Smart Equation for Emergency Power at Data Centers: Code + Common Sense
December 23rd, 2013 By: Industry Perspectives
Bhavesh Patel is director of marketing and customer support, ASCO Power Technologies, Florham Park, NJ, a business of Emerson Network Power.BHAVESH PATEL
The devastating impact of hurricanes, tornadoes and other severe weather over the past several years has placed an unprecedented burden on commercial facilities, including data centers that need uninterrupted power to maintain business operation.
As has been evident in the detritus of extreme weather in the U.S. and elsewhere, including this past November’s typhoon in the Philippines and last year’s Hurricane Sandy, codes and standards cannot cover every eventuality. For example, during Hurricane Sandy some generators and fuel sources set up to run emergency backup power in critical facilities – and located within a facility or on a campus in accordance with prevailing code – were unable to operate due to flooding or water damage even though the installation was to code.
For data centers, which rely on a steady and reliable stream of electricity, power interruption can be extremely costly and, in some cases, damaging to a facility’s reputation.
Indeed, the price of lost business productivity stemming from interrupted power can soar quickly. According to a Ponemon Institute study completed in 2011, the average cost of data center downtime based on cost estimates provided by survey respondents was about $5,600 per minute. The average length of reported incident was 90 minutes, which tallies to an average cost per incident of over half a million dollars.
When building new data centers, owners and decision makers involved in the design, construction and operation of the facilities should look beyond code to decide where to place electrical components to ensure reliability of emergency backup power in the face of an extreme weather event.
Go Beyond The Code
For example, NFPA 110: Standard for Emergency and Standby Power Systems, 2013 edition, Annex A, Explanatory Material paragraph A.7.2.4, does say: “EPSS [emergency power supply system] equipment should be located above known previous flooding elevations where possible.” And goes on to state, in paragraph A.7.2.5, “For natural conditions, EPSS design should consider the ‘100-year storm’ flooding level or the flooding level predicted by the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) models for a Class 4 hurricane.”
But these are suggestions, not requirements.
And the NFPA 110 is not particularly specific with respect to flooding. Chapter 7: Installation and Environmental Considerations, paragraph 7.2.4 says, “The rooms, enclosures, or separate buildings housing Level 1 or Level 2 EPSS equipment shall be designed and located to minimize damage from flooding, including that caused by the following:
1. Flooding resulting from fire fighting
2. Sewer water backup
3. Other disasters or occurrences
These references appear in section 7.2.2: Outdoor EPS [emergency power supply] Installations, but are not referred to in the previous section, 7.2.1: Indoor EPS Installations. So unless someone is looking in 7.2.2, they might not even see the references.
And here’s another example. NFPA 70: National Electrical Code (NEC), 2011 edition Article 517 explicitly defines division of a facility’s electrical systems: which loads are essential and which are not. With respect to the essential electrical system, the code defines the equipment system, critical branch, and life safety branch. However, as with NFPA 110 and NFPA 99, the NEC does not address flooding with specificity.
NEC Article 517.35 (C) says, “Careful consideration shall be given to the location of the spaces housing the components of the essential electrical system to minimize interruptions caused by natural forces common to the area (e.g., storms, floods, earthquakes, or hazards created by adjoining structures or activities).” But, again, there are no specific mandates.
Another Issue: Separation of Wiring
Another issue not standardized by code is the separation of wiring to enable adequate emergency coverage. NEC Article 517.30 (C) (1): Separation from Other Circuits states: “The life safety branch and critical branch of the emergency system shall be kept entirely independent of all other wiring and equipment and shall not enter the same raceways, boxes, or cabinets with each other or other wiring.” Though that section of code dictates not placing life safety branch and critical branch wiring in the same raceway to prevent simultaneous, it does not give an actual distance or even detailed guidelines. That is another area where good judgment based on specifics of the installation comes into play.
Code does not specifically warn against placing electrical equipment for emergency power in the basement of a building. For instance, there is no language that precludes having the generator, switchgear, and the paralleling gear located in the basement, where flooding could occur during times of rising water and where components are more likely to be damaged by water. If there is a major problem in the basement, then paralleling switchgear would both potentially be compromised.
NFPA 110, Annex A, paragraph A.7.2.4 says, “EPSS equipment should be located above known previous flooding elevations where possible.” Good advice even if not mandated. But following along that train of thought, in flood zones, breaker boxes, building connections and other critical electrical equipment should be not only “not in the basement” but actually above the ground floor, as well.
Placement of components for emergency power systems in data centers should take into consideration both code and common sense conclusions. What’s good in one location for generator placement and fuel storage – i.e. at a facility nowhere near a river or a shoreline – is not necessarily good for another. Taking stock with code and common sense in mind will make for the best decisions.
Until code catches up with weather realities, it is up to every stakeholder to make sure emergency power components get the best chance possible when called upon to perform as intended.
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