7x24 Magazine 2015 Spring

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