Published on December 2, 2022.

CODES & STANDARDS
In Compliance

A quarterly overview of timely topics related to major NFPA codes and standards, written by NFPA engineers and other technical staff members 

BY JONATHAN HART, BRIAN O'CONNOR, VALERIA ZIAVRAS, AND DEAN AUSTIN
 

NFPA 72

Understanding emergency responder communication enhancement systems

In recent months, fires have occurred in mercantile occupancies that have raised questions on the timing of sprinkler actuation and fire alarm notification, a fundamental aspect of NFPA 72®, National Fire Alarm and Signaling Code®.

One example was captured in a video—shot on a smart phone and widely shared on social media—of a fire that started in a retail store. The video was taken by an occupant inside the building prior to egressing and shows sprinklers operating and controlling the fire. The video was shared among multiple social media platforms, and everywhere I saw it I noticed the same types of comments from viewers who may not understand how fire protection and life safety systems operate. The comment I saw the most was, “Why isn’t the fire alarm going off if there is a fire?”

The answer is that the store's fire alarm system might not have been required to provide occupant notification based on sprinkler actuation. NFPA 72 permits up to a 100-second delay between sprinkler waterflow and occupant notification; it is likely that the fire alarm did in fact notify the occupants in that video, with notification occurring after a delay of not more than 100 seconds. It’s possible the video was taken before that delay was over.

The allowance for a 100-second delay before the actuation of alarm notification appliances is broken down into two requirements. The first requirement is related to the waterflow initiating device and found in Section 17.13 of NFPA 72. Subsection 17.13.2 requires that the waterflow initiating device activate within 90 seconds after a flow occurs that is equal to or greater than the flow from a single sprinkler of the smallest orifice size. The 90-second allowance exists to reduce the number of nuisance alarms caused by water flow that can occur from pressure surges in the water supply system. The delay provides added assurance that the water flow in the sprinkler piping is in fact sustained flow from a sprinkler, and not just the result in a change in pressure. This delay can be created within the flow switch itself, or it can be accomplished with the use of a retarding device such as a retard chamber when using a pressure switch.

The second part of this delay is found in subsection 10.11.1. This section requires that the actuation of alarm notification appliances at the protected premises occurs within 10 seconds after the activation of the initiating device. This requirement exists to ensure that the operation of the notification appliances occurs within a timely manner after a fire has been detected. Between those two requirements in subsections 17.13.2 and 10.11.1, NFPA 72 permits up to a 100-second delay between the initial waterflow from a sprinkler and the actuation of the notification appliances within the building.

In addition to this allowance intended to reduce the number of nuisance alarms, allowances exist to delay the actuation of notification appliances for other initiating devices with the use of a presignal feature or positive alarm sequence, though both of these require a detailed response plan and approval from the authority having jurisdiction.

The next time someone asks you a question about the timing of sprinkler waterflow and fire alarm notification, remember that NFPA 72 permits the delay in the actuation of fire alarm notification appliances. This timing is engineered into the operation of the systems, and it exists to ensure that they function as effectively as possible.

Jonathan Hart is technical lead, Fire Protection Engineering, at NFPA.

 

 

NFPA 13

The growing importance of fire suppression in data centers

Remember the days when dropping your phone in the water or spilling coffee over your laptop meant the device’s data was lost forever? Those days are gradually disappearing, fortunately—the rise of cloud computing means your information is backed up on servers in vast data centers. And that growth continues: recent reports project the global data center market will grow by $615 billion between now and 2026.

With all of this expanding infrastructure, it’s important to protect these buildings from fire and its associated hazards. This is done through several different fire and life safety design decisions, most notably the installation of sprinkler systems. NFPA technical staff often receive questions regarding whether sprinkler systems need to be installed in these facilities.

Simply put, sprinkler systems are essential to the protection of life and property from the effects of fire. However, some stakeholders in the data center sector have expressed concerns over the potential of an accidental discharge of a sprinkler or water damage from corroded piping in buildings protected by sprinklers. These concerns are amplified in data centers, where the equipment can have high monetary value and the repercussions of lost data can be severe.

This begs the question of how data centers are required to be protected. Are these buildings required to have sprinkler systems installed, or can we replace them with another type of automatic fire protection system, such as a gaseous or water mist system? Ultimately the answer to this question is found in your local fire or building code as well as other locally adopted codes and standards.

Several factors come into play when determining whether sprinklers are required, including occupancy, construction type, stories in height, and floor area. Looking at the specific standards that would apply, NFPA 13, Standard for the Installation of Sprinkler Systems, contains requirements on how to install sprinklers systems, while NFPA 75, Standard for the Fire Protection of Information Technology Equipment, contains specific requirements on how to protect buildings and areas containing information technology equipment such as data centers.

The requirements in NFPA 75 state that if the rest of the building has sprinklers installed, then sprinklers need to be installed in the information technology equipment room as well. It goes on to require that if the building is not sprinklered, then some sort of fire suppression system, whether a gaseous or water mist system, still needs to be installed to protect that room and equipment. NFPA 75 also requires a sprinkler system or a gaseous fire protection system to be installed under the raised floor if the area below the raised floor contains certain combustible material.

Even if a sprinkler system is required to be installed throughout the building, there is still a design path that might permit the omission of sprinklers in lieu of another equivalent protection method. This allowance comes from NFPA 75 and states that there is a choice between one of two permitted fire protection approaches. One option is the prescriptive approach, where the area would need to comply with the written requirements of NFPA 75. The other option would be to develop a performance-based design. With this option, a few rules need to be followed, first and foremost that the performance-based design needs to provide equivalent performance to the prescriptive requirements of NFPA 75. This is usually done by developing performance criteria to meet. Additionally, a risk assessment needs to be completed, and the individual conducting the performance-based design needs to be qualified. With performance-based approaches, it is important to have open communication with your authority having jurisdiction—in this case, that can include the insurance agency or the owner and is not limited to the local fire code official—to ensure approval. AHJs can also require a third party to review the design once it is completed.

While water is a great fire suppression agent, it can be damaging to information technology equipment. This is often the motivation behind trying to omit sprinklers from these areas. While it may be difficult to develop a performance-based design that is equivalent to sprinkler protection, there are sprinkler design options in NFPA 13 that will minimize the chances of accidental discharge or leaking pipes. Preaction sprinkler systems, either single- or double-interlock, can be used to limit that potential for water harm due to accidental discharge resulting from a damaged sprinkler. Piping can have increased pitch, additional auxiliary drains can be provided, and thorough inspection, testing, and maintenance programs can be implemented to limit the potential for corrosion issues.

Precautions to reduce the risk of accidental water discharge can also be taken, including locating sprinkler piping above aisles rather than the equipment to limit exposure to leaks, installing cages on exposed sprinklers to reduce the potential for damaged sprinklers, and reducing the number of piping joints in the system to minimize the number of potential leak points. Of course, the installation of another extinguishing system, while perhaps not eliminating the need for sprinklers, can also greatly limit the potential for water discharge in the event of a fire if it is able to effectively suppress or extinguish a fire in its incipient stage before sprinkler activation.

Data centers are an important part of global information infrastructure and need to be protected properly. NFPA 75 and NFPA 13 work together to ensure that appropriate protection systems are installed to ensure not only the property protection for these facilities but the safety of personnel.  

Brian O’Connor is a technical services engineer at NFPA.

 


 
NFPA 101

A Thai nightclub fire underscores assembly occupancy requirements

On August 5, a fire broke out at the Mountain B nightclub in southeastern Thailand during a live music performance, killing at least 22 people and injuring 25. It was an all-too-familiar scene; many of the details that have emerged about the blaze are eerily similar to the Station nightclub fire that occurred in 2003 in Rhode Island, which killed 100 people and injured 230. In both instances, highly combustible interior finishes and blocked exits were believed to have played important roles in the fast-spreading fires and the resulting fatalities. The Station fire led to a number of changes to NFPA 101®, Life Safety Code®, while also reiterating the importance of requirements for interior finishes and means of egress for assembly occupancies.

In both events, acoustic material is believed to have been a major contributing factor in the rapid spread of the fires. While there are still many unknowns related to the recent fire in Thailand, numerous reports mention the presence of flammable acoustic material in the club. The acoustic material used in parts of The Station nightclub did not comply with the interior finish requirements for assembly occupancies. In the Life Safety Code, the requirements for interior finishes are the same for new and existing assembly occupancies. In general assembly areas with an occupant load of 300 or fewer, ceiling and wall materials must be Class A, B, or C. In general assembly areas with an occupant load of more than 300, and in corridors and lobbies, interior wall and ceiling finishes must be Class A or B; Class C interior wall and ceiling finishes are permitted if the building is sprinklered. In enclosed stairs, interior finish materials must be Class A, and Class B is permitted if the building is sprinklered. Cellular and foamed plastic materials are prohibited from use as interior finishes unless they meet certain criteria using large-scale tests such as NFPA 286, Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth.

The classification is based on performance of the material when tested in accordance with ASTM E84 or UL 723. For new materials, both the flame spread index and smoke developed index are considered, whereas for existing materials only the flame spread index is taken into account. Alternatively, the material may be tested in accordance with NFPA 286; as long as it meets the criteria outlined in 10.2.3.2 of NFPA 101, it can be used wherever a Class A material is permitted. The acceptance criteria include limitations on the spread of flames; a peak heat release rate of less than 800 kW; and for new installations, the total volume of smoke released throughout the test cannot exceed 1,000 square meters.

Another contributing factor in the deadly Thailand fire was the availability of exits. In both the Mountain B and Station fires, one of the doors to the outside was blocked for use by occupants to allow the band to have their own separate entrance/exit. This runs counter to one of the fundamental components of the Life Safety Code, which is the concept of free egress. Prohibiting people from entering the building via a door is one thing, but not allowing occupants to exit the building via the nearest door is unacceptable. Additionally, NFPA 101 prohibits the means of egress for assembly occupancies from going through hazardous areas such as kitchens, storerooms, closets, stages, and platforms.

There are also requirements related to the size of a main entrance/exit, where one exists, in assembly occupancies. History has shown that occupants tend to exit a building the way they entered, even if another exit is closer. The main entrance/exit provisions are intended to prevent crowd crush situations. In new assembly occupancies that are dance halls, discotheques, or nightclubs, or that have festival seating, the main entrance/exits must be wide enough to accommodate two-thirds of the total occupant load. For all other new assembly occupancies and existing assembly occupancies, the main entrance/exit needs to be sized to accommodate at least half the total occupant load. The main entrance/exit requirements for certain types of new assembly occupancies was increased from half to two-thirds the total occupant load due to a crowd crush event during The Station nightclub fire.

Another way the Life Safety Code strives to reduce the risk of crowd crush is by requiring trained crowd managers. All assembly occupancies, with the exception of certain occupancies used exclusively for religious worship, are required to have at least one trained crowd manager. Depending on the total occupant load, additional crowd managers may be required. Typically, there should be one crowd manager for every 250 occupants. Prior to the 2006 edition, crowd managers were only required for assembly occupancies with occupant loads of more than 1,000. After The Station nightclub fire, the Life Safety Code was changed to require at least one crowd manager for all assembly occupancies. Within two minutes of the fire starting at The Station nightclub, a crowd crush developed at the main entrance/exit, making it impassable. The crowd manager’s responsibilities include understanding crowd management and methods of evacuation, being familiar with the facility evacuation plan and with the emergency response procedures, and understanding procedures for reporting emergencies.

While the cause of the recent fire at Mountain B is under investigation, The Station nightclub fire was caused by pyrotechnics. To reduce the risk of open flames or pyrotechnics starting a fire in an assembly occupancy, they are prohibited unless certain conditions are met. In order for pyrotechnics to be used on stage before proximate audiences, precautions to prevent ignition of any combustible material, satisfactory to the authority having jurisdiction, must be met, and the use of the pyrotechnic device must comply with NFPA 1126, Standard for the use of Pyrotechnics Before a Proximate Audience.

As we have seen countless times, fires in assembly occupancies, particularly nightclubs, can result in a high number of fatalities. By carefully considering the use of open flames and pyrotechnics, we can eliminate potential ignition sources in these types of occupancies. Additionally, ensuring the interior finish requirements for assembly occupancies are met can help slow the spread of fire. Fires in an assembly occupancy have the added risk of leading to a crowd crush event. Compliance with the means of egress and crowd manager requirements will help reduce the risk of crowd crush events during emergency situations.

Valerie Ziavras is technical services engineer at NFPA.

 


 
NFPA 70 + 70E

More on the NEC and the Proliferation of electric micromobility devices

Recent discussions around electric micromobility devices, such as e-bikes and e-scooters, have left a lot of people rather charged up. Proposed changes by the New York City Housing Authority (NYCHA), for example, would prohibit residents and guests from keeping e-bikes and e-scooters in NYCHA apartments or in the buildings' common areas. Delivery workers in the city have raised concerns that such a ban would adversely affect their livelihoods, since charging the e-bikes they use for deliveries would no longer be possible in their homes.

Big cities aren’t the only places where authorities have moved to ban e-bikes and e-scooters from buildings. Mackinac Island, a small vacation island in northern Michigan, has become well-known for regulating the means of transportation that are permitted on the island. Since 1901, automotive transportation has been banned, leaving most travel to be done on foot, by bicycle, or by horse and carriage. Not long ago, island authorities banned e-bikes within certain buildings and have further prohibited the use of e-bikes that have functional throttles when traveling around the island. (For an overview of the safety hazards associated with electric micromobility devices and the regulations proposed to address those hazards, see “Full Throttle,” the feature story that appeared in the fall 2022 issue of NFPA Journal.)

Improving e-bike and e-scooter safety is providing much of the momentum behind these changes. In 2022 alone, the New York City Fire Department (FDNY) has reported investigating 99 fires related to lithium ion batteries used to power e-bikes, fires that have resulted in two deaths and 37 injuries. A fire in December 2021 killed a New York City man who was running a business charging e-bikes in his residence; two teenagers narrowly avoided injury in the same fire by shimmying down a pipe mounted to an exterior wall of the building. Over the summer on Mackinac Island, an e-bike battery exploded and melted and exposed the homeowner and firefighters to smoke inhalation. If we consider these kinds of events on a scale that accounts for the number of people living in multifamily buildings such as those run by the NYCHA, the potential for many victims increases rapidly.

While there are no specific codes in place for the charging of e-bikes or e-scooters themselves, there are portions of codes, including NFPA 70®, National Electrical Code®, that can help people be safer while doing so. Electricity is necessary to charge e-bike batteries, meaning the battery being charged and the device charging the battery can be potential fire hazards. One aspect that is sometimes overlooked is that the structural wiring in the building can be a risk. Ensuring that the electrical infrastructure in the building is properly installed and capable of delivering electricity for safe charging is where the NEC comes into play. If we consider the deadly NYC fire that killed the man who was charging e-bikes out of his residence, overloading of the circuit may have been part of the issue. When multiple e-bikes are being charged at once, the load on the circuit supplying power for charging increases. The NEC requires that the structural wiring and overcurrent protection for circuits be rated for the load being served, but it would be hard to anticipate the load of multiple e-bikes being charged for business needs in a person’s residence.

Another scenario that could have compounded the imposed load on the circuit is that it was a continuous load. The NEC defines a continuous load as one where the maximum current is expected to continue for three hours or more and requires any continuous loads to be factored in at 125 percent. As an example, a 20-amp circuit is only permitted to be loaded to 16 amps when continuous loads are involved (16 amp continuous load x 125 percent = 20 amps). With e-bikes being charged for over three hours and multiple e-bikes being charged simultaneously, the circuit could have easily been highly overloaded, which could have begun degradation of the wiring, causing it to eventually break down and become a possible ignition source.

Another area that must be considered around e-bike charging safety is the product itself. Consumers should be sure that they are purchasing a high-quality product that has been listed by a standard such as UL 2849 Standard for Electrical Systems for eBikes, which examines the electrical drive train, battery, and charger system of the device. Part of the charger system evaluation is the plug-in charger itself. It is important for consumers to understand that the charger that comes with the e-bike is what gets tested as part of the listing and therefore is the only charger that should be utilized. Buying an aftermarket charger from another manufacturer could likely invalidate the listing of the e-bike and may contribute additional risk of a fire due to compatibility not being tested between the e-bike and the charger. There are many products out there that may be noted as compatible with an e-bike, but they may not be listed by UL 2849 to work with a specific e-bike.

The importance of using e-bikes and products that are listed was echoed in July when Heather Mason, president of the National Bicycle Dealers Association, encouraged their vendors and suppliers to certify their e-bikes to UL 2849. “The bicycle industry needs to take immediate action,” Mason stated at the time. “After extensive consultations with experts in the field, e-bike and e-scooter lithium-ion battery safety is a large and immediate subject that we need to act on now. The advisement statement we have prepared for retailers takes the interest of e-bike continued growth within the industry and safety for all. If we do not address the core issue, we may see this propel to something beyond our control.”  

With the recent proposed bans on e-bikes and e-scooters receiving a lot of attention, it is important to consider that the authorities proposing these changes are doing so with public safety in mind. When improper and unsafe charging of e-bikes takes place, tragedy can follow. People who use e-bikes should continue to learn about the intricacies involved in safe charging, for their own safety and their neighbors' safety as well.

Corey Hannahs is senior electrical content specialist at NFPA.