Published on August 8, 2022.

In Compliance

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


NFPA 101

Single-exit design in multistory apartment buildings  

Most multistory apartment buildings in the United States and Canada require two means of egress, which usually means two exit stairs for occupants to leave a building during a fire or other emergency. But there’s a push underway across North America to reduce that number to one exit stair, driven in part by global design and building trends. Multistory apartment buildings with a single exit stair already exist in countries around the world, and the approach is beginning to catch on here as well. Seattle’s building code, for instance, allows some buildings up to six stories to be served by one exit stair.

Proponents of single-exit design point to a number of reasons for eliminating the second exit from multistory apartment buildings. Having to design for just a single exit, they argue, can result in buildings with smaller, more flexible footprints that fit on smaller parcels of land, resulting in a more efficient use of space, lower building costs, and, at least in theory, more affordable housing for buyers or renters. The popularity of this approach in Europe and elsewhere is often cited as proof that the second stair is unnecessary and simply takes up rentable space, which in turn drives up associated costs. While there is undoubtedly a host of critical issues around affordable housing in much of the world, it’s doubtful whether eliminating an exit stair is a suitable approach to helping solve the problem.

A basic requirement of NFPA 101®, Life Safety Code®, is that every portion of a building includes two means of egress, with each egress consisting of exit access, exit, and exit discharge. This fundamental component of NFPA 101 serves two main purposes. The first is to provide an alternative route in the event that a fire or similar emergency blocks one of the means of egress. The 1946 Winecoff Hotel fire in Atlanta, Georgia, illustrated the deadly ramifications when a single exit stair becomes blocked—in that fire, 119 people lost their lives.

While there is undoubtedly a host of critical issues around affordable housing in much of the world, it’s doubtful whether eliminating an exit stair is a suitable approach to helping solve the problem.

The second purpose of two means of egress is that the design allows firefighters to set up and attack the fire from one of the exit stairs while occupants continue to use the other means of egress to exit the building. Firefighting operations require the exit stair door to be open, which allows smoke and heat to travel vertically. If other doors to that stair are open, the effects from the fire can compromise additional floors and put occupants on those floors at risk. Having an additional stair for occupants to use minimizes their exposure to smoke and heat. The 1980 MGM Grand hotel fire in Las Vegas, which killed 85 people, demonstrated how fatal the spread of smoke can be. Although the fire was contained to the first floor, the majority of the victims were located on the upper floors. A number of factors allowed the spread of smoke in that fire, but exit stairs with open doors were a contributing factor.

NFPA 101 contains exceptions to the base requirement of two means of egress. Most of the exceptions can be found in the occupancy chapters and are accompanied by a list of specific criteria that also need to be met. One example of this type of exemption, and perhaps the most relevant, allows for a single means of egress in an apartment building that is four stories or less. These buildings must meet a number of additional criteria, including a limit of no more than four dwelling units per story, the installation of an automatic sprinkler system throughout the building, a minimum one-hour fire resistance rating of exit access corridors, and a minimum half-hour fire resistance rated construction separating dwelling units. In Seattle, the building code allows a six-story building to have a single means of egress—provided a maximum of five of those stories are served by that means of egress—but in general many of the points highlighted in the Life Safety Code are also required by Seattle.

A major issue with proposals to eliminate the second means of egress—proposals that are based on practices found in Europe and elsewhere—is that they are being considered independent of related aspects of building safety. A building’s fire protection and life safety systems are referred to as “systems” because they contain many different components that must work together. Picking and choosing different approaches without an understanding or appreciation for how they can affect the whole will likely not result in a building that is truly safe. While a single means of egress is the norm in many European countries, so is the use of noncombustible building materials, along with more compartmentation inside the structure. In the United States, by contrast, traditional wood-frame construction is still commonly used—just one example of why applying a single aspect of the European approach to fire protection and life safety without altering any other requirements is flawed and risky.

Stories, a 13-story mixed-use wooden building recently constructed in Amsterdam, is designed with a single exit stair. The illustration at bottom shows different floor configurations built around the building's stair and elevator core. While the single-stair concept is attracting supporters in the United States—where almost all jurisdictions require buildings to have two exit stairs—experts caution that the approach isn't viable without also addressing occupant safety in the form of interior compartmentation, noncombustible building materials, and other fire safety measures. IMAGES COURTESY OLAF GIPSER ARCHITECTS, ©MAX HART NIBBRIG

Jurisdictions need to rethink their desire to amend a key component of building fire protection and life safety at the local level rather than through the proven codes and standards development process—the process that created the Life Safety Code in the first place. These kinds of changes need to be proposed, evaluated, and ultimately decided by the consensus process so that additional building modifications necessary for single-exit design can also be considered. Through the consensus code development process, we can maintain the minimum level of safety we have come to expect. 
—Valerie Ziavras is a technical services engineer at NFPA


The time delay between sprinkler actuation and fire alarm notification

Over the past several months, incidents have occurred in mercantile occupancies that have raised questions related to the timing of sprinkler actuation and fire alarm notification in the event of a fire, 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 the video I noticed the same types of comments from members of the public 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 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, except that the notification would have occurred after a delay of not more than 100 seconds. It’s likely that 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. 

—Shawn Mahoney, PE, is a technical services engineer at NFPA 


Automated and remote inspection and testing of sprinkler systems

A few years ago, remote inspections and automated testing were trends that had been gaining momentum in codes and standards and field application. Then, in the first half of 2020, when the COVID-19 pandemic was in its early stages and strict lockdowns were being enforced, these practices took off, propelled by the obvious possibilities they held for the safety community. The development of a proposed new standard, NFPA 915, Standard on Remote Inspections, also continued during this period. While the proposed NFPA 915 will apply broadly to any inspection or testing allowed by the authority having jurisdiction, there are already provisions in NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, that allow for inspections or testing to be conducted in an automated manner.

Automated inspection and testing can be a useful option, but it’s important to know what steps must be taken to ensure it is equivalent to a person being at the location. If a fire pump demonstrates an abnormal condition during a test, for example, what should the response be and how is the risk mitigated? NFPA 25 contains requirements to allow the use of technology for automated inspection and testing and the criteria to ensure it is equivalent to those conducted in person.

The first thing to address is where, or for which activities, automated inspection and testing can be utilized. NFPA 25 does not limit the use, provided automated inspection equipment can meet the intent of a required visual inspection and automated testing equipment can produce the same action as required by the testing requirements. Beyond that, the other criteria for automated inspection and testing must be met when this is utilized, and at that point it becomes a cost-benefit analysis for the stakeholders and primarily the building owner. Activities required at greater frequencies might present more of a benefit, while those required less frequently might see less of a benefit.

If automated testing is utilized, additional criteria must be met. Automated test devices must be listed for the purpose of the test being conducted unless they are not subjected to system pressure or are not integral to the operation of the system during a fire event. The equipment must be such that its failure does not impair the operation of the system unless that failure can be indicated by a supervisory signal to the fire alarm system. Similarly, any failure of a component or system to pass an automated test must result in an audible supervisory signal, and failure of automated inspection and testing equipment must result in a trouble signal. The monitoring and signals required ensure that instances where there are issues with the automated testing or inspection equipment or an unsatisfactory inspection or test result notification will be made and the situation can be remedied. The testing frequencies of NFPA 25 must be maintained regardless of the functionality of automated testing equipment, and a record of all inspection and testing must be maintained in accordance with the requirements that apply to all inspection and testing.

A benefit of automated inspection and testing is that personnel don’t necessarily have to be on site. However, certain circumstances may need to be addressed quickly and would require someone on site. This is specified for no-flow testing of fire pumps, which is a weekly or monthly requirement depending on the type of pump and the building it is in. The 2020 edition of NFPA 25 requires that when remotely monitored automated testing of the no-flow fire pump is being performed, qualified personnel must be able to respond to an abnormal condition within five minutes—essentially meaning that a qualified person must be on site. For the proposed 2023 edition of NFPA 25, which will be approved this summer, that timeframe will be changed to four hours. This additional time means that someone does not need to be immediately on site provided they can respond quickly enough to take the needed corrective action.

The use of technologies to perform automated inspections and testing will only grow. As it becomes more widely used, as building owners, service providers, and AHJs gain more experience, and as the use of automated inspections expands into other areas of fire protection and life safety with the future publication of NFPA 915, it is likely that the requirements will continue evolve, too. 

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

NFPA 70 + 70E

EV charging safety considerations for end users

You may have heard about the billions of dollars being spent on building an electric vehicle (EV) infrastructure in the United States. The National Electric Vehicle Infrastructure (NEVI) Formula Program has been established by allocating approximately $5 billion from President Biden’s Bipartisan Infra-structure Law, funding intended to create a national EV charging grid to help support the use of EVs across the country. While it is fairly common to see an occasional EV charger in our daily travels, it is likely that over the next several years EV chargers will start popping up like dandelions in the springtime. Over the next several years, as auto manufacturers move toward shifting their production from combustion engine vehicles to EVs, it is also likely that you may need to begin using EV chargers yourself. But as you reach for that handle to charge an EV, it is also important that you do it safely.

Within the scope statement itself, the National Electrical Code® (NEC®) calls for the “practical safeguarding of persons from hazards arising from the use of electricity,” and EVs are no exception. The scope of Article 625 Electric Vehicle Power Transfer System covers the electrical conductors and equipment connecting an EV to premises wiring for the purposes of charging, power export, or bidirectional current flow.


While the full installation of the system as a whole is vital to safety, there are a couple of key requirements intended to keep users safe while charging an EV. One requirement calls for a personnel protection system that protects users against electric shock during charging. Typically, this is achieved by manufacturers designing the internal circuitry of the EV charger to meet UL 2231-1 and UL 2232-2 standards. The other requirement provides ground-fault circuit-interrupter (GFCI) protection for all receptacles that supply power to EV chargers. Because EV chargers are often located in areas that are subject to moisture, it is crucial to have GFCI protection in place to protect against electric shock. Testing of any GFCI protection, at minimum based on manufacturers’ recommendations, is a means of ensuring it is working properly and ready to protect any individual who is using the EV charger when moisture is present.

While code requirements can define what must be incorporated into an installation to keep people safe, actions of the individuals utilizing EV chargers also weighs heavily on safety. In May, during National Electrical Safety Month, the Electrical Safety Foundation International (ESFi) highlighted EVs as part of its “Energy Resilience” theme and offered some safety tips for EV charger users. First, it is recommended that the newly purchased EV charging equipment has been tested and listed by a nationally recognized testing laboratory, such as UL or Intertek. It is also necessary to ensure the charger is installed by a qualified electrician who performs the installation based on NEC requirements. Additionally, it is important to be sure all charging of an electric vehicle is done in accordance with the charging equipment instructions. Look for physical damage to equipment, such as wear or damage to the charging cord or plugs. Pay special attention to public EV chargers where there is a high level of usage by multiple handlers, where excessive wear may take place faster than with private EV chargers at a home or business. Never use an EV charging cord that appears to be damaged or is showing exposed wiring.

As technology continues to advance, it is likely that EV charging will as well, in turn requiring a continued reevaluation of safety protocols. For example, in recent cycles the NEC has begun to incorporate interactive systems and bidirectional power where EVs themselves can be utilized to supply power to the premises wiring system. Wireless power transfer (WPT) has also been addressed within the NEC as a means of charging EVs. While wireless charging eliminates the need to plug in, which standard EV chargers require, it may pose additional safety concerns, such as the wireless interactivity between the charge station and the vehicle. Ongoing development of wireless-charging technology—such as the in-road wireless charging system currently being installed in Michigan—will likely require additional NEC modifications to ensure that these installations can be done safely.

Whatever roads EVs take us down moving forward, it remains paramount that we keep charging safety in the high-beams.

—Corey Hannahs is senior electrical content specialist at NFPA.