Five to ten arc flash explosions occur in electric equipment
every day in the United States, according to statistics
compiled by CapSchell, Inc. This number does not include
cases in which the victim is sent to an ordinary hospital
or clinic for medical treatment. Unreported cases and "near
misses" are estimated to be many times this number.
Instead these injuries are so severe the victims require
treatment from a special burn centre.
What is an Arc Flash?
Think of an arc flash as a short circuit through the air.
In an arc flash incident, an enormous amount of concentrated
radiant energy explodes out wards from the electrical equipment
(see video), creating pressure waves that can damage a persons
hearing, a high-intensity flash that can damage their eyesight
and a superheated ball of gas that can severely burn a workers
body and melt metal. The pressure waves can also send loose
material like pieces of damaged equipment, tools and other
objects flying through the air.
The NFPA 70E regulations define a series of boundaries
related to electrical safety when working on energized equipment.
The flash protection boundaries define the safe working
distances in which any tradesman can operate in from a energized
component. Thermographers must be fully conversant with
these regulations, as occasionally we need covers to be
removed to allow access for an inspection to be completed.
Remember ignorance
is no excuse!
Note: The NFPA 70E regulations also stipulate that
unless the thermographer is a certified electrician they
will need to be accompanied by qualified personnel.
NFPA 70E 2004 Equipment Requirements
Once a thermographer has identified the need to complete
a live inspection within a flash protection boundary, they
must then identify the level of Personal Protection Equipment
PPE that is required.
Below is the proposed equipment requirement based on the
expected Arc Flash energy level of the equipment being inspected?
Arc flash is a serious hazard that can be devastating
to those exposed to it. It can also cause lengthy downtime
to repair or replace severely damaged equipment. The requirements
of NFPA 70E help plant and facility managers to reduce the
probability of an arc flash event and its effects. This
is where the use of thermography in conjunction with infrared
windows can assist
The vast majority of arc flash incidents occur when there
is a change of state within the panel (opening the panel
doors, removing covers, etc) or through operator error (dropping
tools, touching live components, etc). Using infrared windows
means that there is no need to remove covers in order to
allow a full thermographic inspection of an electrical panel
to be completed, thus negating exposing an operator to energized
electrical components, therefore removing the major causes
of arc flash incidents.
Inspecting electrical systems during peak loading with
no interruption to process has always been the preferred
time to test an electrical system, however, due to the perceived
risks and downtime associated with traditional inspection
methods is normally the most difficult time to gain access,
thermographic inspections in conjunction with infrared windows
allow you to inspect any system at any time with no interruption
to process, thus allowing a more accurate assessment of
the electrical systems condition to be completed.
REMEMBER infrared windows are not designed to protect you
from an arc flash incident they are designed to allow a
thermographer safe access to inspect the condition of electrical
switchgear, transformers, etc., and thus REDUCE the RISK
of failure through regular, safe, live inspections.
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