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Safety
ARC FLASH AWARENESS & AVOIDANCE

How to Reduce Exposure to a Hair-raising Electrical Hazard

BY MIKE LANE, NSAA DIRECTOR OF TECHNICAL SERVICES

IN THE CHAIRLIFT COMMUNITY you tend to hear a lot of inter-
esting stories, like the one about a talented lift electrician
(let’s call him “Dave”) whose reader glasses nearly melted
on his face as the result of some admittedly bad decisions
he made while trying to reroute a small ground wire. Dave
ended up with second- and third-degree burns on his hands,
a “rejuvenating” face peel, and a weekend stay at the ICU—
all because of a potentially deadly electrical explosion known
as “arc flash.”
Stories like this are alarming but not particularly surpris-
ing, given the fact that lift operations essentially are a
confluence of metal, physics, electricity, and the people who
control, maintain, and monitor these elements. As many
electricians do every day, Dave was working with live equip-
ment on a simple, small project, but he made a few missteps
that could have cost him his life.
The fact is, all high-voltage power panel/distributions
have the potential to generate arc flash, the single most Causes of Arc Flash
dangerous cause of serious injury and potential fatality in the
maintenance of electrical power distribution system equip- • Lack of electrical safety awareness and training
ment. A simple way to describe arc flash is to draw a compar- • Carelessness or accidents, e.g., touching the wrong
ison to an electric arc—the luminous white bridge formed in surface with a test probe
the gap between two electrodes. Remember when you used • Improper tools, installation, and work techniques
to brush your feet along the carpet in wool socks and shock • Use of damaged electrical materials/equipment
your sister? Arc flash is like that, but on steroids. • Obstruction in disconnect panels
This electrical phenomenon can be caused by a number • Insulation damage, gaps, or wear and tear
of factors (see “Causes of Arc Flash”), but it usually involves • Dust, debris, and corrosion on electrical conductors
a low impedance connection to the ground. Not to get too • Improper preventative maintenance for circuit breakers
technical, but an electrical impedance is the measure of the and switches
opposition that a circuit presents to a current when a voltage • Exposed live parts, loose connections, or corrosion
is applied. In other words it occurs during a fault or short • Static electricity or high voltage cables
circuit condition that passes through this arc gap. When • Exposure of electrical equipment to water or
there is a low impedance connection in an electrical system, other liquids
an explosion occurs. That allows movement of an unwanted
electric discharge through the air from one voltage phase
to another, or to the ground, which leads to a sudden and voltage—that person is exposed to the potential for arc flash
extreme rise in temperature and pressure. One of the best and the subsequent “arc blast,” the powerful release of fire,
ways to reduce impedance is to maintain all electrical gear intense light, and pressure waves in an explosion of flying
properly, and make sure all connections are tight. shrapnel. In an instant, flash temperatures can liquefy or
Regardless of the cause, anytime someone opens a power vaporize metal in the vicinity, including copper, aluminum
panel to investigate or resolve an issue—without having conductors, and steel parts, producing explosive pressure and
first properly monitored and mitigated, if need be, the sound waves.

18 | NSAA JOURNAL | WINTER 2019