Published on June 1, 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 72 and the need to reduce nuisance smoke alarms

A tragic fire in a Philadelphia rowhouse on January 5 resulted in the deaths of 13 people. Investigators found that none of the smoke alarms within the upper unit, where the fire occurred, appeared to be working at the time of the fire. Three smoke alarms had been stuffed into a kitchen drawer, and another was found in a bedroom drawer. One alarm remained on the ceiling of a bedroom but did not include a battery. An additional alarm was found on the floor of another bedroom, also without batteries. I can only guess at the specific circumstances that led to these smoke alarms being disabled or removed, but history tells us that nuisance alarms are often involved.

One objective of Chapter 29 in NFPA 72®, National Fire Alarm and Signaling Code®, is to ensure that residential smoke detectors and alarms correctly detect hazardous conditions while minimizing nuisance alarms. This is important because nuisance alarms can lead to occupants disabling or removing smoke alarms from the ceiling if they become annoyed with the constant sounding. According to the 2021 NFPA report “Smoke Alarms in U.S. Home Fires,” almost three out of five home fire deaths were caused by fires in properties with no smoke alarms or smoke alarms that failed to operate—an indication of how crucial the presence of working smoke alarms is to life safety in the home.

Because of this, NFPA 72 paragraphs (4) and (5) address the placement of smoke alarms near stationary or fixed cooking appliances, which are recognized as the primary source of nuisance alarms. Prior to January 1, 2023, smoke alarms need to be equipped with an alarm silencing means, use photoelectric detection, or be listed for resistance to common nuisance sources from cooking if they are installed 10–20 feet (3–6 meters) along a horizontal flow path from cooking equipment. After January 1, 2023, all smoke alarms installed that same distance along a horizontal flow path from cooking equipment will need to be listed for resistance to common nuisance sources from cooking. If the 10-foot (3-meter) area of exclusion would prohibit the installation of a smoke alarm, then a smoke alarm can be placed as close as 6 feet (1.8 meters) from cooking equipment, if it is either listed for resistance to common nuisance sources from cooking or a photoelectric type smoke alarm.

The reason the requirements do not permit the use of an ionization-type smoke alarm near cooking appliances is that nuisance alarms caused by cooking activities occur more frequently with ionization smoke alarms than with photoelectric smoke alarms. The smoke alarms listed for resistance to common nuisance sources from cooking must be tested and listed in accordance with the 8th edition of UL 217, the 7th edition of UL 268, or subsequent editions. These listed alarms utilize multiple different sensors and algorithms to be able to differentiate between smoke caused by common cooking vs a fire.

Another source of common nuisance alarms is from steam from a shower. Because of this, paragraph (6) of NFPA 72 does not permit smoke alarms to be placed within 36 inches (910 millimeters) in a horizontal path from a door to a bathroom containing a shower or tub unless it is listed for installation near such locations.

It is important to note that there is more that goes into the placement of smoke alarms than just making sure they will operate in the event of a fire. They also need to be placed in a manner that will reduce the number of nuisance alarms—which will ultimately reduce the chances that an occupant may disable them—and allow the smoke alarms to operate as intended and reduce the chances of occupants dying in a fire. 
—Shawn Mahoney, P.E., is a technical services engineer at NFPA. 



Information signage requirements for sprinkler systems

The 2022 edition of NFPA 13, Standard for the Installation of Sprinkler Systems, includes important changes related to the information signs that accompany sprinkler systems.

NFPA 13 requires that systems include signs at various locations that provide hydraulic information as well as general information on the building and its use. This information forms the core of what’s known as the “basis of design,” which is determined at the time of design. While these design decisions are required to be documented in the planning and approval process, the original plans often become difficult to track down. Keeping a record of this information in the form of sprinkler system signage means it’s easier to access if changes are made to the water supply or to the building’s use, changes that may require a full evaluation of the sprinkler system. Questions often arise as to the difference between what is required for a newly installed sprinkler system and what’s required for existing systems installed under previous editions of the standard.

There are two kinds of information signs required by NFPA 13 for all newly installed systems: a hydraulic design information sign (or a pipe schedule design information sign, where applicable) and a general information sign. Systems using antifreeze are required to have a third type of sign detailing information about the antifreeze system. Most valves also require identification signs, but those are not discussed here.

Hydraulic design information signs have been required by NFPA 13 since the 1960s—nearly as long as hydraulically calculated systems have been permitted—and have remained largely unchanged. These signs must include the location of the design area or areas, size or number of sprinklers in the design area, discharge densities over the design area, required flow and residual pressure at the base of the riser, and other information. This concise summary allows for confirmation of the system demand and key design parameters at the time of installation.

A general information sign is similar in purpose to the hydraulic information sign but is intended to include even more detail about the system design basis and information relevant to the inspection, testing, and maintenance required by NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems. These were first required in the 2007 edition of NFPA 13. For the 2022 edition, this list now numbers 20 items and includes occupancy classification, commodity classification, presence of high piled or racked storage, maximum height of planned storage, the original main drain test results, the locations of auxiliary systems and/or drain connections, and more. This information is important to the building owner and occupants, inspectors, designers, and insurers when a review of the system criteria is needed due to changes in occupancy, storage array, or water supply.

Beyond the content of the signs, their location also needs to be considered. Hydraulic information signs must be placed at every system riser, floor control assembly, alarm valve, dry pipe valve, preaction valve, or deluge valve supplying the corresponding hydraulically designed area unless the authority having jurisdiction approves an alternate location. This is a significant change for the 2022 edition of NFPA 13, where each system riser and floor control assembly had not been previously specified. This change will result in many more hydraulic information signs than previously required. General information signs are required at each system control riser, antifreeze loop, and auxiliary system control valve.

It is worth noting that combining the hydraulic design information sign and the general information sign is permitted. Consolidating the signs reduces the required space for signage at valves or in valve rooms. These signs must be permanently marked, be of weatherproof metal or rigid plastic, and secured with corrosion-resistant wire, chain, or other approved means.

Existing systems are not exempt from information signs. The owner’s responsibilities section of NFPA 25 requires that information signs be located at the system control riser supplying an antifreeze loop, dry system, preaction system, or auxiliary system control valve. Signs are one of the items that must be visually verified during the annual inspection of sprinkler systems. The information required by NFPA 25 is not as substantial as that required by NFPA 13, and it is not necessary for a system to have both the information sign required by NFPA 25 and the general information sign required by NFPA 13. The information sign required by NFPA 25 is only intended for systems installed prior to the 2007 edition of NFPA 13.

The presence of information signs does not in and of itself make a sprinkler system any more reliable. The signs do, however, provide the means to quickly determine if the water supply is still sufficient or if changes in the occupancy or use of the building require a design analysis. 

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


NFPA 101

‘Last resort’: The Life Safety Code and fire escape stairs

In the wake of a number of recent fires, questions have been raised as to the role of fire escape stairs in mid- and high-rise apartment buildings. Although fire escape stairs are often seen as an acceptable component in a means of egress, NFPA 101®, Life Safety Code®, which governs the protection of occupants from the effects of fire, permits the use of exterior fire escape stairs in the required means of egress only as a last resort.

Fire escape stairs are generally constructed of noncombustible materials and attached to the outside of a building—think of the classic iron fire escapes bolted to the facades of older structures across the country. They are typically accessed either via a window or door that opens onto a platform. They do not meet the more restrictive requirements of an outside stair, which is a stair that meets the same dimensional criteria as an inside stair but is located on the outside of the building. An outside stair also has additional protection requirements to minimize the risk that fires occurring inside of a building will affect the usability of the stairs.

The use of fire escape stairs is extremely limited; they are only permitted for use on existing buildings of certain occupancies, such as existing hotels, dormitories, and apartment buildings. A new fire escape stair can be added to an existing building only to correct an egress deficiency and when the authority having jurisdiction has determined that the construction of an outside stair is not possible. There is no building height limitation in NFPA 101 for the addition of a new fire escape to an existing building.

While outside stairs are preferred over fire escape stairs, the Life Safety Code recognizes that, at least for some existing buildings, an outside stair may be impractical. Examples include when the space between the building and property line is too small to accommodate a stair meeting the dimensional requirements of an outside stair, or where the stairs are over a sidewalk or alley that cannot be permanently blocked by the construction an outside stair would require.

The preference for outside stairs over fire escape stairs can best be explained by comparing the requirements of the various components, starting with the dimensions. An outside stair, like an interior stair, is required to be at least 44 inches (1,120 millimeters) wide when serving fewer than 2,000 people, whereas a fire escape stair is required to be at least 22 inches (560 millimeters) wide when it serves more than 10 occupants. For a fire escape stair serving more than 10 occupants, the riser height can be no more than 9 inches (230 millimeters) and the tread depth must be at least 9 inches (230 millimeters). For a new outside stair, the maximum riser height is 7 inches (180 millimeters) and the minimum tread depth is 11 inches (280 millimeters).

The second major difference between an outside stair and a fire escape stair are the separation and protection requirements. An outside stair is required to be separated from the interior of the building by construction with the same fire resistance rating that would be required for an enclosed stair. Doors and windows are required to be protected and need to be fixed or self-closing. These requirements are intended to prevent fire and smoke from affecting the outside stairs. Contrast that with the protection requirements for fire escape stairs, which only require that they be exposed to the smallest possible number of window and door openings. Those openings are required to be protected if they meet certain conditions. The fire escape stairs are not required to be separated from the inside of the building, meaning it is possible for fire or smoke from lower floors to render the stairs impassable.

Additionally, since fire escape stairs are used so infrequently, they may not be maintained as well as they should be, and general upkeep could be neglected. In colder climates, snow and ice may make them unusable. In general, occupants find them challenging to navigate. This could result in even slower travel under emergency conditions.

The minimum dimensional criteria, as well as the separation and protection requirements, create significant differences between outside stairs and fire escape stairs. In some existing buildings, though, fire escape stairs may be the only viable egress option in an emergency. For new buildings, however, and when considering the replacement of an existing fire escape stair, all possible alternatives must be explored. 

—Valerie Ziavras is technical services engineer at NFPA.

NFPA 70 + 70E

2023 NEC discussions include proposals related to electric shock drowning

The phenomenon of electric shock drowning, or ESD, can occur when a person enters a body of water, including a pool or marina, that contains enough AC current to disable them and result in drowning. In recent years, a steady stream of news stories from around the country involving ESD deaths has underscored the need to regard this hazard as a serious concern around boats, docking facilities, and marinas.

ESD does not result from contact with electrical equipment or electrical conductors—rather, it’s a phenomenon that can occur where boats in water are connected to shore power electricity, with the boats emitting a low-level AC current that travels through the water. If a person enters that water, the AC current can impact the body with sufficient force to cause skeletal and/or muscular paralysis, rendering the victim helpless and putting them at risk of drowning. Higher levels of AC current in the water can also result in electrocution. ESD tends to occur more frequently in freshwater environments such as lakes and ponds than in salt water. ESD deaths are difficult to track and may often go unreported, and postmortem examinations may not reveal signs that electricity was involved in the fatality. Even so, experts estimate that scores of ESD deaths occur nationwide every year.

ESD isn’t specifically addressed in NFPA 70®, National Electrical Code® (NEC®), but it continues to have a significant impact on recent changes to the code. A number of NEC requirements address the ESD hazard, including some important changes made to the 2020 edition. One of those addressed both ground-fault protection of equipment (GFPE) and ground-fault circuit interrupter (GFCI) protection in Article 555, Marinas, Boatyards, Floating Buildings, and Commercial and Noncommercial Docking Facilities. With cumulative effects of leakage current causing excess tripping of 30 milliampere GFPE devices, changes were made to code language that increased GFPE current settings not to exceed 100 milliamperes on feeders and branch circuits. This change helped facilitate more dependable power for marinas and docking facilities. However, individual branch circuits feeding single shore powered receptacles must have individual GFPE devices set to open at currents not exceeding 30 milliamperes. Coincidentally, this requirement matches main breaker settings in boats manufactured after July 31, 2017.

New 2020 NEC language also required marinas, boatyards, and docking facilities that have more than three receptacles supplying shore power to boats to have a leakage current measurement device available on site. This device would allow facility operators to isolate and notify boat owners of leakage current so repairs could be made by a qualified person, thus helping to eliminate a potential ESD risk.

Additionally, Section 555.9 was added to the code. This called for boat hoist outlets not exceeding 240 volts that are installed at dwelling unit docking facilities to have GFCI protection for personnel. This requirement was intended for marine areas that include residences with private docks, locations where ESD hazards may be overlooked. These homes don’t always have shore power, but they may have electrically powered boat hoists that can introduce low-level AC current into the water.

Language was also added to the 2020 NEC addressing signage. Installing permanent safety signs around marinas, boatyards, and docking facilities gives notice of electrical shock hazard risks to persons within those areas. The code making panel felt that signs should say more than “No Swimming,” however, since some people may not take that warning seriously and swim anyway. Signs should now say: “WARNING–POTENTIAL SHOCK HAZARD–ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER.” To further aid in preventing ESD, docking facilities were added in the 2020 NEC, joining marinas and boatyards as potential ESD hazard areas covered in section 555.10.

Although still in the development stage, number of ESD-related changes have been suggested for the 2023 NEC. One proposal would require emergency electrical disconnects within sight of the marina power outlets, which would allow bystanders to quickly de-energize power to a docked boat and safely release a person who may be suffering an electric shock. Additionally, a proposed requirement would add equipotential planes and bonding of equipotential planes that could help mitigate step and touch voltages for electrical equipment that supply power to the equipment. There has also been a proposal that would require modified, repaired, or replaced equipment to be updated to current provisions due to exposure to harsh marine environments.

Marinas, boatyards, and docking facilities will always be challenging, dynamic environments, in part because vessels in various degrees of electrical repair are constantly moving through these areas. That’s also why water-borne AC current will remain a hazard in those environments. Recent changes to the NEC have made marinas, boatyards, and docking facilities safer by regulating electrical requirements, and future editions promise to further address ESD hazards.

For more information on the ESD hazard, visit

—Dean Austin is senior electrical content specialist at NFPA.