Potential Disaster During An Electrical Power Outage


During the major Northeast blackout in 2003, numerous emergency generators in the New York City area failed within the first 30 minutes, mostly due to lack of regular maintenance, failure to test generators under a full load, and fuel supplies contaminated by old, jelled fuel that had sat in day tanks and other storage tanks too long. This issue is one that clearly is not addressed in most buildings possessing generators and seems too commonplace.

The following case study was prepared by Jack J. Smits, M.Eng., P.Eng., of Manulife Real Estate in Canada:

The scenario — The focus of this case study is a 40-plus-story, 1970s-era commercial high-rise building in downtown Toronto, Ontario. The building possessed several emergency generators. In case of electrical power failure, separate emergency power is dedicated to the ground-floor retail and banking facilities. The fire pumps were diesel driven. The gearless elevators in the low-rise, mid-rise and high-rise banks had been upgraded to computerized variable-speed AC drives, solid-state rectifiers hoist motors. The previous DC generators that drive the DC hoist motors had been replaced.

In a power outage, the relatively large No. 1 emergency generator in the penthouse would power the mandatory building life safety systems, such as stairwell and floor emergency lighting, exit lighting, fire panels and annunciators, PA system, smoke exhaust fans, stair pressurization fans, one elevator per bank for firefighter use, air compressor controls, basement sump pumps and the building's boiler. Several automatic transfer switches would automatically and sequentially switch the various life safety systems over to the emergency power generator in the event of an electrical power failure.

Some major tenants with continuous business operations (CBO), where business is conducted 24/7, were provided with 208-volt/three-phase/60-amp emergency power from a second generator for emergency operation of essential equipment such as selective lighting, power for computers and servers in air conditioned hub rooms that powered all tenant computerized telecommunications and Internet servers. Most, but not all, high-tech tenants with servers had installed an uninterruptible power supply (UPS) unit with battery backup to allow for continuous electrical power supply to avoid momentary power loss that would otherwise require rebooting of the computers and servers.

Emergency testing — The computerized and direct digital control of all building heating, ventilating and air conditioning (HVAC) and lighting systems was by a building automation system that upon power failure would lock out all equipment and allow an organized re-start to prevent overloading and surges when normal electric power was restored.

Reportedly, both building emergency generators were tested monthly under part-load conditions and yearly, in accordance with National Fire Protection Association (NFPA) testing criteria while using a load bank for minimum 75% generator capacity. Because some tenants with CBO requirements were connected to the spare capacity of the building emergency generator and some smaller tenants were without UPS protection, the monthly testing of the No. 1 emergency generator in the penthouse was limited to selective testing of automatic transfer switches for stairwell lighting and elevator operation only.

Power failure — When the eastern grid power outage occurred on Aug. 14, 2003, at 4:15 P.M., it was the largest in North American history. It was restored the next morning with limited capacity. Several U.S. states and all of Ontario were impacted. The generators in the building as described above started promptly and the automatic transfer switch switched to emergency power. However, the delay timing of the automatic transfer switch loaded the No. 1 generator up rather quickly, which resulted in a significant voltage drop due to nearly locked rotor conditions. It locked out all solid-state rectifier-driven elevators that only tolerated a 5% voltage drop. That would now require manual reset with elevator technician involvement. The elevators failed to descend to the ground level and left passengers trapped in stalled cabs on upper floors. The stairwells were still lit and building occupants were now exiting the building. With the elevators shut down, the operating staff was unable to enter the exit stairs and reach the penthouse No. 1 generator due to heavy evacuee stairwell traffic.

In addition, one of the automatic transfer switches failed initially or subsequently for particular equipment that had not been exercised during previous testing and which included the control air compressors. The generators still running full bore required cooling of the radiators and pneumatically operated NC (normally closed) outside air dampers provided cooling of this room. With the control compressor shut down and with diminishing control air pressure, the dampers started to close. As a result, the emergency generator room began to overheat and one of the sprinkler heads activated, releasing water onto the generator and starter equipment. The emergency generator then shut down.

At this point, the office floor emergency lighting and stairwell lighting also shut down. Building occupants who had remained behind while waiting for power to be restored were now forced to exit the building and were confronted with pitch-black stairwells that had no fluorescent tape to indicate stair level, landings or treads. People in stairwells who went by feel of railings tripped and stumbled, causing pandemonium. Eventually, the building was vacated and the No. 1 emergency generator restarted and dampers were reset.

Lessons learned — Reportedly, the following building improvements were subsequently implemented:

  1. Full load testing of generators and all automatic transfer switches together, weekly
  2. Automatic transfer switches coordinated for sequential timing and minimum voltage drop of the No. 1 emergency generator
  3. UPS installation by tenants that require CBO
  4. Emergency generator room outside air dampers changed to NO (normally open) position
  5. Emergency generator room electric operation of all outside air and return air dampers
  6. Pneumatic control compressors and storage tanks interconnected with back-up from emergency generator No. 2
  7. Additional stairwell lighting with battery pack lamps (dual lighting system)
  8. Stairwell identification with fluorescent tape to demarcate landings, stairs and floor level
  9. Additional fuel storage
  10. Domestic water pumps on emergency power (CBO requirement for tenant use and to prevent water hammer upon startup)

As noted in the case study, it is very difficult to take a building's power off-line to fully check its emergency backup power source. With many tenants demanding 24/7 operations, but who do not have the luxury of a battery UPS system, it is nearly impossible sometimes for property management to gain permission to conduct these necessary tests. So, they simply tend not to get done. The only way then to determine whether the unit will function under a crisis situation is to have a crisis. Having aged fuel on site, however, is clearly the fault of the management.

During the major firefighting operation by the Philadelphia, PA, Fire Department in the 1991 Meridian Plaza fire, water runoff from the fire attack began to fill the basement after cascading down shaftways, affecting the transformer and switchgear rooms. The building was soon plunged into total darkness. The generator failed shortly after starting and all power was lost to the building for the remainder of the fire.

It was determined later that the wiring chase that the generator would have fed had burned through in the core area where fire was the heaviest, so in reality it did not matter whether the generator functioned or not. Mostly all base building systems tied into the unit would not have had power. It was important to note, though, that the generator did fail when called upon "in the clutch," which is why it is so important to maintain these critical pieces of machinery.

Picture the story in Toronto with a twist — the generator failing just as a transformer vault in the building explodes and catches fire due to an electrical surge from the grid, sending plumes of smoke throughout the tower's core with the darkened stairs filled with evacuees (and no reflective striping or battery light packs in place, as was the case with the Toronto building). Imagine the chaos facing first-due fire crews.

Try to ensure that the high-rises in your response area properly and regularly maintain their emergency generators. It is one more valuable tool that firefighters may need to call upon in a major event and should be considered just as important a tool as the ones carried on the rigs. Without any building power in a crisis, firefighters are clearly playing with a deck that's stacked against them. Imagine climbing 30 flights of steps, fighting your way through a panicked, densely packed crowd in a darkened stairwell where the only substantial light may just be your hand lights. And that's before having to initiate the fire attack with no operational building fans for smoke removal or stair pressurization.

CURTIS S.D. MASSEY is president of Massey Enterprises Inc., the world's leading disaster-planning firm. Massey Disaster/Pre-Fire Plans protect the vast majority of the tallest and highest-profile buildings in North America. He also teaches an advanced course on High-Rise Fire Department Emergency Operations to major city fire departments throughout the U.S. and Canada. Massey also regularly writes articles regarding "new-age" technology that impacts firefighter safety.