Today, casinos are being built nationwide—this construction is not limited to locales in Nevada and New Jersey. However, we still follow fire and building code requirements that were radically changed by deadly fires in Las Vegas casinos close to 30 years ago.
The most notable casino fire was, of course, the deadly MGM Grand Hotel and Casino fire on Nov. 21, 1980. Fire historians consider this the second-worst hotel fire after the 1946 Winecoff Hotel fire in Atlanta that killed 119 people. The fire at the MGM reportedly killed 85 people, mostly due to smoke and carbon-monoxide inhalation.
A review of the issues discovered during the investigation of the MGM Grand fire points to why we must remain vigilant in the installation methods we use for fire alarm systems. We also must continue to insist on complete testing and maintenance of each fire alarm system, along with all of the interfaced fire safety functions and systems.
Investigators attributed the cause of the MGM Grand fire to an electrical ground fault inside a wall soffit. The wiring powered a refrigeration unit in the deli. Vibration from the unit caused the friction-damaged wiring to fail. This failure initiated an arcing condition that, in turn, caused the fire, which spread rapidly to the casino floor.
The failure of the smoke dampers to operate and control the smoke and toxic fumes distribution throughout the building represented a second breakdown in this fire safety system, which led to multiple deaths.
Most of the deaths occurred in the stairwells. Many people who attempted to use the stairwells as their exit path from the building were trapped when the doors locked behind them. When smoke entered the stairwells below the escaping building occupants, they became trapped and died.
In the early 1980s, casinos and restaurants in Las Vegas (and other jurisdictions) were not protected by automatic sprinklers. An exemption precluded sprinkler protection when a facility was occupied 24 hours a day. The building inspectors who granted this exemption reasoned that occupants would quickly notice any fire, and they reasoned the prompt use of portable fire extinguishers would then contain it. In the case of the MGM Grand, the area where the fire occurred did not operate on a 24-hour basis, and there were no people around when the fire broke out.
Reportedly, the fire alarm system consisted only of manual fire alarm boxes and speaker-type notification appliances located on each floor, with the exception of the first through the fourth levels of the building, where there were no manual fire alarm boxes or notification appliances. When someone actuated a manual fire alarm box, the signal sounded in the security office. For a minimum of five minutes after the signal, the system delayed sounding the fire alarm notification appliances and delayed transmitting the alarm signal to a central station and the fire department. This delay would allow security officers to investigate and confirm the alarm was for a real fire. When the central station finally received the alarm signal, the operators would notify the fire department through the use of a hotline telephone connection.
Obviously, delayed notification of a fire to the occupants or to the fire department can result in a large loss of life. Most owners do not wish to disturb the occupants of their buildings unless they have a real need to do so. Unfortunately, this often results in a very dangerous practice when it comes to the life safety of those same occupants.
As a result of this and other casino fires, such as the Las Vegas Hilton fire a few months later, the building codes, the Life Safety Code and the National Fire Alarm and Signaling Code now contain numerous requirements to help prevent the issues that led to the loss of so many lives. The code gives particular attention to various schemes that may delay the actuation of notification appliances or the transmission of signals to a supervising station or to the fire department.
With respect to delayed notification, for some occupancies, the Life Safety Code continues to allow fire alarm systems to use presignal, positive alarm sequence and alarm verification. However, designers and installing contractors often misunderstand, misuse and misapply these notification strategies.
Alarm verification denotes a feature developed to reduce nuisance false alarms from smoke detectors. This feature confirms that a real fire has actuated a smoke detector by delaying the fire alarm system’s response for up to one minute while the system control unit resets the actuated detector and waits for a second actuation from that smoke detector. Since the 2007 edition of NFPA 72, the National Fire Alarm Code, an installer can only use this feature once a proven smoke detector false alarm issue has occurred.
A presignal system will typically have the initial fire alarm signals sound only in department offices, control rooms, fire brigade stations or other constantly attended central locations. But, transmission of the fire alarm signal to a supervising station or to the fire department must occur without delay. Other general notification appliances throughout the facility will not actuate until an authorized person manually actuates them.
A fire alarm system programmed with a positive alarm sequence (PAS) requires an operator to acknowledge all PAS fire alarm signals within 15 seconds. If the operator does so, it begins a three-minute delay in actuation of the notification appliances and the transmission of signals to a supervising station or the fire department. Notification appliances will actuate in accordance with the building evacuation or relocation plan, and the signal will transmit to a supervising station or the fire department, when any one of the following conditions occur: the operator does not initially acknowledge receipt of the signal within 15 seconds; an operator does not reset the system within the three-minute delay; a second initiating device selected for positive alarm sequence actuates; or any other fire alarm system initiating device actuates.
In all cases in the code, the words “immediately activated” mean the fire alarm system imposes no delays other than the processing of the signal by the fire alarm control unit. As you can readily see from this description of positive alarm sequence, the requirements of the code have removed the unreliable human intervention as much as possible.
The Life Safety Code only permits a casino or other assembly-type occupancy to use positive alarm sequence system where an owner wishes to delay the actuation of the fire alarm notification appliances or delay the transmission of a fire alarm signal to a supervising station or to the fire department.
So, one of the major issues that occurred in the MGM Grand fire led to the change in both the building code and the Life Safety Code to only allow positive alarm sequence signaling in a casino.
The codes also now forbid exit doors from locking behind occupants who exit a building. As discussed previously, many died in the MGM Grand due to the occupants entering the exit stairwells and getting trapped by the doors that locked behind them. The casino required this locking arrangement for the security of the occupants. However, no one apparently thought through the possibility of occupants becoming trapped in a stairwell.
The codes now require that in the event of a fire alarm actuation, all locked egress doors in assembly occupancies must automatically unlock during that alarm condition.
Casinos represent many challenges to the fire alarm system designer and installing contractor, but as you can see from the above requirements, the codes have changed to ensure occupant safety in these unique operations.
When confronted with installing a fire alarm system in a casino, the professional contractor absolutely must reference and understand the applicable codes.
MOORE, a licensed fire protection engineer, frequent speaker and an expert in the life safety field, is a past chair of the NFPA 72 Technical Correlating Committee. Moore is a principal with Hughes Associates, Inc. at the Warwick, R.I., office. He can be reached at firstname.lastname@example.org.