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Published on May 1, 2019.


Natural disasters and emergency power systems

To the editor:

After reading your recent coverage of last year’s Camp Fire in NFPA Journal [“Old & In Harm’s Way” and “135 Minutes,” January/February], our thoughts went back to the Irma and Maria hurricane disasters in Puerto Rico.

As consulting engineers in Puerto Rico, we have tried to stay ahead of the disasters that have caused so much pain for our country. Long before Irma and Maria, we decided that hospitals required total emergency power backup, and in 1981 we designed our first emergency power system for the Manati Regional Hospital. We have designed total energy emergency systems for four existing hospitals and two new hospitals in Puerto Rico, and all of them faired very well in the aftermath of the hurricanes. The impact on hospitals of Hurricane Hugo in 1989 and Hurricane Katrina in 2005 underscored our decisions regarding emergency power backup.

One of those facilities, the Adult’s University Hospital at the San Juan Regional Medical Center, the island’s main health facility, has an emergency power system designed for two 2,500KW Caterpillar engine generator sets with 20,000 gallons of diesel fuel. The generators powered the hospital at 4.16KV voltage. It was the only hospital self-operating without assistance following the hurricanes at the San Juan Medical Center.

In NFPA 70®, National Electrical Code®, Article 517 on health care facilities is obsolete in its requirements for emergency power in hospitals and must be revised. Weather conditions for both tropical and temperate regions are predicted to alter drastically due to climate change, a condition that will require hospitals to be energy sustainable. In natural disasters, hospitals must not depend upon power companies to deliver power due to the extent of damage to the power grid, as occurred in the California fires and in the Puerto Rico hurricanes.

The power to hospitals must be maintained, not only to sustain the hospital’s usual functions but to maintain equipment such as sprinkler systems, water pumps, waste plants, and others that are vital for the hospital’s operation. Power should also be maintained for some non-essential loads, such as receptacles in patient rooms and lights throughout the hospital.

All hospitals must be designed for 100 percent capacity of emergency generators, and they must have a minimum fuel capacity to run the hospital for at least 48 hours. Hospitals no longer need the three transfer switches for equipment branch, life safety, and critical—they need power for the total capacity requirements of the institution. This must be a mandatory requirement of the National Electric Code®.


Ingenieros Consultores, CSP

San Juan, Puerto Rico

Jonathan Hart, technical lead, fire protection engineering at NFPA, responds:

Many of the essential electrical system performance requirements found in Article 517 have been extracted from NFPA 99, Health Care Facilities Code. The provisions for providing emergency power are intended to be the minimum requirements to provide an adequate level of safety. The approach you have taken in the design of your facility seems to have gone above and beyond the minimum specified in NFPA 99 and Article 517.

NFPA 99 requires that circuits serving equipment that is critical to the immediate survival of patients, provides life safety functions, or is essential to functional facility operation be provided with emergency power for an amount of time determined by the facility in consideration with their emergency operations plan. This allows for a facility or jurisdiction to determine its specific need based on its specific conditions.

In developing the minimum criteria, the technical committees must balance the fact that the code will be applied to various types of facilities in locations around the world. The minimum requirements must be considered along with the requirements for a robust hazard vulnerability analysis that can vary significantly from location to location. What may be needed in one location for one set of conditions may not be the appropriate solution for another location with different considerations.

‘In Compliance’ sprinkler kudos

To the editor:

The “In Compliance” section of NFPA Journal always provides insights that we as members normally can’t get anywhere else. I appreciated the recent article by Brian O’Connor [“NFPA 13,” March/April] on the need for a cabinet with spare sprinklers and a sprinkler wrench for properties with sprinkler systems.

Although the article addresses facility managers directly, it contains information that suppliers of safety equipment, installer/maintainers, and the authority having jurisdiction can also use for compliance and enforcement. The importance of the article is that it not only talks about the NFPA 13 requirements for when to replace sprinklers and what the sprinkler cabinet should include, but also the reasons and insights that only NFPA staff or a committee member would normally know. A sprinkler that has operated or a sprinkler that is impaired for any reason is an unsafe condition that puts people and property at risk. Having a cabinet with spare sprinklers and a tool nearby to quickly place the system in operable condition makes every property with a sprinkler system safe and code compliant.

Thanks to Brian for sharing that knowledge. I plan to share the article with my colleagues and customers.


Brooks Equipment Company

Charlotte, North Carolina

Fire prevention in cold storage facilities?

To the editor:

The current issue of NFPA Journal includes a feature story on the protection of cold storage [“Cold Fact,” March/April]. The article was written by a product manager for Viking and, apart from the last paragraph, concentrates solely on sprinkler systems as the protection methodology.

Sprinkler systems are the best protection methodology for the facility itself—the expectation is that fire will destroy part of the structure’s sandwich panels, but the facility can be repaired and returned to service. The issue here is that the real value isn’t in the facility, but in the stored products. The ratio of the value of the stored products to the value of the facility is currently approximately 7:1, and as facilities become taller, this ratio will increase. For the vast majority of products stored in cold storage facilities, the impact of smoke invariably leaves them unfit for human consumption. As a result, the products are dumped, at a cost far greater than that of repairing the facility.

The risk analysis therefore depends upon whether the storage facility is contracted or whether the owner of the cold storage also owns the stored products. If the facility is contract storage, then it has little if any responsibility for the insurance of the stored goods, meaning a reliance solely on sprinkler protection is probably justified. If there is a common owner of the facility and the stored goods, then sprinkler protection alone is inadequate, as 90 percent of the insured facility and goods will be lost in any fire, with or without sprinkler protection.

Currently, the sole means of fire prevention for a cold storage facility, including the contents, is the installation of a hypoxic, or oxygen-reduction, system. This is a verifiable methodology that has been in use for many years in the European Union, the Middle East, and elsewhere. In the United States, by contrast, these systems are not well understood and there is little application experience. The Fire Protection Research Foundation recently produced a report on the topic, titled “Review of Oxygen Reduction Systems for Warehouse Storage Applications.” In my opinion, the report displayed an absence of practical expertise, and I requested that the Foundation remove this document from its website, or at least include a disclaimer as to the incomplete nature of the document. The Foundation has opted not to do so, which effectively means that the US market is left with minimal ability to use this methodology.

New Zealand has had a performance-based building code for 28 years that offers a platform for the application of alternative fire safety strategies, and hypoxic systems have performed well in warehouse storage applications. I hope the US market will consider that track record as it pursues new methods for warehouse protection.


Clements Consultants

Northland, New Zealand

Amanda Kimball, research director for the Fire Protection Research Foundation, responds:

As Mr. Clements notes, the focus of the recent NFPA Journal article concentrates on fire protection measures for cold storage facilities rather than on fire prevention.

The lack of use of hypoxic prevention methodologies in the United States is due largely to the fact that currently there is no US installation standard for these systems, although there are European standards and an ISO standard under development. Additionally, US codes offer a performance-based design option that would at least allow for consideration of hypoxic systems.

A final important point to consider with hypoxic systems is that the Occupational Safety and Health Administration requires that oxygen-deficient atmospheres within working environments are maintained at 19.5 percent oxygen.

Top Photograph: REUTERS