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Presented by:Mick Maytum
ICT Protection Expertictsp-essays.info
Shocking Electricity
Introduction
IEC 62368-1 defines a class 2 hazard as painful on the body, but not an injury. In IEC 60749 series (Effects of current on human beings and livestock) terms a class 2 hazard can be related to the electric shock condition c1, which is a conservative body current and duration estimate below which the likelihood of ventricular fibrillation is very low. This presentation uses the IEC 60479 data for c1 and human body resistance and calculates the electrical limits of various situations.
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Topics
• IEC 60479 Effects of current on human beings and livestock series
• Body current flows• Body current-time curve• Body resistance• Hand to hand and hand to foot differences• c1 boundary line data • Multiple current pulses
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IEC 60479
• IEC TS 60479-1:2005 Effects of current on human beings and livestock -Part 1: General aspects
• IEC TS 60479-2:2007 Effects of current on human beings and livestock -Part 2: Special aspects
• IEC TR 60479-3:1998 Effects of current on human beings and livestock -Part 3: Effects of currents passing through the body of livestock
• IEC TR 60479-4:2011 Effects of current on human beings and livestock -Part 4: Effects of lightning strokes
• IEC TR 60479-5:2007 Effects of current on human beings and livestock -Part 5: Touch voltage threshold values for physiological effects
Maintained by TC 64: Electrical installations and protection against electric shockTS = Technical Specification (insufficient consensus ), TR = Technical Report (informative)
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Body currents
Body current flow hand to footBody current flow hand to hand
IH-H IH-F
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Current duration boundary
c1 current pulse for large area hand to foot contactComposite curve formed from IEC 60479-1, Figure 22 and IEC 60479-2, Figure 22
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Duration t1 - ms
0.1 1 10 100 1000 10000
c 1 b
oun
dar
y cu
rren
t (m
A)
10
100
1000
10000
Charge duration boundary
c1 current pulse charge for large area hand to foot contactFor capacitive discharge the fastest discharge time should be used (lowest body
resistance value, Pulse duration = 3RC and c1 current = peak current/2.45)
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Duration t1 - ms
0.1 1 10 100 1000 10000
c 1 c
ha
rge
- m
C
0.1
1
10
100
1000
Body resistance for large area hand to hand contact
Hand to hand body resistance versus voltageIEC 60479-1, Table 10: total body resistances for a d.c. path hand to hand,
large dry surface contact areas2/22/2017 Shocking Electricity 8
Voltage UC - V
30 40 60 80 150 200 300 400 600 800 1500100 1000
Bo
dy r
esi
sta
nce
RT -
500
600700800900
2000
3000
4000
5000
6000700080009000
1000
10000
5 % of population95 % of population
Large area hand to hand contact
Ventricular fibrillation thresholds for large area hand to hand contact. According to IEC 60479-1 the hand to hand values, relative to the hand to foot values should be adjusted as follows:• Heart factor; the hand to hand resistance is 1.4x to 1.1x
of the hand to foot resistance (a factor of 1.25x is normally used).
• The hand to hand c1 current level is 2.5x the hand to foot current level.
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c1 boundary line data (hand to hand)
c1 boundary electrical parameters for large contact area and hand to hand contact
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Duration ti - ms
0.1 1 10 100 1000 10000
c 1 b
ou
nda
ry C
urr
ent
(m
A),
an
d V
olta
ge (
V)
10
100
1000
10000
Cha
rge
(m
C)
1
10
100
1000
c1 current - mA c1 charge - mC c1 voltage - V
c1 boundary line data (hand to foot)
c1 boundary electrical parameters for large contact area and hand to foot contact
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Duration ti - ms
0.1 1 10 100 1000 10000
c1 b
ound
ary
Cu
rre
nt (
mA
),
and
Vo
ltage
(V
)
10
100
1000
10000
Cha
rge
(m
C)
1
10
100
1000
c1 current - mA c1 charge - mC c1 voltage - V
IEC TS 60479-2 multiple pulses of current
Pulse separation > 300 msPulses do not have cumulative effects on the heart and can be as single, non-repetitive pulses of current.Pulse separation < 300 msPulses have cumulative effects on the heart and the weighted cumulative value of the pulse train needs to be evaluated.
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