60
7X24 MAGAZINE FALL 2014
arTiCle 480: sTorage
BaTTeries
Article 480 has been expanded
adding to the code many
industry best practices for
installation which now makes
them mandatory and enforceable
by the local Authority Having
Jurisdiction (AHJ).
Uninterruptible Power Supply
(UPS) systems often use
stationary storage battery
systems to maintain power to
critical IT equipment when other
power sources are unavailable.
There are different battery
technologies on the market; the
most commonly used in data
centers are vented type (flooded
wet cell) or sealed type (valve-
regulated). Many batteries emit
hydrogen gas during normal
charging cycles, vented batteries
more than sealed batteries. To
coordinate with building and fire
safety codes
NEC article 480.9
requires provisions “appropriate
to the battery technology” be
employed to prevent the
accumulation of explosive or
otherwise harmful gasses.
Therefore, the electrical AHJ will
now also enforce this
requirement.
Battery installations must comply
with article 480.9(C), which
references 110.27 for
guarding
of live parts
. Minimum front and
top clearances are indicated.
Additional clearances should be
considered to enable access for
rigging equipment used during
future battery replacements.
Battery rooms may also contain
emergency showers, eye washes
and spill containment, all of
which should not encroach on
the dedicated equipment and
working spaces.
arTiCle 645:
informaTion
TeChnology
equiPmenT (iTe)
Article 645 covers equipment
and installations for ITE rooms.
ITE rooms are power intensive
and cooling sensitive
environments; two aspects which
present many unique safety
challenges. Article 645 permits
the use of alternate, less
stringent wiring methods,
provided that all six conditions
listed in 645.4 are met.
Requirements and descriptions
for HVAC systems in ITE rooms
are clarified under 645.4 Special
Requirements.
Non-plenum rated power cables,
communications cables, cord-
and-plug connections, and
receptacles are permitted to be
installed below a raised access
floor used as an air plenum,
provided the provisions of
645.5(E) are followed. Previous
editions required smoke
detection under the raised floor
to cease the circulation of air
upon the detection of smoke.
The requirement for
under floor
smoke detection and to stop air
circulation under the floor was
removed
from 645.5(E)(4).
Smoke detection under the
raised floor may be required by
other building codes or
standards but is no longer
required by the NEC.
Article 645.14 System Grounding
was added to specifically indicate
that separately derived
grounding systems shall meet
the requirements of Article 250.
In addition 645.15 states that
grounding and bonding shall
comply with article 250.
Declaring an ITE room as a
Critical Operations Data System
in order to
not install EPO
switches
triggers a requirement
to
selectively coordinate
overcurrent protective devices in
accordance with 645.27. This
requirement makes the design
and installation more
complicated and expensive.
Example of a Vented Lead-Acid Battery
Installation
