of Occupational Safety and Health
(NIOSH) defines arc flash as “the
sudden release of electrical energy
through the air when a high voltage
gap exists and there is breakdown
between conductors”. The results can
be absolutely catastrophic with the
production of enormous pressure,
sound, light and heat. For those
unfortunate enough to be anywhere
near an arc flash they can see heat
reach 35,000 degrees—four times
hotter than the sun’s surface. Those
same workers can also be exposed to
molten shrapnel, and burns, vision
and hearing loss can be common
physical results of the aftermath.
From an architectural perspective, the
increase of phased, multi-tier modular
data centers with shared components
such as switchgear, paralleling gear
and distribution boards, has increased
the risk of arc flash due to the adding
of equipment to a live (energized)
backplane. This issue is exacerbated
by the high cost of downtime that
increasingly has generated a desire
on the part of facility’s operators to
make changes or modifications
without “shutting anything down”.
From a legal perspective, regulation
has outlawed “business reasons” as a
valid excuse for live work. Thus, more
work is performed in a live
environment than can safely be
justified, with the line between
troubleshooting and actual
maintenance in a live environment
becoming increasingly blurred.
Both the National Electrical Code,
and the National Fire Prevention
Association (NFPA) in their 70E
standard have defined guidelines to
prevent incidents of arc flash. From
the prospective of a data center
customer, most providers will not
proactively provide information as to
whether actions like common
equipment maintenance are
performed on energized equipment.
Lack of required labeling for arc flash
regulations should alert prospective
buyers to providers who are not
compliant with the latest policies for
health and safety. Ultimately, per
NIOSH, “The organization has a
responsibility in preventing arc flash
injuries… Organizations have the duty
to provide appropriate tools, personal
protective equipment, and regular
maintenance of equipment and
training. A commitment to training is
a commitment to safety”.
Unfortunately, in too many instances,
it is still up to the customer to make
these inquiries to ensure the health
and well-being of site personnel are
factored into their operating
procedures.
ALL THE POWER YOU
NEED…UNTIL YOU NEED IT
Although oversubscribing on power
isn’t subject to any documented
standard, it is a common practice of
many providers that end users must
be aware of. Unless capacity is
added, the power load of a data
center is fixed. For end users in
shared colocation facilities this means
that the site’s power is apportioned
between the end user and the other
firms with data centers within the
facility. Realizing that not every end
user is operating at peak capacity,
many providers use a practice
referred to as “oversubscription”
when contracting with their end users
for power. In the early days of the
wholesale data center space, users
could be certain that oversubscription
was not in place. In those days, only
retail providers oversold power
capacity. More recently, as wholesale
and retail lines have blurred,
customers that are contractually
buying a certain amount of kW
capacity should take extra steps to
ensure that their capacity is NOT
oversold.
In an oversubscribed situation the
provider’s guarantee for the power
contracted for by the end user is
based on the knowledge that, very
often, not every end user is operating
a peak capacity. Thus, the peak use of
one is offset by the less intensive use
by others within the facility.
Unfortunately, in an oversubscribed
mode, power becomes a scarce
commodity as the intensity of use for
one of more tenants increases and
ultimately leads to the provider being
unable to deliver on the level of
power contracted for. Additionally, in
multi megawatt facilities, the core
issue has to do with how this
oversubscription is managed. This is
often a labor intensive effort with
many opportunities for human error.
Prospective colocation customers
should always understand a potential
provider’s power policies before
entering into an agreement.
This pattern of devolution from
industry standards places a greater
burden on today’s data center
customers. Failure to ask for, and
receive, objective evidence of a
provider’s adherence to the standards
that underlie their performance claims
places the customer in the position of
having to make their decision based
more on the sizzle rather than the
steak. Caveat Emptor (let the buyer
beware) was the advice of the ancient
Greek’s to wary prospective
customers, in the world of data center
standards compliance; it’s still good
advice.
7X24 MAGAZINE SPRING 2015
Chris Crosby is the Founder and CEO of Compass Datacenters. He can be reached at
ccrosby@compassdatacenters.com