Electrician Brisbane Southside can undertake as small a job as installing a ceiling fan in your home to providing all the electrical services needed for a new commercial or residential build. In the late 1880s, a young boy was electrocuted when he accidentally touched an unlabeled, energized telegraph wire. That incident ignited an inventor by the name of Harold Pitney Brown to make an impassioned plea in a New York Post editorial to limit telegraph transmissions to what he considered a safer level of 300 Volts.
Perhaps Harold thought
that limiting electrical transmissions to levels of 300 Volts or less
would provide instant electrical safety. With over 120 years of
hindsight, we view things much differently today. Yet, Harold stumbled
across two important concepts. The notion of “300 Volts” is a technical
discussion about the laws of electrical energy (Ohm’s Law, etc) that
lends understanding to how electrical energy can kill or maim. On the
other hand, the term “safe” reflects a working knowledge of the
fundamental principles of safety. Our challenge is to combine our
technical understanding of electricity with the principles of safety to
ensure electrical safety is both practical and effective. The better we
understand both concepts the greater the likelihood we will have to
improve the status quo. The Risk Control Hierarchy (RCH) does an
excellent job in blending these two key concepts.
Risk Control Hierarchy
The
heartbeat of safety is the Risk Control Hierarchy (RCH), which is found
in Appendix G of the ANSI Z10 Standard. The RCH helps us prioritize
safety initiatives from least effective to most effective. For example,
will you be safer wearing a helmet while riding a motorcycle or by
selling it altogether? Obviously, selling the motorcycle eliminates the
risk of an accident, while wearing a helmet offers protection to your
head from the risk of a head injury during an accident. The RCH works by
helping us rank risk reduction measures from most effective to least
effective as per below:
1.) Eliminating the risk.
2.) Substituting a lesser risk.
3.) Engineering around risk.
4.) Awareness of every risk.
5.) Administrate and regulate behavior around risk.
6.) Protect workers while exposed to risk.
Note that each step
above is equally important, yet not equally effective in protecting
workers. Eliminating a risk is the most effective way to keep workers
safe while protection from a risk by using Personal Protection Equipment
(PPE) is least effective. There have been great improvements in the
design of PPE, but its primary purpose is keeping workers alive – not
100% safe.
Safety and Risk
Risk, which is defined as
exposure to a hazard, is two-pronged. There is the probability of
exposure and severity of potential injury. For example, a 120V outlet is
a greater risk than a 13.8KV switchgear line-up because more people are
exposed to the 120V outlet. Since risk is exposure to hazards, then
safety is the reduction and management of risk. The management
responsibility of an electrical safety program typically falls to an
electrical engineer because he or she understands electricity. In our
modern world we can never eliminate the risk, but are very good at
finding new ways to reduce risk.
Another way to look at risk is
the chart (Figure 2) developed by Ray Jones which shows the relationship
between the worker and the safety infrastructure above him. A worker
performing tasks must make many complex and specific the decisions that
affect his safety. In the case of electrical safety, energy isolation is
very personal for electricians facing deadly electrical energy every
time they open a panel. By the time they touch electricity, it’s too
late.
Zero Energy Verification–Is There Voltage?
Electrical
accidents are impossible without electrical energy. If an electrician
comes into direct contact with electrical energy, there is a 5% fatality
rate. Shocks and burns comprise the remaining 95%. The NFPA 70e is very
specific on how to isolate electrical energy. First, all voltage
sources must be located and labeled. Multiple voltage sources are
commonplace today due to the proliferation of back-up generators and
UPS’s. Next, voltage testing devices must be validated using the
LIVE-DEAD-LIVE procedure. Additionally, the voltage tester must also
physically contact the voltage and must verify each phase voltage to
ground.
The RCH and Electrical Safety
How does the RCH apply to electrical safety?
1. Elimination -Removing all electrical energy exposure.
2. Substitution -Lowering the electrical energy exposure.
3. Engineering Controls -Reinventing ways to control electrical energy exposure.
4. Awareness -Revealing and labeling all sources of electrical energy.
5. Administrative Controls -Regulations that teach personnel safety around electrical energy.
6. Personal Protection -Reducing risks of working on live voltage.
Electrical
workers are exposed to the greatest risks at the lower levels of the
RCH. Recognizing that these ‘residual risks’ are present; the NFPA 70e
tells workers how to perform their work safely in spite of these risks.
In fact a large portion of the NFPA 70e details how to best manage these
risks through Awareness, Administration, and Personal Protection. On
the other hand, the greatest opportunity for risk reduction comes by
focusing in the upper part of the RCH. Huge improvements in electrical
safety will come by Eliminating Substituting, and Engineering solutions
that manage electrical energy exposure.
The Department of Energy (DOE)
For better insight into the RCH
process, let’s look at a 2005 Department of Energy report on their
electrical safety record. This report cited six reasons for their 14.1
electrical incidents per month.
Within this DOE report, “hazard identification” [Table 1] stood out
as an administrative control issue resulting in numerous electrical
incidents. The solution was to get tougher administrators or look for
improvements higher up in the RCH. Right above Administrative Controls
(see Figure 1) we learn that increasing employee’s awareness of
electrical hazards will reduce these types of incidents. A potential
solution is to label and mark all voltage sources (hazards) feeding the
electrical system. Voltage indicators and voltage portals wired to each
voltage source provides two benefits: It identifies the voltage source
and provides a means to check the status of that voltage source without
exposure to voltage. Apply the same process to “LO/TO violations”.
CAUSES OF INCIDENTS PRESENT RCH PRINCIPLE INCREASED RISK REDUCTION RCH PRINCIPLE Lack of hazard identification.
ADMINISTRATIVE
Properly administrating NFPA 70e requires all electrical enclosures to
have warning labels with incident energy level (calories). AWARENESS
/ELIMINATION Marking all energy sources on the panel exterior provides
personnel with simple yet safe hazard identification.
LO/TO violations including shortcuts or lack of energy verification
ADMINISTRATIVE Can the LO/TO procedure be rewritten to reduce exposure to voltage?
ELIMINATION
/SUBSTITUTION Thru-door voltage pre-checking ‘eliminates’ all exposure
to voltage for mechanical LO/TO* and provide significant risk reduction
for Electrical LO/TO.
Reducing electrical energy to Cat 0/1 will
greatly reduce the potential arc flash energy SUBSTITUTION Lowering the
arc flash energy effectively ‘substitutes’ for a lower risk for a higher
risk.
Elimination: The Hall of Fame of Safety
We can enter
the Electrical Safety Hall of Fame by finding ways to eliminate voltage
exposure. Here are a few practical examples that can be implemented
today:
o Mechanical Lock-out Tag-out [LOTO]: LOTO procedures requiring
electricians to verify zero energy before performing mechanical
maintenance needlessly exposes workers to voltage. Since all voltages do
not create mechanical motion, through-door voltage checking devices as
part of a mechanical LOTO procedure will eliminate voltage exposure (see
Appendix B).
o Why open a control panel? What maintenance functions can be moved
to the outside of the panel? Thru-door data access ports are becoming
commonplace because they allow programming with the panel door closed
(Figure 3). A more recent example is an unmanaged Ethernet switch
mounted outside the panel. This unique device allows full through-door
access for a worker to troubleshoot and reset the Ethernet switch
(Figure 4). What other devices can be re-engineered around through-door
electrical safety? Perhaps putting certain branch circuit breakers on
the outside of the panel is a good application?
o Control Panel Design: Provide a physical separation between the
power and control compartments within an enclosure may become a
standard. Voltages under 50 volts are considered safe, so reducing the
control power to 24VDC makes the control power section safe to work on
while it is energized.
These above examples are only ‘scratching the surface’, so I challenge you to find ways to eliminate voltage exposure.
Conclusion
When safety works perfectly, nothing happens! When there is an incident or a close call the RCH should be an inspiration to find a better way. By applying the RCH principles to electrical safety risks, it will open our eyes to see more practical ways to reduce those risks. Perhaps, we would expend more resources finding electrical safety solutions that will provide both higher safety and productivity dividends.
Harold Pitney Brown intuitively knew that eliminating risks would save lives. He just got one detail wrong when he thought that 300 Volts was not a risk. Now for the rest of the story: To prove that AC voltage is more lethal than DC, Thomas Edison hired Harold Pitney Brown to develop the first electric chair that executed William Kemmler on August 6, 1890. So much for electrical safety!
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