Efficient Plant November 2017 - 28

feature | electrical-power solutions

The root
cause
of many
arc-flash
accidents is
insufficient
training.

many people were suffering injuries due to arc-flash
incidents.
Early adopters subsequently took steps to establish
the first set of practices designed to better protect employees and electrical contractors. Soon after, others
recognized the need for additional protection against
arc-flash hazards and new requirements were created.
Today, the Occupational Health and Safety Administration (OSHA, osha.gov, Washington) sets out
the legal requirement for employers to provide a safe
work environment, and its regulations are enforceable
under federal law. NFPA serves as the world's leading
advocate of fire protection and has published more
than 300 consensus codes and standards.
Together, OSHA and NFPA are working to ensure
safe working conditions. Although OSHA outlines
general requirements, in many cases it doesn't explain
how to meet them. This is left to national consensus
standards.
There are essentially four main regulations governing arc flash:
 OSHA Standards 29 CFR, Part 1910: Occupational Safety and Health Standards, subpart S
(electrical) standard number 1910.333 specifically
addresses standards for work practices and references NFPA 70E.
 NFPA Standard 70: National Electrical Code
(NEC) contains requirements for warning labels.
 NFPA 70E: Standard for Electrical Safety in the
Workplace provides guidance on implementing
appropriate work practices that are required to
safeguard workers from injury while working on or
near exposed electrical conductors or circuit parts
that are or become energized.
 IEEE 1584: Guide for Performing Arc Flash Hazard Calculations provides a method of calculating
the incident energy to define the safe working distance and aid in selection of overcurrent protective
devices and personal protective equipment (PPE).

ENSURING SAFETY AND COMPLIANCE
In 2016, three of OSHA's 10 most frequently cited
violations were related to electrical-system practices
and procedures. For data-center owners and operators, the first step in avoiding such citations is to audit
their sites' safety policies and programs. These types

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of audits should take place every three years and be
documented, noting any deficiencies that need to be
addressed.
NFPA 70E requires employers to develop, implement, and document an overall safety program. The
program must be designed to train employees and
instill an awareness of electrical hazards. It should
identify hazard/risk evaluation procedures, required
tools and PPE, electrically safe work procedures, and
risk-mitigation strategies.
Mitigation of arc flash and related hazards has a lot
to do with training. The root cause of many arc-flash
accidents is insufficient training. That situation, in
turn, results in failure to follow appropriate procedures or take necessary safety precautions on the job.
The following strategies can help facilities comply
with NFPA 70E (which is the best way to ensure compliance with OSHA codes and regulations):
 Qualify workers: OSHA and NFPA recognize the
importance of ensuring worker qualification. To be
qualified to work on or around electrical equipment, a worker must demonstrate the ability-not
simply familiarity-to use special precautionary
techniques and PPE. This includes arc-flash suits,
insulating and shielding materials, and insulated
tools and test equipment. Qualified persons who
perform maintenance on electrical equipment and
installations must also be trained and familiar
with the specific maintenance and test procedures
required.
 Train all at-risk workers: Employees who work
around (not just on) energized electrical equipment
must be safety trained, preferably through an instructor-led course, as opposed to web-based training.
Qualified electrical workers permitted to work within
the limited approach boundary of exposed energized
electrical conductors and circuit parts operating at 50
V or more must be trained to understand and observe
minimum approach distances to exposed parts.
Retraining must occur at least every three years,
whenever new procedures or practices are introduced,
or when an audit indicates a need for additional training. All employee training must be documented and
training programs audited every three years.
 Evaluate workers annually: Data centers must
conduct annual inspections to ensure each employ-

NOVEMBER 2017

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Table of Contents for the Digital Edition of Efficient Plant November 2017