The new NEC Standard, Article
110.16 Flash Protection states that, "Switchboards,
Powerboards, Control Panels and Motor Control
Centers shall be field marked to warn of potential
arc flash hazards."
Bureau of Labor Statistics data for 1994 shows
over that 11,000 days away from work resulted
from electrical burns, fires, explosions, and
electrocution/electrical shock. Out of 6,588 work
related fatalities, 548 resulted from electrical
related causes.
An arc flash occurs when a conductive object gets
too close to a current source, or by equipment
failure. Accidents such as dropped tools, a buildup
of conductive dust and dirt, corrosion, and accidental
contact with electrical systems are the most common
causes of arc flash injuries. Prevention involves
setting up flash protection boundaries within
which Personal Protective Equipment must be used.
Another important component is
proper labeling
which warns of arc flash and other electrical
hazards.
|
Arc flash labels are
available as either pre-printed
labels, such as the arc flash labels
shown here, or a label printer can be
used to create both standard and customized
warning labels. |
 |
An arc flash 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:
- Identify equipment and components that
have a potential arc flash hazard.
- 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 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 boundaries 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.
