DAS and SmallCell Solutions0 pages

About NEC Class 2

Alpha Technologies Powers NYC Subway DAS

With over 277 underground stations and an
annual ridership exceeding more than one
billion, the New York City subway system is
the largest and most established of its kind
in North America. In 2011, an ambitious plan
was developed by Transit Wireless and the
Metropolitan Transportation Authority (MTA)
to use DAS as a means of blanketing all 277
underground subway stations with mobile
voice and data coverage for commuters,
emergency and security services. Given
the critical nature of this application and the
harsh, variable subterranean environment,
Alpha was brought in to design a customized
power solution that could withstand extremes

of temperature, moisture, vibration and
shock, while meeting all the operational load
requirements such as battery backup time
in the event of a grid failure. Alpha’s solution
came packaged as a ceiling mounted cabinet (able to support 250lbs of gear, with an
Ingress Protection rating of 66), FXM 2000
outdoor rated UPS module and AlphaCell
85GXL batteries. Expected to be completed
by 2016, the network will host services provided by the four biggest wireless carriers,
AT&T, Sprint, T-Mobile & Verizon and others.
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See our other case studies at
www.alpha.ca/case-studies

Major wireless carriers and DAS integrators in the US and Canada are using Alpha’s
power systems to backup their IDAS and ODAS nodes, e.g.
IDAS - PNC Park, Pittsburgh

IDAS - Century Link Field, Seattle

IDAS & ODAS - PPL Park, Philadelphia

IDAS - Husky Stadium, Seattle

ODAS - NYC Subway, New York City

IDAS - Safeco Field, Seattle

ODAS - Chicago Transit Authority, Chicago

IDAS - JW Marriott, Palm Springs

IDAS - Houston Subway, Houston

IDAS - Coliseum, Los Angeles

IDAS - Sports Authority Field at Mile High, Denver

IDAS - MGM Grand, Las Vegas

IDAS - Bankers Life Field House, Indianapolis

IDAS - Venetian, Las Vegas

IDAS – Texas A&M University, College Station

ODAS - University of Cal Football Stadium

ODAS - Oakland Bay Bridge, San Francisco

ODAS - City of Palo Alto

The National Electrical Code defines
a Class 2 circuit as that portion of the
wiring system between the load side
of a Class 2 power source and the
connected equipment, such as the
IDAS remote device. The Class 2 power
source is limited to 100 Watts of output
power per circuit and cannot exceed
60Vdc. Due to its power limitations, a
Class 2 circuit is considered safe from
a fire initiation standpoint and provides
acceptable protection from electrical
shock. Because it is deemed low risk,
a Class 2 circuit can be installed by
DAS technicians over conventional
surface-mounted cable.
In order to meet the 100W restriction,
the power equipment must employ
some form of active current limiting
circuitry. Without the 100W guarantee,
remotely powering the distant devices
requires that the cable be armored or
enclosed in conduit, and that the site
be certified by a licensed electrician.
Since the latter approach is so costly,
most DAS providers have looked to
use line power equipment like Alpha’s
eLimiter+ to meet the NEC requirements.
Though products like eLimiter+ have
significantly reduced the cost of IDAS
installations, there persists a common
misconception that low cost, conventional
fuse panels can meet Class 2 provided
they are fused appropriately. This belief is
incorrect because the power distribution
device must meet the 100W requirement
even when the primary protection device
(i.e., the fuse) is bypassed. The end result
is that conventional fuse panels are not
compliant with NEC Class 2, though they
may be used if the provider elects to incur
the expense of conduit and a licensed
electrician.

Contact our Power Experts and find out why:

1.800.667.8743

sales@alpha.ca

www.alpha.ca

The Alpha Group Alpha Technologies Ltd is a proud member of The Alpha Group - an alliance of independent companies who share a common philosophy – to create world class powering solutions.
Collectively, Alpha Group members develop and manufacture AC, DC and renewable power conversion, protection and standby products, featured in millions of operational installations around the world today.
Copyright © 2015 Alpha Technologies. All Rights Reserved. Alpha® is a registered trademark of Alpha Technologies.
member of The Alpha Group™ is a trademark of Alpha Technologies.Cordex™ is a trademark of Alpha Technologies Ltd.

0470212-00 Rev A (05/2015)

Alpha Powers

DAS & Small Cells