECTS OF CURRENT ON HUMAN BEINGS AND LIVESTOCK –



Part 4: Effects of lightning strokes





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 60479-4, which is a technical report, has been prepared by technical committee
No.64: Electrical installations and protection against electric shock.
This second edition cancels and replaces the first edition, published in 2004 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– the report has been completed with additional information on the influences and effects of
natural electricity in the form of lightning strokes during thunderstorms;
– the definitions and technical terms have been updated;

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– 4 – TR 60479-4 © IEC:2011


– the explanation of the basic physical mechanisms for the dynamics of lightning where

specified;

– the references to the relevant literature and the list of bibliography are updated;


– figures showing the current path during different interactions of lightning with the victim’s

body are updated.

The text of this technical report is based on the following documents:


Enquiry draft Report on voting

64/1772/DTR 64/1804/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.
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 stability 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.

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.

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TR 60479-4  IEC:2011 – 5 –


INTRODUCTION


IEC 60479-1, IEC 60479-2 and IEC 60479-3 deal with the effect of electric shock derived from

electrical systems on the bodies of human beings and livestock. This part of IEC 60479, which

is a technical report, describes the influence and effect of natural electricity in the form of

lightning strokes during thunderstorms. Lightning current can consist of several uni-polar

and/or bi-polar impulses with different peak values and durations; Clause 6 of IEC/TS 60479-

1
2:2007[24] does not cover these effects.


The interaction of a lightning stroke with the victim’s body is quite different from the usual

experience with electric shock derived from electrical systems. The pathway often includes

the head in lightning accidents. The importance of the cranial orifices as points of entry of
lightning current has been noted, and from these the proximity of the pathway to the
brainstem. The brain stem includes the respiratory centre, in contrast with pathways of shock
current arising from electrical systems. In particular it should be pointed out that differences
exist between accidents caused by a direct flash compared with those interactions which are
caused by step voltages. Even very short single impulses of lightning can cause
cardiopulmonary arrest [5], [6], [15] and [16].
The intense electric interactions with living organisms are very dangerous but, surprisingly in
many cases, not always lethal. It is accepted that more than 90 % of lightning accidents
involving humans are not fatal [1], [12]. Corresponding reliable data for livestock is not known.
There is a large variation in outcome due to different environments, different activities of
people and knowledge of first aid and quality of medical care [1], [5].
It has been necessary, therefore, to create a separate standard concerning the special effects
of lightning strokes. The physical behaviour of lightning is shown as a basis. The interaction
with a living body is then described, followed by the consequences for the life of the victim.

___________
1
 References in square brackets refer to the bibliography.

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EFFECTS OF CURRENT ON HUMAN BEINGS AND LIVESTOCK –



Part 4: Effects of lightning strokes








1 Scope and object


This part of IEC 60479, which is a technical report, summarizes the basic parameters for

lightning and their variability insofar as they apply to human beings and livestock.
The possible direct and indirect interactions of strikes with bodies of living beings are
indicated and the resulting effects caused by lightning currents for the organism are
described.
The object of this report is to show the differences of effects on human beings and livestock
due to lightning strokes versus those effects of electric shocks derived from electrical
systems.
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/TS 60479-1:2005, Effects of current on human beings and livestock – Part 1: General
aspects
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC/TS 60479-1, in
addition to the following definitions, apply.
3.1 Definitions of technical terms
3.1.1
lightning flash
atmospheric discharge consisting of one or more strokes

3.1.2
lightning stroke
single electrical discharge in a lightning flash
3.1.3
lightning channel
conducting path of the lightning current
3.1.4
stepped and connecting leader
stepped leader stepping down from a cloud and a connecting leader stepping up from points
of field concentration beneath, noting that they are low current non-luminous processes
leading to the return stroke when the two connect

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TR 60479-4  IEC:2011 – 7 –


3.1.5

main stroke

return stroke

bright lightened stroke with strong current discharge, which is initiated at that moment when

the stepped and connecting leader comes into contact with the earth


3.1.6

downward flash

lightning flash initiated by a downward leader from a cloud to earth


3.1.7

upward flash
lightning flash initiated by an upward leader from earth to cloud; that part of a stroke when the
leader grows from earth to cloud
3.1.8
continuing current
mean current of the long-lasting component of the lightning current
3.1.9
peak value of current
maximum value of the lightning current
NOTE Values are given in Table A.2 and Figure A.5 of IEC 62305-1:2010 [7].
3.1.10
flash charge
time integral of the lightning current for the entire lightning duration
NOTE This value ranges from 0,2 °C to 350 °C for the majority of positive and negative lightning strokes [7].
3.1.11
impulse charge
short stroke charge
time integral of the lightning current for the impulse part of the lightning duration
NOTE This value ranges from 0,22 °C to 150 °C for the majority of positive and negative lightning strokes [7].
3.1.12
specific energy
energy dissipated by the lightning current in a unit resistance
NOTE It is the integral of the square of the lightning current for the duration of the lightning. This value ranges

3 7
from 6 × 10 J/Ω to 1,5 × 10 J/Ω for the majority of positive and negative lightning strokes [7].
3.1.13
average steepness of current wave front
average rate of change of current calculated over 10 % to 90 % of peak amplitude of the wave
front [7]
NOTE This value ranges from 0,2 kA/µs to 99 kA/µs for the majority of positive and negative lightning strokes.
3.1.14
stroke duration
Time from the initiation of an atmospheric discharge until the time that particular stroke has
been extinguished (the range of 3.1.5) and is 15 μs to 2000 μs for the majority of positive and
negative lightning strokes [7]

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– 8 – TR 60479-4  IEC:2011


3.1.15

stroke interval

time interval between the beginnings of successive strokes


3.1.16

total flash duration

Time from the beginning the first stroke to the end of the last stroke with a time range of 0,1

ms to 1100 ms for the majority of positive and negative lightning flashes [7]


NOTE 1 Experience shows that the statistical distribution of the parameters of total flash duration as expressed
by Definition 3.1.16, can be assumed to have a logarithmic normal distribution.


NOTE 2 A flash is made up of a number of strokes. A continuing current may result and continue for some time.
The duration of the flash is therefore dependent on the stroke duration, the number of strokes of the flash and the
duration of any continuing current. All of these are variable and statistically described.
3.2 Definitions of interactions
3.2.1
direct stroke
interaction whereby the tip of the stepped and connecting leader attaches directly to the living
being (see Figure 2)
3.2.2
contact voltage
potential difference between accessible points when touched simultaneously by a living being
(see Figure 3)
NOTE In some texts this has been erroneously referred to as “contact potential” or “touch voltage”
3.2.3
side flash
electric arc between two objects, at least one of which is contacted by lightning (see Figures 4
and 7) )
3.2.4
step voltage
voltage on the earth’s surface between two points
[IEC 60050-195:1998, 195-05-12, modified] [25]
NOTE The possible resulting currents are shown in Figures 5 and 7. .
3.2.5

streamer current
current flowing through an individual as that individual serves as the starting point for an
upward streamer which ultimately does not join a stepped leader to form a conducting channel
(see Figure 8)
3.2.6
flashover
electric arc over the surface of the body carrying a significant proportion of the current
NOTE It may occur with the other combinations above (see Figure 2).
3.3 Definitions of effects on organisms
3.3.1
physiological effects
reaction due to external electrical stimulation of excitable cells, such as all kinds of skeletal
muscle, smooth muscle of arteries and veins, cardiac muscle, nerves and all the structures of
the brain

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TR 60479-4  IEC:2011 – 9 –


NOTE These effects are transient and stimulate the tissue within the limits of physiological function.


3.3.2

pathophysiological effects
stimulatory or inhibitory effects which lead to reversible or irreversible dysfunction of the

affected structures of the organism


NOTE 1 These effects are of long duration and are produced by stimuli outside usual physiological magnitudes


NOTE 2 This group of effects includes keraunoparalysis which is a transient paralysis of the muscular structures

in the line of the current. Its cause is uncertain.

3.3.3

thermal effect
pathophysiological effect of electrical current which results from local and transient heating of
the affected structures up to temperatures where parts of cells and organelles become
denatured
NOTE The effect of evaporation remains to be proved [17].
4 Physics of lightning
The explanation of the basic physical mechanisms for the onset and the dynamics of lightning
is very complicated. Recent explanation takes into account that a tripolar layered cloud is
generated by microscopic charge transfer between soft hail particles (also called graupel) and
ice crystals [3].
Lightning is a transient, high-current discharge whose path length is measured in kilometres.
Well over half of all flashes occur wholly within the cloud and are called intra-cloud (IC)
discharges. Cloud-to-ground (CG) lightning has been studied more extensively than other
forms of lightning because of its practical importance (for instance, as a cause for injuries and
death, disturbances in power and communication systems and the ignition of forest fires) and
because lightning below a cloud is more easily studied with optical techniques. Cloud-to-cloud
and cloud-to-air discharges occur less frequently than either IC or CG lightning. All
discharges other than CG are often combined under the general term "cloud discharges".
Four different types of discharges between cloud and earth have been identified (Figure 1).
Negative CG flashes probably account for about 90 % of the CG discharges world-wide
(Figure 1a), and less than 10 % of lightning discharges are initiated by a downward-moving
positive leader (Figure 1c) [4]. Ground-to-cloud discharges are initiated by leaders that move
upward from the earth (Figurse 1b et 1d). These upward-initiated flashes are relatively rare
and usually occur from mountain peaks and tall man-made structures [3].

Other important physical parameters are the specific energy per stroke, the average
steepness of current rise within a stroke, as well as the stroke duration and total flash
duration where there is more than one stroke in a flash.
The mechanical effects are related to the peak value of the current and specific energy. The
thermal effects are related to the specific energy when resistive coupling is involved and to
the total charge or impulse charge when arcs develop. The highest peak values, specific
energy and impulse energy occur in positive lightning strokes.
The inductive coupling is related to the steepness of the lightning current front. The highest
value of this parameter occurs in subsequent negative strokes [5].
Thunder accompanies lightning and is generated by super-heated air at the channel, which
causes air pressure waves.

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– 10 – TR 60479-4  IEC:2011














IEC  2073/11 IEC  2074/11

Figure 1a – Lightning begins with Figure 1b – Lightning has a positively charged
a negative charged leader leader, and hence this type effectively
moving downwards lowers negative charge to earth
IEC  2076/11
IEC  2075/11


Figure 1c – Discharges are initiated by Figure 1d – The leader is charged negatively
a downward moving positive leader and effectively lowers positive charge
(reprinted from [4])
Figure 1 – Categorization of lightning [4]
5 Interaction of strokes with human beings and livestock
5.1 General
The possible interaction of lightning with human beings and livestock depends on the resulting
time course and pathway of the current in the body and on its surface. As the temporal and

spatial current distribution of strokes varies, so the effects on living organisms are different.
The effects of magnetic fields derived from the lighting stroke upon a living organism are not
thought to be significant [23].
5.2 Description of direct strike
When the tip of the downward stepped leader has reached a height of some tens of metres
above ground level, the resulting field strength attains a critical value so that a short upward
streamer can be initiated from a conductive object or victim. The flow of current of the whole
discharge goes direct via the victim’s body (Figure 2).
A description of direct lightning stroke interaction is given in 5.6.

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TR 60479-4  IEC:2011 – 11 –











i
B

i
s


IEC  989/04


Key
i body current
B
i surface flashover current
s
Figure 2 – Direct stroke
5.3 Description of contact voltage
When an object, not necessarily metallic, is struck by lightning, points on its surface are
raised in potential. When a person contacts one of these points and another, possibly earth,
to complete a circuit, partial lightning current will flow through that person. This contact
voltage is determined
...