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Page 14 — Property Management Quarterly — July 2017
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Maintenance
H istory tells us that in 1752
Ben Franklin flew a kite in
a lightning storm, putting
himself and his son, Wil-
liam, at grave risk of electri-
cal shock and death. And yet, Frank-
lin’s approach to this important 18th
century experiment may have been
practiced with more safety and caution
than the safety practices implemented
at modern day buildings, in regards to
their high-energy electrical panels.
Unfortunately, a vast majority of
property managers and owners are
foregoing a simple and relatively
inexpensive study to ensure that
their maintenance team is protected
from what would be the equivalent
of a lighting blast. The study, which is
often referred to as an “arc flash haz-
ard analysis” is only used by 1 percent
of property owners throughout the
Denver metro area. And while the
chances of a killer arc flash occurring
is perhaps as minute as being struck
by lighting, the risk exists. And, if left
unchecked, it could be a very costly
one.
Scientifically speaking, an electric
arc is a strong discharge of cur-
rent that jumps a gap in a circuit or
between two electrodes. Electric arc
flashes produce some of the high-
est temperatures known to occur
on Earth (some can be up to 35,000
degrees Fahrenheit, or 3.5 times the
temperature of the surface of the
sun).
The intense heat from the arc
causes the sudden expansion of air,
resulting in a blast with very strong
air pressure. All known materials are
vaporized at this temperature, and
the air blast can spread molten metal
to great distances with force.
The “fuses” that
can cause arcs
aren’t terribly
uncommon. Per-
sonnel protective
equipment should
be used while work-
ing on energized
equipment to help
eliminate arcs.
Many things can
cause these arc
flashes. For exam-
ple, dust and impu-
rities can provide
a path to allow the
current to flashover
and create arc discharge across the
surface. Fumes or vapors can reduce
the breakdown voltage of air and
cause a dangerous flash. Corrosion
of equipment can provide impurities
on insulating surfaces, also causing a
deadly flash.
Accidental contact with energized-
exposed parts can initiate catastroph-
ic arc faults, and accidental dropping
of tools may cause momentary short
circuit, producing sparks and deadly
arcs. And finally, failure of insulating
materials can cause equipment to arc
and flash.
The cost of having an arc flash haz-
ard analysis performed far outweighs
the consequences of a possible trag-
edy. A professional analysis will pro-
vide a property owner and manager
with a critical labeling system for
each and every part of their electrical
system.
The labels will define the energy
level for every piece of equipment
and the level of personnel protection
equipment required to work with or
on the specified equipment. It also
provides techniques for reducing
energy levels and putting in neces-
sary protection devices.
A thorough analysis will make it
very clear to a maintenance team
where dangerous conditions exist,
and when they should consult a pro-
fessional electrician before opening
the cover of a high-voltage electrical
panel.
For example, the labeling system
will define the following:
• Flash hazard boundaries. The dis-
tance from exposed live parts in
which a person could receive a sec-
ond-degree burn if an arc flash were
to occur.
• Flash hazard at a certain distance.
Danger levels at certain distances.
• System voltage warning. Informa-
tion that describes when there is a
potential risk of a shock hazard.
• Limited approach boundary. Unless
advised of the possible hazards and
escorted by a qualified person, no
unqualified person shall be permitted
to approach nearer than the limited
approach boundary.
• Restricted approach boundary. No
qualified person shall approach or
take a conductive object closer to
exposed energized electrical conduc-
tors or circuit parts unless the person
is insulated or guarded.
In the era of Benjamin Franklin,
safety measures such as an arc flash
hazard analysis didn’t exist. Fortu-
nately, modern day property owners
have this type of analysis at their dis-
posal and can implement it to create
a much safer working environment
for their maintenance team.s
Dennis Moyer,
PE
Electrical quality
control, MEP
Engineering Inc.,
Centennial
Arc flash hazard studies often result in a labeling system, which state warnings for
dangerous conditions for different pieces of electrical equipment.