Emergency power is essential for every health care facility. It has been a requirement in the National Electrical Code and other codes and standards for many years and is typically a condition of licensure.

While these requirements are well-known to health facilities professionals, they may want to consider going beyond these minimums.

Considering more

Within a hospital, minimum emergency power ensures adequate power for egress and task lighting, alarm and communication systems, medical gas equipment, suction and ventilation systems as well as selected receptacles and heating in most patient care areas.

A typical emergency power code minimum hospital design, which would include a single generator with a 24-hour fuel tank and three standard transfer switches feeding each of the critical branches, can be viewed in Figure 1.

Click figure to open larger version

Because such minimally designed emergency power systems may not provide adequate redundancy or a level of service that allows a hospital to fully function during or immediately following a disaster, there remain a number of areas in a hospital’s emergency power that could go beyond the required minimums. Such a “minimum-plus emergency power” system would include the following:

Additional receptacles in patient care areas. Currently, the minimum requirement for emergency power receptacles within standard patient care areas stands at one duplex receptacle. However, this does not meet the needs of today’s hospitals. Indeed, there could be up to 12 types of electronic devices and equipment needed in the basic patient bed area, including patient bed, computers (for nurse, patient or visitor), monitor, ophthalmoscope, infusion pump, extremity compression device, patient refrigerator, clock, television, portable X-rays and other devices. For a critical care bed, which has a far higher need for electronic devices, the minimum code requirement is only one receptacle greater (i.e., two duplex emergency power receptacles to meet the minimum emergency power requirement).

A minimum-plus emergency power design would include between six and eight duplex emergency power receptacles on two dedicated circuits for each standard patient bed. For a critical care bed, a minimum-plus design would generally recommend a minimum of 12 duplex emergency powered receptacles on three dedicated circuits. This is important because patient needs are not disrupted when equipment is transferred from normal to emergency power receptacles when an outage occurs.

Additional automatic transfer switches. Codes require that patient care areas have both normal and emergency power in the event of a transfer switch failure. Typically, normal power receptacles are rarely utilized or used until there is an outage when the equipment is moved to emergency receptacles. A minimum-plus emergency power design as permitted by code includes multiple critical branch transfer switches so all power is continuous for critical care beds, ED exam rooms and operating rooms.

Additional fuel capacity. The code minimum for emergency power fuel often varies by state. The National Fire Protection Association (NFPA) minimum is 24 hours for a hospital. While this is adequate for the majority of electrical utility outages that last a few hours, the hospital can run out of fuel within 24 hours in a severe disaster. To this point, the Federal Emergency Management Agency (FEMA) estimates a response mobilization time of 72 to 96 hours. For hospitals to ensure they have fuel beyond 24 hours, they might be well-served by increasing fuel capacity to carry the generator load for 96 hours. (The current rewrite of NFPA 99 includes this requirement.)

Built-in redundancy. While NFPA 99 has no specific code requirements for redundancy, it does have a general requirement for emergency power continuity (i.e., the design should take into consideration elements that minimize interruptions due to internal failure). All engineers and facility managers know that as an outage lengthens, the stress on the systems increases—as does the risk of a generator failure. If a hospital lacks a redundant generator, the failure of a generator can shut down some or all of the systems required during a power outage.

On the other hand, a redundant emergency generator allows the systems to remain operational when a generator fails. It also allows the hospital to rigorously test the emergency power system without fear of a generator failure. Having a redundant generator as part of a paralleled generator system allows the hospital another option. It can use the spare and redundant capacity of the emergency power system to serve loads that are not required to be on emergency power, such as cooling. In this way, a hospital can maintain patient care continuity by keeping the hospital environment at a reasonable temperature.

Figure 2 shows a minimum-plus emergency power design for a hospital with N+1 generator redundancy, a 96-hour fuel supply as well as multiple transfer switches for the critical and equipment branches and a transfer switch to supply loads not typically on emergency power, such as cooling.

Click figure to open larger version

Extra chill capacity. Without cooling, the essential procedures and systems within a hospital will overheat and have to be discontinued or shut down within a few hours of an event. On the other hand, adding chillers, associated pumps and cooling towers to the emergency power system or even serving them from a dedicated backup generator would be the first step in keeping a hospital fully operational during a power outage.

Once cooling is supplied with backup power, a hospital can function as if there were no power outage. Adding nonemergency loads to the emergency power system ensures that the hospital will be fully operational, and patient care and clinical outcomes will not differ from regular conditions. (The table below compares minimum emergency power code design with a minimum-plus emergency power design.)

Selling the plan

Knowing what minimum-plus emergency power design involves is only a first step. Health facilities managers have been relaying doomsday scenarios to the C-suite for years when requesting emergency power upgrades. But what if the rationale of impending doom doesn’t seem to convince hospital administrators about the importance of an upgrade? Why not try a systematic emergency power master plan composed of a feasibility study and customized dashboard models?

The feasibility study will evaluate a hospital’s existing emergency power system by answering a number of questions such as the following:

• Does the existing system utilize centralized or distributed generators?
• If the current emergency power system is distributed, is there an opportunity to centralize the system?
• What is the existing and future emergency power load for the campus?
• How will potential locations for new generators impact air intakes, noise levels for patient areas and the surrounding community?
• How will the location facilitate tying in existing loads scheduled for reconnection?

Customizable, off-the-shelf software can be used to help health facilities professionals develop the dashboard models.

Figure 3 shows a customized dynamic dashboard displaying load scenarios based on changes in a number of variables. Ultimately, this Reliable Power Determinator™ reveals future power options. One can instantly see the impact of additional square footage on an existing or proposed power plant. It can be set to determine which air handlers can be included on emergency power without adding an additional generator. It can reveal the size of a future addition if a hospital installs an additional generator or tell how many tons of cooling can be served while on emergency power.

Click figure to open larger version

Similarly, Figure 4 shows a custom dashboard called the Emergency Generator Phasing Planner™, which displays different phasing scenarios to be used when designing a hospital master plan. It relays different “pay-as-you-go” budget scenarios for emergency power outlays in order to meet capital funding priorities.

Click figure to open larger version

When to implement

Hospitals should be able to get through the first hours of an outage with little concern. But what happens if a larger disaster occurs? How is a hospital expected to perform? How does hospital leadership determine its level of preparedness in terms of emergency power?

The following are some basic criteria hospital executives might use to determine their need for minimum-plus emergency power:

Community expectations and hospital mission. Hospitals have developed strong community ties over the decades. This dedication to the health and preservation of community has many hospitals committed to being major refuges during a disaster. Hospital mission statements often also express this commitment.

Type of facility. A tertiary hospital or regional medical center can vary substantially from smaller, rural hospitals in terms of emergency power requirements. In general, the former types are much larger and tend to have broader service lines. As a result, the smaller hospitals may send patients to the larger specialized hospitals in a disaster. Predictably, these larger hospitals might need to consider minimum-plus emergency power to remain fully operational during a power outage, which would include a functioning kitchen and cafeteria, and 100 percent emergency power for critical and emergency care areas as well as for imaging and cardiology.

Location, location, location. Unfortunately, just about every location has the potential for a massive disaster. That’s the case for hospitals in the Southeast within 100 miles of the Atlantic Ocean or the Gulf of Mexico. It’s the same for hospitals in areas prone to crippling ice storms or heavy snows. Then, there are hospitals located in high-risk earthquake areas or even those in the Northeast, with its fragile utility power grid. Facility emergency management committees in every U.S. hospital need to evaluate potential risks and develop an emergency power plan for meeting operational needs.

New construction or a major renovation. It is not feasible for all hospitals to undertake a large engineering project just to become fully operational during a power outage. However, minimum-plus emergency power design concepts can be included during the next new construction or major renovation project. Hence, an awareness of these possibilities is extremely important so they can be exploited when the time is right.

How much is enough?

While it’s doubtful that a utility outage of 24 hours will result in the loss of a patient’s life in this country, it is possible that the effects of a serious catastrophe could be mitigated by a hospital having a minimum-plus emergency power system.

Thus, when considering worst-case hazard scenarios in the strategic planning process, hospital leadership would be wise to consider minimum-plus emergency power.

Doug Stover, P.E., LEED AP, is principal and director of electrical engineering for FreemanWhite, Charlotte, N.C. He can be contacted via e-mail at dstover@freemanwhite.com.

Table: Emergency Power

Minimum versus minimum-plus design

Minimum design	Minimum-plus design	Minimum-plus benefit
Single or multiple generators without redundancy.	Multiple generators serving the emergency load with N+1 redundancy for the required  loads.	Enables required loads to remain in service in the event of a generator failure. Also, rigorous testing of the system is facilitated.
A single automatic transfer switch (ATS) for each of the three required branches of emergency power.	Additional ATSs on the equipment branches of emergency power.	Multiple equipment branch ATSs give the facility the flexibility to prioritize which systems will get power when there is a decrease in emergency power system output.
Normal and emergency power in: Emergency department; Operating rooms; and Critical care imaging.	Add another critical branch to serve the critical areas that are typically fed by the normal power system.	Allows the hospital to be fully operational during an outage because all critical areas can be fed from the emergency power system.
Provide 24 hours of on-site generator fuel.	Increase on-site fuel capacity to 96 hours.	The Federal Emergency Management Agency currently estimates its response time is between 72 and 96 hours following an event. For the vast majority of outages, it would be possible to refuel within a 96-hour time frame.
Cooling on emergency power is not required.	Provide cooling on emergency power.	Without cooling, some service lines will be forced to shut down within hours and patients would be evacuated after a day or two. To remain fully operational, emergency power must include cooling.

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Sidebar - N.C. hospital upgrades power system

In 2004, Forsyth Medical Center in Winston-Salem, N.C., was planning a 350,000-square-foot addition to its existing 1.5 million-square-foot campus. “Like many U.S. hospitals today,” says Van Hauser, CHE, CHFM, director of construction project operations, corporate real estate and construction, Novant Health, Winston-Salem, N.C., “a decentralized emergency power system supplied the Forsyth campus and we assumed this system would continue with the new addition.” Nevertheless, early planning discussions led the facility management team to commission an emergency power study. The results of the study supported a centralized emergency power system placing five 1,500-kilowatt generators in a central plant. However, just as the team believed it had found a design solution that would serve the emergency power needs for the campus for the next 30 years, Hurricane Katrina happened, forcing the hospital to rethink its requirements. In the early post-Katrina days, most of the nation’s hospitals valiantly researched the possibilities of gaining enough emergency power to be fully operational again. “We also hoped that further study during our master planning process would reveal another design solution that would ease our minds relative to emergency power while preserving our budgets,” Hauser recalls. After capturing the variables and data for analysis, facilities professionals needed to make calculated decisions on emergency power needs and budgets. Unfortunately, the project team found their spreadsheets too numerous and cumbersome to review. In the end, the team devised a better way to analyze alternative emergency power scenarios through interactive dashboards and to protect the budget through a staged implementation process. “Our master plan resulted in a centralized generator plant with 8 megawatts,” Hauser says. “Through four additional stages, Forsyth Medical Center will have 100 percent backup emergency power so it can remain fully operational during a lengthy and extensive power outage.”

This article first appeared in the January 2009 issue of HFM.

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