AS/NZS 60479.1:2002

1 - AS/NZS 60479.1:2002 EFFECTS OF CURRENT ON HUMAN BEINGS AND LIVESTOCK - GENERAL ASPECTS
4 - PREFACE
5 - CONTENTS
6 - INTRODUCTION
7 - 1 General
7 - 1.1 Scope and object
8 - 1.2 Normative reference
8 - 1.3 Definitions
8 - 1.3.1 Electrical impedance of the human body
8 - 1.3.2 Effects of sinusoidal alternating current in the range 15 Hz to 100 Hz
9 - 1.3.3 Effects of direct current
9 - 2 Electrical impedance of the human body
9 - 2.1 Internal impedance of the human body
10 - 2.2 Impedance of the skin
10 - 2.3 Total impedance of the human body
10 - 2.4 Initial resistance of the human body
10 - 2.5 Values of the total impedance of the human body
10 - 2.5.1 Sinusoidal alternating current 50/60 Hz
11 - 2.5.2 Sinusoidal alternating current with frequencies up to 20 kHz
12 - 2.5.3 Direct current
12 - 2.5.4 Effects of current on the skin
13 - 2.6 Value of the initial resistance of the human body
13 - 2.7 Dependence of body impedances on the surface area of contact for a.c. 50/60 Hz and for d.c.
21 - 3 Effects of sinusoidal alternating current in the range of 15 Hz to 100 Hz
21 - 3.1 Threshold of perception and threshold of reaction
21 - 3.2 Threshold of let-go
21 - 3.3 Threshold of ventricular fibrillation
21 - 3.4 Other effects of current
22 - 3.5 Description of the time/current zones (see figure 14)
23 - 3.6 Application of heart-current factor (F)
26 - 4 Effects of direct current
26 - 4.1 Threshold of perception and threshold of reaction
26 - 4.2 Threshold of let-go
26 - 4.3 Threshold of ventricular fibrillation
26 - 4.4 Other effects of current
27 - 4.5 Description of the time/current zones (see figure 15)
29 - Annexes
29 - Introduction
30 - Annex A - Measurements made on living and dead human beings and the statistical analysis of the results
31 - Annex B - Influence of frequency on the total body impedance (Z T )
32 - Annex C - Total body resistance (RT) for direct current
33 - Annex D - Measurements of the dependence of the total impedance of the human body (ZT) on the surface area of contact
34 - Annex E - Bibliography
36 - Annex ZA - Physiology of electrocution
36 - ZA1 Electrocution- Description
36 - ZA2 Electrical activity of excitable cells
36 - ZA3 Effect of frequency
36 - ZA4 Effect of electricity on heart muscle cells

Provides basic guidance on the general aspects of the effects of electrical currents on persons and livestock for the establishment of electrical safety requirements. This Standard has been reproduced from and is technically identical with IEC 60479-1:1994.

For a given current path through the human body, the danger to persons depends mainly on the magnitude and duration of the current flow. However, the time/current zones specified in the following clauses are, in many cases, not directly applicable in practice for designing protection against electrical shock, the necessary criterion being the admissible limit of touch voltage (i.e. the product of the current through the body and the body impedance) as a function of time. The relationship between current and voltage is not linear because the impedance of the human body varies with the touch voltage, and data on this relationship is therefore required. The different parts of the human body - such as the skin, blood, muscles, other tissues and joints - present to the electric current a certain impedance composed of resistive and capacitive components.The values of these impedances depend on a number of factors and, in particular, on the current path, on the touch voltage, the duration of the current flow, the frequency, the degree of moisture of the skin, the surface area of contact, the pressure exerted and on the temperature.The impedance values indicated in this Technical Report result from a close examination of the experimental results available from measurements carried out principally on corpses and on some living persons.Clause 3 is primarily based on the findings related to the effects of current at frequencies of 50 Hz or 60 Hz which are the most common in electrical installations. The values given are, however, deemed applicable over the frequency range from 15 Hz to 100 Hz, threshold values at the limits of this range being higher than those at 50 Hz or 60 Hz. It is considered principally the risk of ventricular fibrillation which is the main cause of fatal accidents in that range of frequencies.Accidents with direct current are much less frequent than would be expected from the number of d.c. applications, and fatal accidents occur only under very unfavourable conditions, for example, in mines. This is partly due to the fact that with direct current, the let-go of parts gripped is less difficult and that for shock durations longer than the period of the cardiac cycle, the threshold of ventricular fibrillation remains considerably higher than for alternating current.The main differences between the effects of a.c. and d.c. on the human body result from the fact that excitatory actions of the current (stimulation of nerves and muscles, induction of cardiac atrial or ventricular fibrillation) are linked to the changes of the current magnitude especially when making and breaking the current. To produce the same excitatory effects the magnitude of direct current flow of constant strength is two to four times greater than that of alternating current.

First published as part of MP 30-1976.
Revised and redesignated as AS 3859-1991.
Jointly revised and redesignated in part as AS/NZS 60479.1:2002.