Efficient Plant November 2017 - 29

feature | electrical-power solutions

ee is complying with safety-related work practices.
The annual audit requirement applies to work
involving electrical equipment.
Beyond worker training, there are additional work
practices that help mitigate arc-flash dangers:
 Maintain a single-line diagram. A data-center
manager must maintain an accurate, up-to-date,
and legible single-line diagram of the operation.
Building-maintenance personnel, electricians, and
engineers rely on a single-line diagram as a map to
guide them around the electrical system, making
this schematic essential for documenting, troubleshooting, and communicating information about
the system.
 Maintain electrical equipment. NFPA 70E
specifies that the equipment owner is responsible
for electrical-equipment maintenance and documentation of that maintenance. To reduce the risk
of failure and the subsequent exposure of employees
to electrical hazards, data-center managers must
conduct maintenance in accordance with manufacturer instructions or industry consensus standards.
Industry consensus standards include American
National Standards Institute/InterNational Electrical Testing Association Standard for Maintenance
Testing Specifications (ANSI/NETA MTS) and
NFPA 70B Recommended Practice for Electrical
Equipment Maintenance.
 Determine protection requirements. A required
arc-flash analysis identifies the presence and location of potential hazards and provides information
to help personnel select proper PPE. Note that
section 110.1 G of NFPA 70E states that elimination,
substitution, engineering controls, awareness, and
administrative controls are all preferred over use of
PPE. However, because of the nature of data centers,
use of PPE is necessary. Additionally, NFPA 70E dictates that the arc-flash boundary distance must be
calculated for all locations where the voltage exceeds
50 V and where there is a possibility of performing
energized work such as maintenance, diagnostics,
and testing.
 Apply hazard labels. NEC and NFPA 70E require data-center owners to apply an arc-flash hazard warning
or label to electrical equipment in the field including

NOVEMBER 2017

switchboards, switchgear,
panel boards, industrial
control panels, meter
socket enclosures, and
motor-control panels
that are likely to require maintenance
while energized.
Arc-flash-hazard
labels must include
information on nominal system voltage,
arc-flash boundary,
minimum arc rating of
clothing, site-specific level of
PPE, and one, but not both, of
the following:
+ available incident energy and
the corresponding working distance (if
the arc-flash boundary was calculated through
engineering analysis)
+ arc-flash PPE category in the NFPA 70E tables
(if the table method was used to calculate arcflash boundary).
 Perform a battery-related risk assessment. Prior
to doing any work on a battery system, a risk assessment must be performed to identify the chemical,
electrical shock, and arc-flash hazards; and assess
the risks associated with the tasks to be performed.
Keep in mind that if a data center is noncompliant
with applicable standards, it jeopardizes the overall
safety of its workers and potentially faces other costly
consequences. EP

An arc-flash
explosion
can throw
a worker's
body across
a room.

Information in this article was provided by Steve
Park, P.E., technical services manager of Electrical Reliability Services at Vertiv (vertivco.com, Columbus, OH),
which was formerly known as Emerson Network Power.
Park received his Bachelor's and Master's degrees in electrical engineering from Purdue Univ., West Lafayette,
IN, and an MBA from Indiana Wesleyan Univ., Marion,
IN. He has been a registered professional engineer
since 1992. For more information on issues of electrical
safety and data-center management, email steve.park@
vertivco.com.
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