by Gerard Fonte
In The Trenches
The Business of Electronics Through Practical Design and Lessons Learned
In The Trenches
Safety and Risk
Safety is clearly an important
issue for any engineer. It covers
your own personal safety and
the safety of your customers. It also
includes your product. Is it operating
within safe limits or will it fail? Then
there is the question, "Is it safe
enough?" This is defined as risk.
Your Personal Safety
on the Job
Engineering is not an inherently
safe occupation. It is safer than many,
but there are risks. You can get
shocked or, perhaps, electrocuted.
You can burn yourself with a soldering
iron or have a serious accident with
the wave-solder machine. You can
drop a hammer on your foot or have
one fall on your head at a job site.
Fundamentally, wherever things are
made, tools are used; wherever tools
are used, accidents can happen.
For the most part, you are
responsible for your own safety. You
should know how to operate all of
your tools safely. You should know
what safety equipment is for and what
it can and cannot do. You should be
aware of dangerous situations and be
able to foresee likely problems.
Trusting someone else where
safety is concerned is not a good
thing to do. The idea that, "They
wouldn't ask me to do something
unsafe," is simply wrong. Consider
cigarette smoking, tobacco farming,
coal mining, and working with
asbestos as examples. It is true that
few companies will deliberately place
employees at risk. It is also true that
few companies will actively search
out ways to improve worker safety.
Why should they? "Things are
safe now. We don't need to waste
money on something that may never
happen." It's basic human nature to
wait until an accident occurs before
implementing safety precautions. Do
you want to be that accident?
If you think you are being asked
to do something unsafe on the job,
tell someone. Ask for proper safety
equipment. The federal government
and many states have laws for
protecting workers. You may not be
required to do something you feel is
unsafe. Check into your rights. Being
macho is also being stupid.
Most safety issues occur through
ignorance or stupidity. Yes, there is a
difference. Ignorance is a lack of
knowledge. A three-year-old who
sticks something in an electrical outlet
is ignorant. Stupidity comes from lack
of forethought. An adult who sticks a
knife in a toaster to retrieve some
bread and gets zapped is stupid. Let's
look at a couple of examples. An engineer was working on a prototype that
needed a lithium battery soldered into
the circuit. He didn't have any batteries
with solder tabs, so he tried to solder
wires directly to the body of the
battery. The battery exploded, causing
very minor injuries. The engineer
should have known better. Haven't we
all seen the warnings? "Do not dispose
of in fire. Battery may explode." He
wasn't thinking about what he was
doing; he was being stupid.
A friend was about to take
uninsulated pliers to remove pieces of
a light-bulb socket that had broken off
in a ceiling fixture. He turned off the
power switch, but not the circuit
breaker. Was he safe? After all, the
switch controls the hot lead.
No — I warned him that he was
not safe at all. First, he was trusting
that someone else had wired the
switch properly. While this is probably
true, it is not guaranteed. Second —
and much more importantly — the
light was controlled by two different
switches. This two-way switch
configuration gave him a 50% chance
of having the hot lead switched to
BOTH light bulb contacts. Surprised?
Work out the circuit for yourself and
see. This is ignorance. The wall
switch is supposed to control the hot
lead. He had no idea that different
switches were wired differently.
This is where we have to take a
slight detour into risk assessment. It's
something we do every day, but,
often, we aren't aware of it. Every
time we drive or cross a road, we
take a risk, but we also assess the
situation for safety. If the road is busy,
we're more careful. Proper risk
assessment requires the understanding of the elements of the situation.
Often, these elements are available. An
ability to assign a likelihood to an event
is also required. Generally, this is also
possible. Unfortunately, many people
(perhaps most) fail to consider the
probability of such an event occurring.
Let's look at two very similar
events: the Unabomber and the
anthrax letters of a few years ago.
Both killed or injured a similar and
relatively small number of people.
Both used the mail as their vehicle.
Both were fairly recent. Both were
(apparently) the work of domestic terrorists. However, the Unabomber had
virtually no effect on mail service or