UFC 3 -520-01
June 10, 2002
Installations with small footprints such that a vented battery with adequate power
density will not fit within the available space.
Locations in which the consequences of electrolyte leakage cannot be allowed. For
example, some buildings cannot tolerate the consequences of electrolyte leakage
into the internal wiring spaces between floors. A vented lead-acid cell can leak its
entire electrolyte reserve if the container fails; a VRLA battery will have little or no
leakage upon container failure. UPS systems are often located in areas that
necessitate the use of a VRLA battery.
14-1.1.6 Just as VRLA batteries have applications in which they will be preferentially
used, there are also applications in which their use should be avoided. Do not use
VRLA batteries in the following types of applications:
Unregulated environments that can experience abnormally high and low
Unmonitored locations that seldom receive periodic maintenance checks. VRLA
batteries have shown a tendency to fail within only a few years after installation.
Critical applications, unless the installation location requires the features available
only in a VRLA battery.
14-1.1.7 Apply the following service life for life -cycle cost comparisons of stationary
Small VRLA batteries 3 years.
Large VRLA batteries 7 years.
Small vented lead acid batteries 10 years.
Large vented lead acid batteries 15 years.
Nickel-cadmium batteries 15 years.
Battery Areas and Battery Racks.
14-1.2.1 Locate stationary batteries within a protective enclosure or area accessible
only to qualified personnel. A protective enclosure can be a battery room, control
building, enclosure, or other equipment that will protect the contained battery and limit
the likelihood of inadvertent contact wi th energized parts.
14-1.2.2 Provide space around batteries to allow safe inspection, maintenance,
testing, and cell replacement. When required by the battery size or battery type,
provide space above the cells to allow for operation of lifting equipment, addition of
water, and taking measurements. Provide working clearances in accordance with NEC