Arc Flash Hazards
 An arc flash can happen in as little as 1/1000 of a second. It can result in temperatures
up to 35,000 degrees F. This is four times hotter than
the surface of the sun and can result in fatal burns
up to five feet from the arc, and severe burns at distances
up to ten feet away. In addition, an arc-blast may occur.
An arc-blast results from the rapid heating of air and
the vaporization of metal. This creates a pressure wave
than can damage hearing and cause a concussion resulting
in memory loss. An arc-blast can also result in flying
metal, some of which may be molten.
Prevention
of arc flash hazards involves several steps:
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<> Identify
equipment and components that have a potential arc flash
hazard. The NEC code identifies the following equipment as requiring arc flash labels.
-
Switchboards
-
Panelboards
-
Industrial control panels
-
Meter socket enclosures
-
Motor control centers
<> Use
Lock Out / Tag Out
procedures to ensure equipment is de-energized, or
live components are isolated.
<> Ensure
all potential arc flash hazards are properly labeled.
Standard arc flash labels, such as those shown on this
page can be used. Or use a label
printer to create custom labels that include specific
information such as safe distances and required Personal
Protective Equipment.
Labels which clearly
identify equipment and components are important for
eliminating confusion. In some instances it may also
be appropriate to provide labels with maintenance or
cleaning procedures.
To
ensure you have a safe workplace, and that you are meeting
NEC, OSHA, IEEE and NFPA* requirements, use specialized
arc flash software to calculate protection boundaries.
These include the Flash Protection Boundary, Limited
Approach Boundary, Restricted Approach Boundary and
the Prohibited Approach Boundary.
 <> Provide
employee training. Be sure all employees are trained
so they are aware of the dangers resulting from arc
flashes; they understand the warning labels and signs;
and they know how to use the appropriate PPE. Everyone
working on electrical equipment should be fully trained
and qualified for the job.
NEC
Standard, Article 110.16
Introduction to Arc Flash Safety
Arc Flash Labels
NFPA 70E Electrical Safety Standards
Magazine
Article - NFPA 70E PPE
Current Limiting Fuses
NFPA 70E Arc Flash Blog
* The NFPA 70E requirement
sets the boundary of the area within which flash protection
is required.
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