Above the Noise

Bells jingling, people talking, glasses clinking, ratchets rattling as people pull levers, the whirl of the roulette wheel and the shouts of encouragement as the dice roll.

Noise, noise and more noise.

If you have visited a casino, you may remember the constant assault of jangling slot machines encouraging people to keep playing and the excited shouts as players hit a jackpot. You may remember the ambient noise of the machines and the intensity of the players hoping to win that next jackpot.

But what happens when a fire occurs? The alarm sounds, but can anyone hear it? Just imagine the difficulty with all of that noise and intense concentration. How can we get the players attention to let them know a fire has started and they must evacuate?

Is it difficult to overcome the ambient noise? You bet. Is it even more difficult to convince the players to leave a winning slot machine? Absolutely.

Installing a fire alarm system in a casino often requires a great amount of creativity and a clear knowledge of the signaling requirements—audibility, intelligibility and visibility—of the National Fire Alarm Code, NFPA 72-2007.

From the standpoint of NFPA 101, Life Safety Code and most building codes, casinos fall into the category of an Assembly Use Group with more than 300 occupants. All casinos require protection with a complete coverage automatic sprinkler system. Generally, the building has a fire alarm voice communication system interconnected to the central security station of the casino.

The fire alarm system monitors the automatic sprinkler system for water flow and control valve closures. It also monitors alarm and supervisory signals from all other special suppression systems, such as kitchen hood suppression systems.

The designer and installer of the fire alarm system could use a number of scenarios to develop a code-compliant fire alarm and voice communication system in a casino. He or she could choose to use a public mode notification system. This would ensure that, when the fire alarm system responds to an alarm condition, all speakers would sound a temporal code 3 signal throughout the building with prerecorded messages and the option for officers at the security center to manually transmit voice instructions to the occupants.

The designer and installer of the fire alarm system also could choose another option that would use the positive alarm sequence option that section of the Life Safety Code, NFPA 101-2006 permits. Positive alarm sequence essentially allows the fire alarm system to sound an alarm at a constantly attended location. Once acknowledged by the operator, the fire alarm system can delay the general alarm throughout the building. During the delay, trained personnel may conduct an investigation to validate the source of the alarm. If the investigation exceeds three minutes, the fire alarm system initiates the general alarm. If, within the prescribed delay period, the investigators discover the source of the alarm signal does not warrant evacuation, they may reset the fire alarm system. However, if another initiating device sends an alarm signal during the investigation period, the fire alarm system immediately actuates the general alarm throughout the building.

The system also must provide a means to bypass the positive alarm sequence. This enables automatic or manual day, night and weekend operation. Using the positive alarm sequence feature will often meet the casino owner’s goal of ensuring a real emergency exists before completely evacuating the casino.

In addition, casino operators usually provide closed-circuit security cameras located strategically throughout the occupied areas of the building. They also provide trained security professionals in radio contact with the central security office who make continuous patrols throughout the buildings of the casino complex. These additional protection features, along with the security personnel staffing the central security office, help verify most reported alarm conditions.

No games for you

But how do we get enthralled guests of the casino to stop playing and leave the casino when a real fire situation exists? Simply shutting down the gaming machines when the fire alarm evacuation signal activates is an option. NFPA 72 makes specific provision to take any action that will improve life safety. By interfacing the operating power for the gaming machines through contacts controlled by the fire alarm system, a casino operator can make sure the guests will have no incentive to stay and play during a real fire alarm evacuation scenario.

Naturally, the designer and installer must make a special effort to minimize false fire alarms. By carefully selecting detection devices appropriate to the ambient conditions of each area, the designer and installer can significantly reduce the incidence of false alarms.

In fact, the designer and installer must make every effort to ensure the highest possible quality for the fire alarm installation. No casino operator will tolerate a system that operates unnecessarily. Nor will a casino operator want the liability of having a fire alarm system that does not operate when a real fire occurs.

Whenever a fire alarm system delays the general evacuation signal, a careful designer and installer will weigh all intervening protection factors before also deciding to delay the notification of the public fire department. At most casinos, the fire alarm system should not delay the alarm signal transmitted to the public fire department.

The other important design requirements of a casino notification system include the ability of the system to provide an alarm signal that occupants can clearly and understandably hear above the ambient noise levels. This involves both audibility and intelligibility. Typically, casino floors with slot machines and high density gaming tables will have ambient noise levels in the neighborhood of 85 dBA (decibels measured on the A-weighted scale).

Using additional visible signals in a casino may not provide additional protection due to the large number of competing visual signals. The designer and installer should remember that NFPA 72-2007 now requires the use of visible signals whenever the average ambient sound level exceeds 105 dBA. They also should remember that the total sound pressure level produced by combining the ambient sound pressure with all audible notification appliances operating must not exceed 110 dBA at the minimum hearing distance—in other words, as close as one can get to the source of the sound.

NFPA 72-2007 states, “in addition to the danger of exposure to a high sound level, long-term exposure to lower levels may also be a problem when, for example, occupants must traverse long egress paths to exit or technicians test large systems over extended time periods … The limit of 110 dBA has been set as a reasonable upper limit for the performance of a system. For workers who may be exposed to high sound levels over the course of a 40-year employment history, the Occupational, Safety and Health Administration has established a maximum permitted dose before a hearing conservation program must be implemented. A worker exposed to 120 dBA for 7.5 minutes a day for 40 years might be in danger of suffering a hearing impairment.” The level set by NFPA 72-2007 offers a conservative guide to make certain hearing loss will not occur as occupants evacuate or relocate during an alarm condition.

In the case of a casino with normally high ambient noise levels, the designer and installer of the fire alarm system must consider how to reduce the ambient noise to help ensure the occupants will actually be able to hear the alarm signal. The authority having jurisdiction often will approve a fire alarm system arranged to stop or reduce ambient noise, as long as it does so in a code-compliant fashion.

Generally, when a fire alarm system stops or reduces ambient noise, the system must produce a sound level at least 15 dBA above the reduced average ambient sound level or 5 dBA above the maximum sound level (having a duration of at least 60 seconds) after reduction of the ambient noise level, whichever is greater. The designer and installer must measure these levels 1.5 m (5 feet) above the floor in the system’s service area. The relays, circuits or interfaces necessary to stop or reduce ambient noise must meet the requirements of Chapter 4. The relays must be listed for fire alarm use and be properly monitored for integrity.

Finally, the code requires, voice communications systems shall be capable of the reproduction of prerecorded, synthesized or live (e.g., microphone, telephone handset and radio) messages with voice intelligibility.” Occupants must be able to clearly understand the messages the fire alarm system reproduces.

Casino fire alarm notification systems present a significant challenge. But the professional contractor will find that the code provides alternatives to creatively deal with those challenges.

MOORE, a licensed fire protection engineer, frequent speaker and an expert in the life safety field, is a co-editor of the current National Fire Alarm Code Handbook. Moore is a principal with Hughes Associates Inc. at the Warwick, R.I., office.


About the Author

Wayne D. Moore

Fire/Life Safety Columnist
Wayne D. Moore, a licensed fire protection engineer, frequent speaker and an expert in the life safety field, is a principal member and past chair of NFPA 72, Chapter 24. Moore is a vice president with JENSEN HUGHES at the Warwick, R.I., office. He c...

Stay Informed Join our Newsletter

Having trouble finding time to sit down with the latest issue of
ELECTRICAL CONTRACTOR? Don't worry, we'll come to you.