Electrocutions & Risk
A regulators perspective (Coal Mine Focus)
Mining Electrical & Mining Mechanical Engineers Society April 2013
Electrocutions & Risk
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

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Dangers of electricity
Electrocutions in NSW and Australian society
Risk acceptance and electrocution
Preventing electrocutions in NSW
Coal industry risk acceptance
Electrocutions in NSW coal mines
Preventing electrocutions in NSW coal mines
Conclusions
Electricity kills
Stop electricity killing
Electrocutions in NSW & Australia
Number of electrocutions
35
30
25
20
15
10
5
09
07
20
08
/
05
20
06
/
03
20
04
/
01
20
02
/
99
20
00
/
97
19
98
/
95
19
96
/
93
19
94
/
91
19
92
/
89
19
90
/
87
19
88
/
85
19
86
/
83
19
84
/
19
82
/
19
80
/
81
0
Electrocutions in NSW have declined steadily since 1955
 Approx 0.8/year per million population - average 2000-2011
Electrocutions in Australia
 Approx 0.9/year per million population – average 2000-2011
 Approx 1/year per million workers – average 2008-2011
Is the risk of electrocution
acceptable ?
 Individual risk (IRPA)?
 Societal risk?
 Acceptable = Tolerable & ALARP?
 Acceptable = Broadly acceptable (HSE) = negligible?
 Acceptable is a moving target
– In a risk averse society the level of risk acceptance is reducing
– Acceptable is about not doing anything to change the status quo
 The risk of electrocution in NSW IS NOT acceptable
Is the risk of electrocution
tolerable ?
 Tolerable¹:
1. satisfactory but not very good.
2. if something is tolerable you are able to accept or deal
with it, although you do not like it.
 The risk to an individual (IRPA) of electrocution in NSW IS
tolerable
 Although we tolerate, we don’t like it
¹ MacMillan Dictionary
The risk of electrocution tolerable,
HOWEVER
 Society expects that all reasonably practicable
measures are taken to prevent electrocution
 Tolerable risk = adequate control²
 Tolerable risk is about control effectiveness²
² “Classic failure modes of operational risk management”, Joy, J., EESS
Nov 2012
Preventing electrocution in NSW
 Electricity distribution is:
– specifically regulated
– done to set standards (safety and compatibility)
– done by highly competent organisations
 Specific consumer electricity safety legislation that requires:
– Electrical installations to a set standard (AS/NZS3000)
– Electrical installations done by competent people (licensed
electricians)
– Electrical installations verified to a set standard
– Appliances constructed and verified to a set standard
 General workplace OHS legislation.
Tolerable risk and the NSW coal
industry
 We want to reduce risk
 To reduce risk = more controls or more
effective controls or both
 In reality we strive for tolerable and ALARP
risk and hope this realises the vision of zero
harm.
Electrocutions in the NSW coal
industry
1977 – U/G – Adjusting an energised 11kV CB
1982 – O/C - contact with 11kV whilst climbing a
pole to work on a Tx in a switch yard.
IRPA of electrocution in a NSW coal mine:
> NSW community level < 3X10-6
Preventing electrocution in mines

Mines are subject to the requirements of NSPs

Implementation of known electrical engineering
• Live conductors – kept out of reach
• Earthing
• Earth fault limited systems
• Multiple levels of electrical protection
• Electrically rated equipment (constructed and verified to a set standard)
• Environmentally rated equipment (constructed and verified to a set standard)
• Electrical installations (installed and verified to a set standard by competent
people)

Implementation of known good electrical practices
• No live line work
• Test before you touch

Electrical engineering controlled by electrical engineers
Electric shocks 1999 – 2012
(Total = 370)
 LV = 294
 HV =17
 Welding = 42
 Static, ELV & lightning = 17
Electric shocks above ELV
40
35
30
25
TOTAL
U/G COAL
O/C COAL
20
15
10
5
0
99- 00- 01- 02- 03- 04- 05- 06- 07- 08- 09- 10- 1100 01 02 03 04 05 06 07 08 09 10 11 12
LV Electric Shock
 Surface (216)
– Not FFP = 77%
– Ingress = 39%
 U/G (74)
– Not FFP = 77%
– Ingress = 51%
 Unknown (4)
LV Electric Shocks
 Surface
– Direct contact = 32%
– Indirect contact = 67%
– Non-electrical work =
72%
 U/G
– Direct contact = 28%
– Indirect contact = 72%
– Non-electrical work =
75%
LV Electric Shocks
 Surface
– Procedural = 24%
 U/G
– Procedural = 19%
Preventing electrocution
 Eliminating direct contact can reduce shocks by up
to 31%:
– Isolate and test for dead – basic electrical
practices
– Operational RA for specific circumstances
– High rigour is required as there is often no
engineered mitigation
Preventing electrocution
 Maintaining IP ratings can reduce shocks by up to
42%.
– This is an indirect contact electric shock
– Basic electrical engineering of rating equipment
– Technical RA for specific circumstances
 Back up engineering reduces the risk of
electrocution due to failed IP.
– earthing,
– earth fault limitation
– electrical protection
Preventing electrocution
 ELV control circuit devices can reduce shocks by
up to 19%
– Mining electrical engineering practice
– Technical RA for specific circumstances
 240V tools, appliances and leads account for 15%
of LV shocks.
– Battery powered tools
– Operational RA where battery power is not
useable
Preventing electrocution through
engineering
 Engineering risk controls for preventing electric shock:
– are based on good and reliable electrical engineering,
– are well known,
– often documented in standards (IEC and AS/NZS)
 Electrical procedural risk controls
– are based on established good electrical work practices,
– are well known,
– often documented in standards (IEC and AS/NZS)
Preventing electrocution & Risk
Assessments
 Technical RA’s - selecting risk control options
 Technical RA’s - determining risk control reliability
 Operational RA’s - for unique installations, tasks
and circumstances.
 Other risk assessment techniques are applicable
for risk control review (eg “Bow Tie”)
Conclusions

The risk of an individual being electrocuted is NOT acceptable

The risk of an individual being electrocuted is tolerable

This is achieved by
– Application of known electrical engineering
– Application of established electrical work practices
• No live line work
• Test before you touch
– Verification by competent and recognised practioners
– Specific electrical legislation
– Integrating RA (where necessary) in the electrical engineering and work
practices
– Synergy of the above
Conclusions
Preventing electrocutions
 Known hazard
 Known risk controls
 No brainer
– Implement the known electrical engineering
– No live line work
– Test before you touch
 RA can support the above
 GOOD ELECTRICAL ENGINEERING DELIVERS THE
GREATEST RISK REDUCTION