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

IEC TR 60479-4:2020 (E) summarizes the basic parameters for lightning and its 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. The resulting effects caused by lightning currents for the organism are described.
This document shows the differences of effects on human beings and livestock due to lightning strokes versus those effects of electric shocks derived from electrical systems.
This third edition cancels and replaces the second edition published in 2011. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) lightning occurence and climatory effects around the world are depicted;
b) direct strike description is extended;
c) step voltage effects are expanded;
d) upward streamer explanation is enhanced;
e) other direct or indirect related effects to lightning injuries to the human body are specified;
f) various safety procedures and related possibilities with respect to the personsal danger of lightning are presented.

Vplivi električnega toka na ljudi in živali – 4. del: Vplivi udarov strele

General Information

Status
Published
Publication Date
12-May-2020
Current Stage
6260 - Adoption of published international/foreign standard (Local Project)
Start Date
28-Apr-2020
Due Date
03-May-2020
Completion Date
13-May-2020
Ref Project

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SLOVENSKI STANDARD
SIST-TP IEC TR 60479-4:2020
01-junij-2020
Vplivi električnega toka na ljudi in živali – 4. del: Vplivi udarov strele

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

Ta slovenski standard je istoveten z:
ICS:
13.200 Preprečevanje nesreč in Accident and disaster control
katastrof
29.020 Elektrotehnika na splošno Electrical engineering in
general
SIST-TP IEC TR 60479-4:2020

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP IEC TR 60479-4:2020
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SIST-TP IEC TR 60479-4:2020
IEC TR 60479-4
Edition 3.0 2020-02
TECHNICAL
REPORT
colour
inside
Effects of current on human beings and livestock –
Part 4: Effects of lightning strokes
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.200; 29.020 ISBN 978-2-8322-7888-8

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
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SIST-TP IEC TR 60479-4:2020
– 2 – IEC TR 60479-4:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

3.1 Definitions of technical terms .................................................................................. 7

3.2 Definitions of interactions ........................................................................................ 9

4 Basic physics of lightning ................................................................................................ 9

4.1 General ................................................................................................................... 9

4.2 Lightning occurrence ............................................................................................. 11

4.3 Lightning flash characteristics ............................................................................... 12

4.4 Primary and secondary injuries ............................................................................. 12

4.5 Summary .............................................................................................................. 13

5 Interaction of strokes with human beings and livestock .................................................. 13

5.1 General ................................................................................................................. 13

5.2 Strike mechanisms ................................................................................................ 14

5.2.1 Description of direct strike ............................................................................. 14

5.2.2 Description of contact voltage ........................................................................ 15

5.2.3 Description of side flash ................................................................................ 16

5.2.4 Description of step voltage ............................................................................ 16

5.2.4 Description of streamer current ...................................................................... 17

5.3 Specific matters regarding body response ............................................................. 19

6 Effects of lightning strokes on the body of living beings ................................................. 20

6.1 General comments on effects on the body ............................................................ 20

6.2 Comments on specific syndromes ......................................................................... 23

6.2.1 Keraunoparalysis ........................................................................................... 23

6.2.2 Burns ............................................................................................................. 23

6.2.3 Comparison between effects of electric shock derived from electrical

systems and lightning .................................................................................... 24

7 Present considerations of causation .............................................................................. 26

7.1 Under investigation ............................................................................................... 26

7.2 Electrical effects ................................................................................................... 26

7.3 Thermal, field and radiation effects ....................................................................... 26

7.4 Traumatic injury .................................................................................................... 26

7.5 Barotrauma ........................................................................................................... 27

7.6 Release of hormones ............................................................................................ 27

8 Individual and crowd safety procedures ......................................................................... 27

8.1 General – "No place outdoors is safe" ................................................................... 27

8.2 Individual actions .................................................................................................. 27

8.3 Basic principles ..................................................................................................... 27

8.3.1 General ......................................................................................................... 27

8.3.2 Individual lightning safety in the outdoors (NOAA recommendations) ............. 28

8.3.3 Safe practice indoors ..................................................................................... 28

8.4 Safety procedures for crowds ................................................................................ 29

Bibliography .......................................................................................................................... 30

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Figure 1 – Categorization of lightning types [4] ..................................................................... 10

Figure 2 – High resolution full climatology (HRFC) ................................................................ 12

Figure 3 – Direct strike.......................................................................................................... 14

Figure 4 – Direct strike with no flashover and then with flashover ......................................... 15

Figure 5 – Contact potential .................................................................................................. 15

Figure 6 – Side flash ............................................................................................................. 16

Figure 7 – Earth potential versus distance from the stroke base – 10 kA stroke, with

earth resistivity 100 Ωm ........................................................................................................ 17

Figure 8 – Examples of step voltages, assuming a uniform earth of constant resistivity,

and no surface flashover ....................................................................................................... 18

Figure 9 – Upward streamer .................................................................................................. 19

Figure 10 – Current in establishment and in collapse of upward streamer ............................. 19

Table 1 – Lightning injury and physical symptoms [8], [9], [10], [11], [12], [13], [17] .............. 22

Table 2 – Comparison of electrical and lightning injury [30], [34], [35], [40] ........................... 25

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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 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.

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 IEC technical committee

64: Electrical installations and protection against electric shock.

This third edition cancels and replaces the second edition published in 2011. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) lightning occurence and climatory effects around the world are depicted;
b) direct strike description is extended;
c) step voltage effects are expanded;
d) upward streamer explanation is enhanced;
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IEC TR 60479-4:2020 © IEC 2020 – 5 –

e) other direct or indirect related effects to lightning injuries to the human body are specified;

f) various safety procedures and related possibilities with respect to the personsal danger of

lightning are presented.
The text of this Technical Report is based on the following documents:
Draft TR Report on voting
64/2369/DTR 64/2398/RVDTR

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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 60479 series, published 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 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.
A bilingual version of this publication may be issued at a later date.

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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INTRODUCTION

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

systems on the bodies of human beings and livestock. This document describes the influence

and effect of electricity in the form of lightning strikes. Lightning current can consist of several

uni-polar and/or bi-polar impulses with different peak values and durations; IEC 60479-2:2019,

Clause 6 does not cover these effects.

The interaction of a lightning stroke with the body is often different from that of electric shock

derived from electrical systems. If the head is struck, the electrical path may include the brain

stem, which includes the respiratory centre.

IEC 60479-2 includes information related to the effects of short duration impulses which extend

to the magnitude and duration of lightning impulses.

It is accepted that more than 70 % of lightning accidents involving humans are not fatal [36],

[47] . 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 [40],[47].

It has been necessary, therefore, to create a separate document 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 ongoing life consequences.
___________
Numbers 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

This part of IEC 60479 summarizes the basic parameters for lightning and its 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.

The resulting effects caused by lightning currents for the organism are described.

This document shows 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 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 60479-1, 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 60479-1 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Definitions of technical terms
3.1.1
lightning flash

electrical discharge of atmospheric origin between cloud and earth consisting of one

or more lightning strokes
3.1.2
lightning stroke
lightning impulse
single electrical discharge in a lightning flash to earth
3.1.3
lightning channel
conducting path of the lightning current
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3.1.4
stepped leader

faintly luminous channel of generally less than 10 C of charge with associated branches that

develops in virgin air and progresses towards the earth in discrete steps
3.1.5
return stroke

bright highly visible channel carrying the impulse current of the stroke, which is initiated when

the stepped leader and upward connecting streamers meet to form the channel
3.1.6
upward flash
lightning flash initiated by an upward leader from earth to cloud
3.1.7
continuing current

current with a magnitude of tens to hundreds of amperes and a duration up to hundreds of

milliseconds often following a return stroke

Note 1 to entry Continuing currents with duration in excess of 40 ms are traditionally termed "long continuing

currents".
3.1.8
lightning current
current flowing at the point of strike
3.1.9
current peak value
maximum value of the lightning current
3.1.10
upward streamer

pre-discharge phenomena induced by the stepped leader, one of which will connect with the

stepped leader opening a lightning channel which becomes a lightning stroke
3.1.11
average steepness of impulse current

average rate of change of lightning current within a time interval bounded by the 10 % and 90 %

values of the peak impulse current front
3.1.12
stroke duration

time in microseconds between the time the return stroke exceeds 2 kA and the time to half peak

value on the tail of the current pulse
3.1.13
flash duration
time for which the lightning current flows at the point(s) of attachment
3.1.14
point(s) of attachment
point(s) at which the successful upward streamer was launched
EXAMPLE Object, human or otherwise.
3.1.15
remote earth
ideal earth of zero resistance and zero potential
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3.1.16
physical earth
earth as contact by objects

Note 1 to entry The difference between remote earth and physical earth allows the modelling of an earth resistance

between the two, creating ground potential.
3.1.17
lightning ground flash density

measurement of the number of lightning strikes to ground, over a period of one year, per km

3.2 Definitions of interactions
3.2.1
direct strike

interaction whereby the lightning attaches directly to an object (including a living object)

3.2.2
contact voltage

potential difference between contacted points on an object, on which currents generated by a

lightning event are present, or between an accessible point and an independent object

(including earth) which could result in current flow through a living being

Note 1 to entry In some texts this has been referred to as "contact potential" or "touch voltage".

3.2.3
side flash

electric arc between two objects (including living objects), at least one of which is subject to

partial lightning current
3.2.4
step voltage
step potential

potential difference between two points on the earth’s surface due to a lightning stroke current

being conducted through the earth
3.2.5
flashover

electric arc over the surface of an object carrying a significant proportion of the stroke current

3.2.6
streamer current

current, passing through an object, to establish an upward streamer, but which ultimately will

not become a point of attachment
4 Basic physics of lightning
4.1 General

The explanation of the basic physical mechanisms for the onset and the dynamics of lightning

is very complicated. Within a cloud, three layers are recognized, each with identifiable charges

(see Figure 1). They are generated by microscopic charge transfer between soft hail particles

(also called graupel) and ice crystals. The basal layer is normally negatively charged, with the

layers successively positively and negatively charged in ascending order.

Lightning is a transient, high-current discharge whose path length is measured in kilometres. A

lightning flash is a current phenomenon, and not a voltage phenomenon. More correctly, it is a

"charge dumping" phenomenon, which occurs when the increasing electric field between two

statically charged points exceeds a threshold.
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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, damage to structures and installed

equipment, and the ignition of forest fires). Cloud-to-cloud and cloud-to-air discharges have

begun to be quantified more easily as a result of space and high altitude experimentation.

Upward flashes from a cloud to the ionosphere have also been identified. All discharges other

than those between cloud and ground (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, and

less than 10 % of lightning discharges are initiated by a downward-moving positive leader [57].

Ground-to-cloud discharges are initiated by leaders that move upward from the earth. These

upward-initiated flashes are relatively rare and usually occur from mountain peaks and tall man-

made structures [56], [59].

Other important physical parameters of the lightning environment have been characterized.

Examples are the peak current per return stroke, the charge transferred in a return stroke, the

average steepness of impulse current rise, as well as the stroke duration and total flash duration

where there is more than one stroke in a flash.
a) Downward negative lightning b) Upward negative lightning
c) Downward positive lightning d) Upward positive lightning
Figure 1 – Categorization of lightning types [4]

Thunder accompanies lightning and is generated by superheated air at the channel, which

causes air pressure waves.
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4.2 Lightning occurrence

Lightning ground flash density data is now available for most world locations. Lightning location

system networks meeting the requirements of IEC 62858 [64] can provide lightning density

information with a median location accuracy for cloud-to-ground strokes better than 500 m

within the interior of the network. It is acknowledged that the data provided by lightning location

networks could underestimate the actual flash density due to multiple earth attachment points

for one-third to one-half of all cloud-to-ground flashes. IEC 62858 has introduced the term N

to identify the number of ground-strike points to represent the effect of the multiple earth

attachment points. It is generally agreed that ground strike density is the most important

parameter in assessing the number of dangerous events per year when conducting a lightning

risk assessment. It is accepted by the scientific community that the location networks more

accurately estimate the occurrence of cloud-to-ground lightning density than empirical

occurrence estimates.

Where lightning location network data is not available, the use of satellite data may be used.

These data represent the most accurate estimations available at the present time. In the past,

empirical relations were derived from an observation of thunderdays, as follows:
13, −2 −1
N = 0,T023 km yr
found best in South Africa but with wide variation [4];
14, −2 −1
N = 0,01 T km yr
-2 -1 -2 -1

found in a survey of 26 countries with N varying from 0,2 km yr to 3,0 km yr and T

G D
-1 -1
varying from 10 days yr to 100 days yr [42];
Prentice [46] recognized that the general form of these empirical equations was
b −21−
N = aT km yr

It seems empirically justifiable that b ≥ 1, since it is intuitive that the higher the number of

thunderdays, the longer one might expect a storm to last at a given location.

While the use of the thunderday has had substantial currency in the manner shown, the use of

this parameter is no longer current and should not be used in favour of LLS or satellite data.

A thunderday world map is shown in Figure 2.
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SOURCE: https://ghrc.nsstc.nasa.gov/pub/lis/climatology/LIS-OTD/HRFC/browse/HRFC_COM_FR_V2.3.2015.png

Figure 2 – High resolution full climatology (HRFC)

NOTE In most areas of the world, an indication of lightning activity can be obtained from observations of lightning

optical transients. Satellite-based sensors respond to all types of lightning with relatively uniform coverage. With

sufficient averaging, optical transient density data provide better estimates of ground flash density than thunder

observations, which have a wide range of relations between ground flash density and thunderstorm hours or

thunderstorm days. There are also regional variations in the ratio of ground flashes (CG) to total flashes (CG + IC).

The ratio of cloud flashes (N ) and ground flashes (N ) has been further estimated, and is a

c G

function of latitude. The measurement has been enhanced by the ability to differentiate cloud

and ground flashes electronically [42].
The relationship is found to be:
4,,16+ 2 16cos 3λ
( )

where λ is the latitude (in degrees). The maximum occurs at the equator and decreases with

distance from the equator.
4.3 Lightning flash characteristics

Numerous studies have determined typical values for lightning parameters. Uman and Krider

[57], and Cooray [31] provide one summary of these. The studies are also summarized in the

lightning environment defined in IEC 62305-1:2010, Tables 3 to 5, Table A.1, and Table A.3

[63]. CIGRE Technical Bulletin 549 [65] has conducted a review of recent studies and confirmed

the lightning environment of IEC 62305-1.
4.4 Primary and secondary injuries

The focus of this document is on death and injury to humans and livestock from the various

effects of lightning. Clause 5 will indicate the mechanisms by which lightning derived current

can impinge on a victim, and Clause 6 will indicate a number of the likely symptoms of injury

seen as a consequence. These are purely due to the electric current and may be thought of as

primary lightning injuries.

Another group of injuries may however be seen and are regarded as secondary to a lightning

strike. This occurs when a lightning strike damages a nearby inanimate object, and the damage

inflicted on these then causes consequent injury to a human being. Protection of structures

from examples of possible secondary injury follows. The means of protection of inanimate

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objects, including electronic equipment, is a wide science and is examined in detail in

IEC 62305 (all parts) [62].

Rocket triggered lightning experiments provide an experimental vehicle for examining these.

Their experiments are represented in the following:

• Overhead power distribution line damage, where overhead power lines become conduits for

impulses to be transmitted inside a building. Fires may result, and equipment damage may

be seen. Secondary burns and trauma may result.

• Direct strike damage: Mechanical destruction of inanimate objects may cause trauma from

fragmentation and “missiles” thrown
...

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