National Fire Protection Association (NFPA)'s Blog, page 6

New RFP Open, Due March 10th for FPRF Project: Evaluation of Electrical Conductors in Thermal Insulation: Literature Review, Gap Analysis & Development of a Research Plan

The Fire Protection Research Foundation is seeking proposals to identify a project contractor for a new project to determine the minimum level of safety and develop an assessment method for small branch circuit wiring installed in thermal insulation envelopes required by current building and energy codes. This phase of the project includes a literature review, gap analysis and development of a research plan to address the knowledge gaps which describes any additional modeling and/or testing needed. As background, during the last two revision cycles of NFPA 70®, the National Electrical Code (NEC®), proposed changes to add new conductor sizes have not achieved the necessary consensus of the Code-Making Panel (technical committee). These proposed changes have sought to add conductor sizes 16 AWG copper and 14 AWG copper-clad aluminum with their associated ampacities to Section 310.3(A) and two of the most frequently used ampacity tables in the NEC, Tables 310.16 and 310.17. Because the current product certification standards for the most widely used wiring methods do not contain testing requirements for thermal insulation impact, concerns have been raised that thermal insulation required by modern building and energy codes can adversely impact the performance of electrical conductor insulation. While the current discussion in the NEC® development process is focused on two specific conductor sizes, the technical committee needs the requisite information to make an objective assessment on whether the minimum level of safety can be achieved by adding new conductor sizes and materials to the Code. The guiding principle for this assessment is means by which the technical body can determine if the objective of 310.14(A)(3) is met. There is a need to provide methodology by which any conductor can be assessed to meet the general requirement provided above. Since the electrical industry still needs additional information on small branch circuit wiring installed in thermal insulation envelopes, the Research Foundation has initiated a project to address this issue through a literature review, gap analysis and development of a research plan. The open RFP seeking a contractor for “Evaluation of Electrical Conductors in Thermal Insulation: Literature Review, Gap Analysis & Development of a Research Plan” project is available here or on the Foundation’s website. Instructions on how to respond are included in the RFP. Please submit your proposal to Jacqueline Wilmot by March 10, 2023, at 5p.m. ET. 

The Hazard of Mixing Chemicals

We have all heard there are chemicals that we cannot mix together. Even at home, mixing chemicals like bleach and vinegar can create chlorine gas. Have you ever thought about this on a larger scale though? What happens when incompatible mixtures combine at manufacturing or storage facilities? In a small Kentucky town last month, three people were severely injured and one killed in an explosion. It all started when a waste company began pumping sludge out of a local plant. The sludge mixture combined with some used cooking oil that was already in the tank and exploded. The sludge, mixed with oil, caused a chemical reaction that resulted in an explosion that jettisoned the tank through an exterior wall and two interior walls. In my personal experience, I have seen reactions happen in containers that were thought to be considered empty. I have seen something as simple as drums of cleaning agents mixed together that created an incompatible mixture that reacted and started to melt a 55-gallon (208-Liter) drum. On a much larger scale, in May 2019, a chemical explosion occurred at a facility in Waukegan, Illinois, causing multiple deaths, injuries, and damage to multiple buildings. This was caused by the mixing of chemicals from a misidentified drum, where the reaction released flammable hydrogen gas into the building. How to stay safer As we know, this is not a new issue, but there are many things that we can do to ensure that we are not mixing incompatible materials, and NFPA® codes and standards give us a lot of guidance.  “Information on incompatible materials can be found in safety data sheets or manufacturers’ product bulletins. This is always the first place that you want to look when working with chemicals.  If you look in the 2022 edition of NFPA 400, Hazardous Materials Code, you will see that in Annex A, information on incompatible materials can be found in safety data sheets (SDS) or manufacturers’ product bulletins. This is always the first place that you want to look when working with chemicals. There are also many materials that are not compatible with water, especially combustible dusts. This causes an issue when there is a possible fire. In the 2020 edition of NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids, under Annex A.3.3.55, water-incompatible materials are classified as those that dissolve in water or form mixtures with water that are no longer processable—for example, sugar. Although water is an effective extinguishing agent for sugar fires, the sugar dissolves in the water, resulting in a syrup that can no longer be processed through manufacturing equipment. A similar situation exists with flour. When mixed with water, it becomes dough. These materials are candidates for extinguishing systems that use media other than water until the damage potential of the fire approaches the replacement cost of the process equipment. (Learn more about clean agent fire suppression systems in this blog.) Water-reactive materials, which are typified in Annex A.3.3.56 of NFPA 654, also represent a very special fire protection problem. The application of water from fixed water-based extinguishing systems or by the fire service without awareness of the presence of these materials could seriously exacerbate the threat to human life or property. For example, many chemicals form strong acids or bases when mixed with water, thus introducing a chemical burn hazard. Additionally, most metals in the powdered state can burn with sufficient heat to chemically reduce water-yielding hydrogen, which can then support a deflagration. These types of materials should be handled very carefully. Even small quantities of water usually make matters worse. It’s also important to remember that if incompatible chemicals are mixed, there is a potential for off-gassing. In an incident in March 2022, a worker was injured after being exposed to a toxic gas that was produced after two chemicals were mixed. This incident involved incompatible mixing with an oxidizer. Oxidizers are incompatible with many chemicals or other materials. It is essential to follow all storage and handling procedures to prevent conditions that might cause emergencies, such as a fire or explosion. Annex G.6.2 in NFPA 400 reviews the compatibility of dealing with oxidizers. Remember that you should always know what you have on site. Ensure that you have a site plan outlining what is at your location and your emergency plans, and ensure those who could be affected by chemicals are properly trained. When planning, make sure to check out NFPA 1660, Standard for Emergency, Continuity, and Crisis Management: Preparedness, Response, and Recovery. For more information on hazardous materials, reference NFPA 400.

Mobile Energy Storage Systems

Mobile energy storage systems are being deployed in jurisdictions around the world, and—as demonstrated by a 2023 New Year’s Day mobile energy storage system fire—accidents can happen. We want to make sure communities are prepared for when these systems are deployed in their backyard. This blog will outline key considerations for mobile energy storage systems. To see the full requirements, check out the latest edition of NFPA 855, Standard for the Installation of Stationary Energy Storage Systems.What is a mobile energy storage system? An energy storage system (ESS) is a group of devices assembled together that is capable of storing energy in order to supply electrical energy at a later time.A mobile energy storage system is one of these systems that is capable of being moved and typically utilized as a temporary source of electrical power. In practice, this is often a battery storage array about the size of a semi-trailer. Mobile energy storage systems can be deployed to provide backup power for emergencies or to supplement electric vehicle charging stations during high demand, or used for any other application where electrical power is needed.While there are various types of ESS and many battery technologies, this blog will focus on the most prevalent type—lithium-ion battery energy storage systems. Many of these requirements apply to any type of mobile energy storage system; see NFPA 855 requirements for details on other technologies.When does NFPA 855 apply to mobile energy storage systems?The scope of NFPA 855 states that it applies to “mobile and portable energy storage systems installed in a stationary situation.” It also goes on to mention that the storage of lithium-ion batteries is included in the scope of the document.The application section then limits the application of the standard to certain-sized mobile energy storage systems. For all types of lithium-ion batteries, the threshold is 20 kWh (72 MJ) before the requirements of NFPA 855 apply. For batteries in one- and two-family dwellings and townhouse units, that threshold is reduced to 1 kWh (3.6 MJ). For more information on residential ESS requirements, check out our previous blog on that topic.When looking at how a mobile energy storage system works, we break its use down into three phases: the charging and storage phase, the in-transit phase, and the deployed stage. This is how I’ll break down the requirements as well.Charging and storageWhen charging and storing a mobile energy storage system, the requirements are relatively straightforward. The system should be treated as a stationary system as far as the requirements of NFPA 855 go. These requirements will vary based on whether the system is being stored indoors, outdoors, on a rooftop, or in a parking garage.In-transitWhile a mobile energy storage system is in transit from its normal charging and storage location to its deployment location, it typically travels on roads that are governed by the governmental transportation authority (in the US, that would the Department of Transportation). However, when the mobile energy storage system needs to be parked for more than an hour, it needs to be parked more than 100 ft (30.5 m) away from any occupied building, unless the authority having jurisdiction (AHJ) approves an alternative in advance. Deployment documentsBefore a mobile energy storage system is deployed, it needs to be approved by the AHJ, and a permit must be obtained for the specific use case. The permit application must include the following items:Mobile Energy Storage System Permit Application Checklisto Information for the mobile energy storage system equipment and protection measures in the construction documentso Location and layout diagram of the area in which the mobile energy storage system is to be deployed, including a scale diagram of all nearby exposureso Location and content of signageo Description of fencing to be provided around the energy storage system and locking methodso Details on fire protection systemso The intended duration of operation, including connection and disconnection times and dateso Description of the temporary wiring, including connection methods, conductor type and size, and circuit overcurrent protection to be providedo Description how fire suppression system supply connections (water or another extinguishing agent)o Maintenance, service, and emergency response contact information.DeployedThere are restrictions on where mobile energy storage systems can be deployed. For example, they are not allowed to be deployed indoors, in covered parking garages, on rooftops, below grade, or under building overhangs. There is also a restriction on how long mobile energy storage systems can be deployed before they need to be treated as a permanent energy storage system installation, and that threshold is 30 days.Additional limitations for where a mobile energy storage system can be deployed include a 10 ft (3 m) limitation on how close it can be to various exposures and a 50 ft (15.3 m) limitation on how close it can be to specific structures with an occupant load of 30 or greater. See NFPA 855 or the image above for more details on the exposures and occupancies.An energy storage system contains a large amount of energy stored in a small space, which may make it the target for those who look to cause harm. For this reason, a deployed mobile energy storage system is required to be provided with a fence with a locked gate that keeps the public at least 5 ft (1.5 m) away from the ESS.ConclusionThere are many applications where mobile energy storage systems can play a pivotal role in helping deliver electricity to where it is needed. While this technology has great practical applications and even more potential, it’s important to recognize that it also brings unique hazards. Adherence to the requirements of NFPA 855 can help keep our communities safe while embracing current technology.Here are some additional NFPA® resources related to ESS safety:-       Energy storage system landing page-       Energy Storage and Solar Systems Safety Online Training-       Energy Storage Systems Safety Fact Sheet

As Egg Prices Continue to Soar, Ensure DIY Chicken Coop Projects Are Done Safely

If chickens don’t fly, then how can egg prices continue to soar? Poor attempts at dad jokes aside, record-high egg prices are something we are all facing at the moment and, frankly, don’t find all that funny.According to data from the US Bureau of Labor Statistics, the average price of eggs more than doubled between January 2022 and December 2022, from $1.93 per dozen to $4.25 per dozen. Since January 2021, when egg prices were on average $1.47 per dozen, the price has nearly tripled. While many individuals had previously chosen to raise chickens at their residence for access to fresh eggs, elevated egg prices now have many contemplating doing the same to save money. RELATED STORY  After a large chicken farm fire in Connecticut, some people are questioning whether something suspicious is going on. The truth is there’s nothing unusual about fires at livestock storage and production facilities. Read more. One of the most critical components in raising chickens is having a structure to provide nesting areas for egg laying and safe shelter from predators such hawks, coyotes, and foxes. Creating structures, such as chicken coops, can often become do-it-yourself (DIY) projects for homeowners.Communication between the local jurisdiction and homeowners about the safe building, and upkeep, of residential DIY chicken coops is key. Below you will find some information on some potential dangers and guidelines to help mitigate the associated risk, as well as a simple tip sheet to that can be shared with others in your community. The danger of DIY While it is always recommended that people reach out to the local building department to determine whether or not a chicken coop would need any permits or inspections, the reality is that in many cases these structures are not inspected. In some areas, jurisdictions have excluded permitting and inspections for structures used in private agricultural applications like chicken coops. In other cases, the homeowner may simply not be aware of the potential risks they are exposing themselves to by doing the work themselves and not having adequate inspections performed. Bad information can also increase risk. An internet search for “raising chickens” led me to a popular DIY site that many homeowners are familiar with. In reviewing the step-by-step process that was provided for raising chickens, it did not take very long before I became astounded at some of the recommendations. As part of the step for setting up a brooder, which is a heated nesting place for chicks, it was recommended to get a cardboard or plastic box, place it in your house, put pine shavings in the bottom of the box, and place a heat lamp on the side of the box. So, a homeowner is being advised to take a flammable box, add additional flammable material (pine shavings), attach a heat source to the flammable box, and place that box within their home. The immense risk associated with this advice may be caught easily by a cautious homeowner, but there are likely many individuals who would just follow the step-by-step instructions, putting themselves in unnecessary danger. "A homeowner is being advised to take a flammable box, add additional flammable material, attach a heat source to the flammable box, and place that box within their home.  Other risks and what the codes say From a codes and standards perspective, it is difficult to find requirements that are specific to residential chicken coops. Paragraph 17.1.3.3 of the 2022 edition of NFPA 150, Fire and Life Safety in Animal Housing Facilities Code, defines facilities where agricultural animals are housed in private, residential-type animal housing as Category 7 Class B. Yet when we look at 17.1.1.3, it states that Category 7 Class B facilities are exempt from the requirements of NFPA 150. Considering this information, we cannot look to NFPA 150 for requirements when building a residential chicken coop. When we begin to analyze the genuine danger that can be present within chicken coops, two of the most prevalent arise when dealing with sources of electricity and heat. Let’s focus on electricity for the moment. To start, electrical work should always be performed by a qualified electrician who is versed in the requirements of NFPA 70®, National Electrical Code® (NEC®). Electrical receptacle needs for the chicken coops should be well thought out to avoid the need to use extension cords. Because of the outdoor location and moisture associated with that environment, which can even become an issue inside of the chicken coop, all receptacles should be provided with ground-fault circuit interrupter (GFCI) protection.Poultry dust buildup is a concern for the electrical system as well. To help avoid contact with ignition sources such as the internal components of receptacles and switches, dust-resistant boxes and covers should be utilized as well as implementing light fixtures with fully enclosed lamps. Any dust buildup on electrical components should be cleaned regularly. All electrical equipment that is used in chicken coops, such as heat lamps and electrically heated poultry waterers, should be listed by a qualified testing laboratory. For safety reasons, listed electrical equipment should only be used based on its listing instructions, and non-listed and makeshift equipment should be avoided.Heated waterers, heat lamps, and space heaters might be utilized in chicken coops to keep water from freezing during the winter months, as well as within brooders to keep chicks warm. Because chicks cannot regulate their body temperature for the first few weeks of life, supplemental heat is necessary. Temperatures as high as 95 degrees Fahrenheit are needed during their first week of life, then the temperature gradually descends to about 65 degrees over the next several weeks until chicks can regulate their own body temperature. Hay, bedding, and other combustible materials close to heat sources can become a significant fire hazard within chicken coops and brooders. NFPA® offers a helpful “Backyard Chicken Coop Safety” tip sheet for the general public that touches on many of these topics and more. Please feel free to share with your community through social media and outreach events. Chicken coop fires are very real, as evidenced by a recent fire at Hillandale Farms in Bozrah, Connecticut, which killed over 100,000 chickens. While a backyard residential chicken coop may not be anywhere near the scale of this facility, the same potential for electrical and fire hazards still exists. Ensuring that all involved are aware those risks, and know how to mitigate them, is a critical component to maintaining the safety of people, the flock, the chicken coop, and any surrounding buildings on the property. Don’t put any, let alone all, of the eggs in an unsafe basket.

Fire Alarm Pull Station Installation Height

Are you in the field installing a fire alarm system and need to know what the required fire alarm pull station height is? Or maybe you are working on a fire alarm design detail and want to know what the required height is for your fire alarm call point. You’re not the first one to ask this question, so I will get right into it.What is the required height for a fire alarm pull station?The simple answer that the operable part of the pull station needs to be at least 42 in. (1.07 m), and not more than 48 in. (1.22 m), above the finished floor. Additionally, one pull station needs to be within 5 ft (1.5 m) of each exit doorway on each floor where required to be installed in a building. Both of these requirements are shown below.The code requirementsNFPA 72®, National Fire Alarm and Signaling Code®, refers to a fire alarm pull station as a manually actuated alarm-initiating device, and defines it as a manually operated device used to initiate a fire alarm signal. Other publications may refer to a fire alarm pull station as a manual fire alarm station, pull station, fire box, call point, and so on. The requirements for the installation height can be found in Section 17.15 of the 2022 edition of NFPA 72. If you want to learn how you can easily find those requirements in the code using NFPA LiNK®, take a look at the video below.  It’s important to note that NFPA 72 does not require that manual initiating devices be installed in buildings. Instead, it provides the installation requirements when the devices are required by other codes such as NFPA 101®, Life Safety Code®, NFPA 1, Fire Code, or NFPA 5000®, Building Construction and Safety Code®.Mounting the back boxWhen mounting the back box for a manual pull station it is important to know the make and model of device that will ultimately be installed. As you saw above, the measurements are taken to the operable part of the device, not the middle of the device. Additionally, these measurements are taken from the finished floor, so when installing back boxes prior to the installation of the flooring, the thickness of the flooring must be accounted for in the measurement.TolerancesNFPA 72 allows a tolerance for the installation of devices. This tolerance is noted in 1.6.5 and A.1.6.5. Where dimensions are expressed in inches, it is intended that the precision of the measurement be 1 in., which would be plus or minus 1⁄2 in. The conversion and presentation of dimensions in millimeters would then have a precision of 25 mm, which would be plus or minus 13 mm. Therefore, the maximum height of the operable portion of the manually actuated alarm-initiating device could be up to 48.5 in. (1.233 m) if you account for the allowable tolerances in NFPA 72.Other wall-mounted appliance and device heightsDo you want to learn more about installation heights for other fire alarm devices, appliances, and equipment? The video referenced earlier in this blog outlines how you can use the direct navigation feature of NFPA LiNK (NFPA DiRECT®) to find the mounting heights not only for fire alarm pull stations, but also for other wall-mounted fire alarm equipment, as well as all of the supporting code requirements. 

Conspiracy Theory Brewing Over Chicken Farm Fires Is False, Experts Say

First it was fires in food processing facilities. Now, a seemingly growing number of people are claiming there’s something suspicious about fires occurring at chicken farms across the United States. “Good morning to everyone except the evil demons purposely screwing with the food supply,” an influential Twitter user who goes by the name Catturd tweeted on January 31. The tweet received more than 22,000 likes and more than 2,000 retweets. Good morning to everyone except the evil demons purposely screwing with the food supply.— Catturd ™ (@catturd2) January 31, 2023 In an attempt to provide proof that something nefarious is afoot, people like Catturd—who has 1.3 million followers on the popular social media website—have pointed to incidents like a fire that killed 100,000 chickens at a farm in Connecticut on January 28 and a fire in December that killed 250,000 chickens at a farm in Pennsylvania. The fires, these people allege, are most likely a government attempt at disrupting the food supply, leading to situations like the soaring egg prices that have gouged consumers’ wallets in recent months. Similar claims were made last spring, as many people, including Fox News host Tucker Carlson, purported that a string of fires that had occurred in food processing facilities was suspicious. That conspiracy theory was debunked by NFPA® and others. Experts say the high egg prices American consumers are seeing today are in reality a result of many factors, such as widespread avian flu and inflation. In other words, they have nothing to do with fires at chicken farms. Furthermore, experts say that, in general, these types of fires should not be seen as anything out of the ordinary. Fires at livestock and poultry production and storage properties are quite common and have been for years. NFPA also offers solutions to the problem. The numbers don’t lie According to data included in a recent Fire Protection Research Foundation (FPRF) report on fires in animal housing facilities, an estimated average of 930 fires occurred annually in livestock or poultry storage properties—which include spaces like barns, stockyards, and animal pens—in the US from 2014 to 2018. An additional average of 750 fires occurred annually in livestock production properties. Combined, that’s more than four fires on average each day. And these blazes can be exceptionally deadly for the animals housed there. The Animal Welfare Institute (AWI), an American nonprofit that supports animal rights, tracks barn fires in particular, and from 2013 to 2017, the AWI reports that more than 325 barn fires occurred in the US, killing nearly 2.8 million animals. Ninety-five percent of the animals killed were chickens. “When we see fires occurring at poultry storage facilities or at barns, we’re not really seeing anything out of the ordinary,” said Birgitte Messerschmidt, director of the NFPA Research division. “It’s just the opposite, actually. It’s simply the continuation of what we in the world of fire safety and fire statistics have been seeing play out for years.” “A lot of hazards can exist at livestock and poultry storage and production facilities, so it’s not unusual to see fires occur in these properties,” added Jacqueline Wilmot, a project manager with the FPRF, the research affiliate of NFPA. Risks & resources   According to the FPRF report, heating equipment is the number one cause of fires in animal housing facilities, with malfunctioning electrical systems coming in at a close second. The lack of smoke alarms and fire sprinklers as well as an abundance of fuel such as hay or straw at many of these locations all work to heighten the fire risk. One important resource that exists to help limit the number of these fires is NFPA 150, Fire and Life Safety in Animal Housing Facilities Code. Although NFPA 150 has existed in some form since 1979, it wasn’t until 2006 that the scope of the code was expanded beyond racehorse stables. (Read more about NFPA 150 and its origins in “Critter Life Safety Code,” the cover story of the November/December 2018 issue of NFPA Journal.) Even today, widespread awareness and use of NFPA 150 is lacking. The recent foundation report found that in a survey of 71 individuals who in some way represent the animal housing industry, roughly 60 percent of them had no familiarity with the code. According to NFPA’s CodeFinder® tool, only two states in the US reference NFPA 150, Delaware and Nevada. An opportunity exists “to create training outreach programs and other fire protection training to better educate animal housing facility owners and staff,” the report says. In addition to NFPA 150, NFPA also offers a number of barn fire safety tips aimed at consumers, which can be found for free online at nfpa.org/farms.Amid reports that people are rushing to buy their own chickens in the face of high egg prices, stay tuned for another NFPA blog next week that will provide safety tips for anyone looking to build a chicken coop in their backyard.

Basics of Fire Sprinkler Calculations: Selecting the Design Area in the Density/Area Method

Automatic fire sprinkler systems have consistently demonstrated their ability to reduce the impact of unwanted fires. But when a sprinkler system fails, many times it is due to insufficient water reaching the fire. An NFPA® research report titled “U.S. Experience with Sprinklers” found that when a system fails to contain a fire, 50 percent of the time it was because water did not reach the fire at all, and 31 percent of the time not enough water reached the fire. These statistics underscore the importance of effectively calculating the water demand needed for the automatic fire sprinkler system; otherwise, the system may not be effective at reducing the impact of a fire. This is the first in a series of blogs aimed at providing an overview of the basics of fire sprinkler design calculations (demand calculations) using the density/area design method found in the 2022 edition of NFPA 13, Standard for the Installation of Sprinkler Systems. Today we will focus on subsection 19.2.3, which addresses the water demand, and paragraph 28.2.4.2, which specifies the hydraulic calculation procedures specific to the density/area design method. Density/area method The density/area method can be generally defined as a given amount of water (sprinkler discharge rate) over a specified area. This given amount of water is known as the design density, which is intended to provide cooling and wet adjacent surfaces with the goal of controlling an unintended fire until it can be fully extinguished by emergency services. The area is the expected area of sprinkler operation, or remote area for which the given amount of water (design density) must be applied. For water demand calculations, it’s assumed all sprinklers in this area will operate. This area is often adjusted for things like quick-response sprinklers, sloped ceilings, dry-pipe, double interlock systems, and high-temperature sprinklers. Remote area When calculating the water demand needed for the system it is imperative that the correct location on the sprinkler system be chosen as the remote area. Although most fire sprinkler system calculations are done utilizing hydraulic calculation software, many are integrated into computer aided drafting (CAD) programs. The ability of the program to correctly calculate the water demand is directly related to the user’s ability to select the correct area. The area selected should be the hydraulically most demanding, which is often physically the furthest point from the sprinkler riser on the system. However, in some instances, pipe sizes may make an area physically closer to the riser more hydraulically demanding. An example of this may be an instance closer to the sprinkler riser, which utilizes a more condensed spacing than the physically most remote portion of the system. When in doubt, it is best to calculate multiple areas. Identifying the remote area The steps in identifying the remote area involve determining the area (square footage or square meters) from the design criteria, applying the necessary adjustments to this area, calculating the shape, determining the number of sprinklers necessary in the area, and selecting those sprinklers that meet the remoteness and shape criteria. Let’s walk through a basic example for remote area selection on a system with a main line and branch lines (not gridded or looped). The initial step is to determine the area (square footage or square meters) from Chapter 19. Since we’re utilizing the density/area method on a new system, Table 19.2.3.1.1 applies. Determining the occupancy hazard classification is very specific to the area being protected and is a bit out of scope for this blog but certainly a topic we will cover in this series. For the sake of our calculation, let’s assume we determined the occupancy to be an Ordinary Group I hazard.  You’ll notice we’re given two options for each hazard. This is because areas adjacent to combustible concealed spaces present a unique challenge—the fire may establish itself in the concealed space and a greater number of heads may activate. Let’s assume we’ve determined we are not adjacent to a combustible concealed space, so the 0.15 gpm/ft2 (6.1 mm/min/m2) over 1500 ft2 (140 m2) applies, thus our area is 1500 ft2 (140 m2). Remember, this area may be adjusted for things like quick-response sprinklers, sloped ceilings, dry-pipe, double-interlock systems, and high-temperature sprinklers. For our example, let’s assume none of these adjustments applies. After determining the size of the remote area, we’ll need to determine its shape. Paragraph 28.2.4.2.1 indicates that “a rectangular area having a dimension parallel to the branch lines at least 1.2 times the square root of the area of sprinkler operation (A)” is utilized. As an equation that is:  For the sprinkler operation area in this example, we get:  We’re going to assume we’re utilizing a sprinkler coverage area of 120 ft2 (11.1 m2), which is under the maximum allowable square footage for an Ordinary Group I hazard with standard-spray sprinklers of 130 ft2 (12 m2) with sprinklers spaced 12 ft (3.6 m) apart along the branch line and branch lines 10 ft (3 m) apart as shown below.  The next step is to determine the number of sprinklers in the area. To accomplish this, we’ll divide the area from Table 19.2.3.1.1 by the coverage area per sprinkler.  Since it’s not possible to activate half a sprinkler head, we round the number to 13 sprinklers. Now that we have the shape and the number of sprinklers in the design area, we apply that to our layout and select the 13 most remote sprinklers that meet our remote area shape criteria. To meet the shape requirement of 58 ft (14.2 m) long, we’d need to utilize six sprinklers along the branch line. To meet the number of sprinklers, we’d need an additional seven sprinklers, six along the next branch line and one along the third. We’re permitted to utilize any sprinkler along the third branch line. Most commonly, the one closest to the cross main is selected as it will result in the greatest flow. This is shown graphically below.  As you can see, even in this simple example there are nuances to selecting the design. Keep in mind, this was one of many design options for new sprinkler systems in NFPA 13. Evaluation of existing systems has separate criteria. Make sure to utilize the correct option for your situation. Wrapping up Even when utilizing computer software, engineers and designers need to select these sprinklers correctly to ensure they accurately provide the water demand needed in the event of an unwanted fire. Next up in this series of blogs we’ll look at the K-factor formula for determining the flow of the starting sprinkler. For more information about NFPA 13 sprinkler system design, check out the NFPA 13 Online Training Series. The training has been updated recently to reflect the most current 2022 edition of NFPA 13. Module 2 of this training provides users with a comprehensive overview of the calculations we discussed in this blog. Watch a video about the training below.  

Basics of Fire Sprinkler Calculations: Selecting the Design Area and the Density/Area Method

Automatic fire sprinkler systems have consistently demonstrated their ability to reduce the impact of unwanted fires. But when a sprinkler system fails, many times it is due to insufficient water reaching the fire. An NFPA® research report titled “U.S. Experience with Sprinklers” found that when a system fails to contain a fire, 50 percent of the time it was because water did not reach the fire at all, and 31 percent of the time not enough water reached the fire. These statistics underscore the importance of effectively calculating the water demand needed for the automatic fire sprinkler system; otherwise, the system may not be effective at reducing the impact of a fire. This is the first in a series of blogs aimed at providing an overview of the basics of fire sprinkler design calculations (demand calculations) using the density/area design method found in the 2022 edition of NFPA 13, Standard for the Installation of Sprinkler Systems. Today we will focus on subsection 19.2.3, which addresses the water demand, and paragraph 28.2.4.2, which specifies the hydraulic calculation procedures specific to the density/area design method. Density/area method The density/area method can be generally defined as a given amount of water (sprinkler discharge rate) over a specified area. This given amount of water is known as the design density, which is intended to provide cooling and wet adjacent surfaces with the goal of controlling an unintended fire until it can be fully extinguished by emergency services. The area is the expected area of sprinkler operation, or remote area for which the given amount of water (design density) must be applied. For water demand calculations, it’s assumed all sprinklers in this area will operate. This area is often adjusted for things like quick-response sprinklers, sloped ceilings, dry-pipe, double interlock systems, and high-temperature sprinklers. Remote area When calculating the water demand needed for the system it is imperative that the correct location on the sprinkler system be chosen as the remote area. Although most fire sprinkler system calculations are done utilizing hydraulic calculation software, many are integrated into computer aided drafting (CAD) programs. The ability of the program to correctly calculate the water demand is directly related to the user’s ability to select the correct area. The area selected should be the hydraulically most demanding, which is often physically the furthest point from the sprinkler riser on the system. However, in some instances, pipe sizes may make an area physically closer to the riser more hydraulically demanding. An example of this may be an instance closer to the sprinkler riser, which utilizes a more condensed spacing than the physically most remote portion of the system. When in doubt, it is best to calculate multiple areas. Identifying the remote area The steps in identifying the remote area involve determining the area (square footage or square meters) from the design criteria, applying the necessary adjustments to this area, calculating the shape, determining the number of sprinklers necessary in the area, and selecting those sprinklers that meet the remoteness and shape criteria. Let’s walk through a basic example for remote area selection on a system with a main line and branch lines (not gridded or looped). The initial step is to determine the area (square footage or square meters) from Chapter 19. Since we’re utilizing the density/area method on a new system, Table 19.2.3.1.1 applies. Determining the occupancy hazard classification is very specific to the area being protected and is a bit out of scope for this blog but certainly a topic we will cover in this series. For the sake of our calculation, let’s assume we determined the occupancy to be an Ordinary Group I hazard.  You’ll notice we’re given two options for each hazard. This is because areas adjacent to combustible concealed spaces present a unique challenge—the fire may establish itself in the concealed space and a greater number of heads may activate. Let’s assume we’ve determined we are not adjacent to a combustible concealed space, so the 0.15 gpm/ft2 (6.1 mm/min/m2) over 1500 ft2 (140 m2) applies, thus our area is 1500 ft2 (140 m2). Remember, this area may be adjusted for things like quick-response sprinklers, sloped ceilings, dry-pipe, double-interlock systems, and high-temperature sprinklers. For our example, let’s assume none of these adjustments applies. After determining the size of the remote area, we’ll need to determine its shape. Paragraph 28.2.4.2.1 indicates that “a rectangular area having a dimension parallel to the branch lines at least 1.2 times the square root of the area of sprinkler operation (A)” is utilized. As an equation that is:  For the sprinkler operation area in this example, we get:  We’re going to assume we’re utilizing a sprinkler coverage area of 120 ft2 (11.1 m2), which is under the maximum allowable square footage for an Ordinary Group I hazard with standard-spray sprinklers of 130 ft2 (12 m2) with sprinklers spaced 12 ft (3.6 m) apart along the branch line and branch lines 10 ft (3 m) apart as shown below.  The next step is to determine the number of sprinklers in the area. To accomplish this, we’ll divide the area from Table 19.2.3.1.1 by the coverage area per sprinkler.  Since it’s not possible to activate half a sprinkler head, we round the number to 13 sprinklers. Now that we have the shape and the number of sprinklers in the design area, we apply that to our layout and select the 13 most remote sprinklers that meet our remote area shape criteria. To meet the shape requirement of 58 ft (14.2 m) long, we’d need to utilize six sprinklers along the branch line. To meet the number of sprinklers, we’d need an additional seven sprinklers, six along the next branch line and one along the third. We’re permitted to utilize any sprinkler along the third branch line. Most commonly, the one closest to the cross main is selected as it will result in the greatest flow. This is shown graphically below.  As you can see, even in this simple example there are nuances to selecting the design. Keep in mind, this was one of many design options for new sprinkler systems in NFPA 13. Evaluation of existing systems has separate criteria. Make sure to utilize the correct option for your situation. Wrapping up Even when utilizing computer software, engineers and designers need to select these sprinklers correctly to ensure they accurately provide the water demand needed in the event of an unwanted fire. Next up in this series of blogs we’ll look at the K-factor formula for determining the flow of the starting sprinkler. For more information about NFPA 13 sprinkler system design, check out the NFPA 13 Online Training Series. The training has been updated recently to reflect the most current 2022 edition of NFPA 13. Module 2 of this training provides users with a comprehensive overview of the calculations we discussed in this blog. Watch a video about the training below.  

Basics of Fire Sprinkler Calculations: Selecting the Design Area in the Density/Area Method

Automatic fire sprinkler systems have consistently demonstrated their ability to reduce the impact of unwanted fires. But when a sprinkler system fails, many times it is due to insufficient water reaching the fire. An NFPA® research report titled “U.S. Experience with Sprinklers” found that when a system fails to contain a fire, 50 percent of the time it was because water did not reach the fire at all, and 31 percent of the time not enough water reached the fire. These statistics underscore the importance of effectively calculating the water demand needed for the automatic fire sprinkler system; otherwise, the system may not be effective at reducing the impact of a fire. This is the first in a series of blogs aimed at providing an overview of the basics of fire sprinkler design calculations (demand calculations) using the density/area design method found in the 2022 edition of NFPA 13, Standard for the Installation of Sprinkler Systems. Today we will focus on subsection 19.2.3, which addresses the water demand, and paragraph 28.2.4.2, which specifies the hydraulic calculation procedures specific to the density/area design method. Density/area method The density/area method can be generally defined as a given amount of water (sprinkler discharge rate) over a specified area. This given amount of water is known as the design density, which is intended to provide cooling and wet adjacent surfaces with the goal of controlling an unintended fire until it can be fully extinguished by emergency services. The area is the expected area of sprinkler operation, or remote area for which the given amount of water (design density) must be applied. For water demand calculations, it’s assumed all sprinklers in this area will operate. This area is often adjusted for things like quick-response sprinklers, sloped ceilings, dry-pipe, double interlock systems, and high-temperature sprinklers. Remote area When calculating the water demand needed for the system it is imperative that the correct location on the sprinkler system be chosen as the remote area. Although most fire sprinkler system calculations are done utilizing hydraulic calculation software, many are integrated into computer aided drafting (CAD) programs. The ability of the program to correctly calculate the water demand is directly related to the user’s ability to select the correct area. The area selected should be the hydraulically most demanding, which is often physically the furthest point from the sprinkler riser on the system. However, in some instances, pipe sizes may make an area physically closer to the riser more hydraulically demanding. An example of this may be an instance closer to the sprinkler riser, which utilizes a more condensed spacing than the physically most remote portion of the system. When in doubt, it is best to calculate multiple areas. Identifying the remote area The steps in identifying the remote area involve determining the area (square footage or square meters) from the design criteria, applying the necessary adjustments to this area, calculating the shape, determining the number of sprinklers necessary in the area, and selecting those sprinklers that meet the remoteness and shape criteria. Let’s walk through a basic example for remote area selection on a system with a main line and branch lines (not gridded or looped). The initial step is to determine the area (square footage or square meters) from Chapter 19. Since we’re utilizing the density/area method on a new system, Table 19.2.3.1.1 applies. Determining the occupancy hazard classification is very specific to the area being protected and is a bit out of scope for this blog but certainly a topic we will cover in this series. For the sake of our calculation, let’s assume we determined the occupancy to be an Ordinary Group I hazard.  You’ll notice we’re given two options for each hazard. This is because areas adjacent to combustible concealed spaces present a unique challenge—the fire may establish itself in the concealed space and a greater number of heads may activate. Let’s assume we’ve determined we are not adjacent to a combustible concealed space, so the 0.15 gpm/ft2 (6.1 mm/min/m2) over 1500 ft2 (140 m2) applies, thus our area is 1500 ft2 (140 m2). Remember, this area may be adjusted for things like quick-response sprinklers, sloped ceilings, dry-pipe, double-interlock systems, and high-temperature sprinklers. For our example, let’s assume none of these adjustments applies. After determining the size of the remote area, we’ll need to determine its shape. Paragraph 28.2.4.2.1 indicates that “a rectangular area having a dimension parallel to the branch lines at least 1.2 times the square root of the area of sprinkler operation (A)” is utilized. As an equation that is: L = 1.2√AWhere: L = the dimension parallel to the branch line (ft or m)A = the area of operation (ft2 or m2) For the sprinkler operation area in this example, we get: L = 1.2√(1500 ft2  (L = 1.2√140 m2)L = 46.5 ft (L = 14.2 m) We’re going to assume we’re utilizing a sprinkler coverage area of 120 ft2 (11.1 m2), which is under the maximum allowable square footage for an Ordinary Group I hazard with standard-spray sprinklers of 130 ft2 (12 m2) with sprinklers spaced 12 ft (3.6 m) apart along the branch line and branch lines 10 ft (3 m) apart as shown below.  The next step is to determine the number of sprinklers in the area. To accomplish this, we’ll divide the area from Table 19.2.3.1.1 by the coverage area per sprinkler. 1500 ft2 / 120 ft2 = 12.5 sprinklers Since it’s not possible to activate half a sprinkler head, we round the number to 13 sprinklers. Now that we have the shape and the number of sprinklers in the design area, we apply that to our layout and select the 13 most remote sprinklers that meet our remote area shape criteria. To meet the shape requirement of 46.5 ft (14.2 m) long, we’d need to utilize five sprinklers along the branch line. To meet the number of sprinklers, we’d need an additional eight sprinklers, five along the next branch line and three along the third. We’re permitted to utilize any of the sprinklers along the third branch line. Most commonly, the ones closest to the cross main are selected as they will result in the greatest flow. This is shown graphically below.  As you can see, even in this simple example there are nuances to selecting the design. Keep in mind, this was one of many design options for new sprinkler systems in NFPA 13. Evaluation of existing systems has separate criteria. Make sure to utilize the correct option for your situation. Wrapping up Even when utilizing computer software, engineers and designers need to select these sprinklers correctly to ensure they accurately provide the water demand needed in the event of an unwanted fire. Next up in this series of blogs we’ll look at the K-factor formula for determining the flow of the starting sprinkler. For more information about NFPA 13 sprinkler system design, check out the NFPA 13 Online Training Series. The training has been updated recently to reflect the most current 2022 edition of NFPA 13. Module 2 of this training provides users with a comprehensive overview of the calculations we discussed in this blog. Watch a video about the training below.  

Electrical Room Basics, Part 3

This is the last in a three-part series on electrical rooms. Read Part 1 here and Part 2 here. Working space about electrical equipment is covered in Article 110 of the NEC. Up to this point, we have discussed electrical rooms and how the National Electrical Code® (NEC®)—specifically, 110.26—helps ensure there is enough space, especially working space, in those rooms or areas. In Part 2, we observed that changing the voltage alters some of the clearance requirements for the equipment in electrical rooms (see 110.32 and 110.34 of the NEC).Now, we will look at an electrical enclosure, vault, or tunnel that is being used as a method for guarding electrical equipment and see how it affects clearances for working space about electrical equipment.What is an electrical enclosure? First, let’s look in Article 100 to see if there is a definition for a vault or tunnel. We find there isn’t one, but we do find a definition for enclosure. Enclosure is defined as “the case, housing of an apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts, or to protect the equipment from physical damage.”So, does this definition cover an electrical room or vault? I think it could, because the vaults are areas typically surrounded by walls and frequently some form of lockable entrance.Does a vault or enclosure still require working space for electrical equipment? Yes, Parts II and III of Article 110 cover these requirements. For voltages of 50 to 1000 volts, nominal, 110.27(A)(1) would address the use of a room, vault, or similar enclosure that is accessible only to qualified persons, as a means of protection against accidental contact with live parts. For the over 1000 volts, nominal, installations, 110.31(A)—which deals with electrical vaults, including their construction requirements—would apply.Often, we see vaults being utilized as electrical rooms for installations over 1000 volts versus the under-1000-volt installations. This is in part due to electrical installations using exposed terminations or the use of larger substations and switches, which could increase the risk of accidental contact with live parts, depending on the type of equipment.Construction of enclosures Construction of the vault roof and walls must not be made from studs or wall board, but instead from construction materials that will provide adequate structural strength for the conditions and possess at minimum a 3-hour fire rating. This is usually accomplished using materials that are made from or contain concrete, like a masonry block wall with pre-cast concrete planks for the roof and floor, or a complete pre-cast concrete unit. Where the floor is in contact with earth it must not be less than 4-inch-thick concrete. However, where vacant space or stories are below the floor, it may need to be engineered to be able to structurally withstand the loads imposed on the floor.A vault will normally have access doors as well, which are required to be tight-fitting and have a 3-hour fire rating, unless the vault has an approved fire suppression system installed, in which case the doors can be 1-hour fire rated. These doors must also be lockable, to restrict access to unqualified persons. To allow safe egress in the event of an electrical injury, the doors must be equipped with panic hardware and open 90 degrees in the direction of egress. Don’t forget the signage that must be on the doors (See Part 2 in this blog series for more on signage). Should an electrical catastrophic failure occur, the vault’s robust construction will help mitigate damage to other portions of the building, which could ultimately save lives.This type of heavy-duty construction requires detailed planning from the electrical contractor and design professional for all electrical equipment locations and the penetrations into the vault from feeders, branch circuits, or raceways that will be connecting to that electrical equipment. These penetrations must not reduce the rating of the vault.The electrical equipment contained in the vault, such as the switchgear, transformers/substations, and motor control centers (MCC), must meet the working space requirements found in 110.26, 110.32, and 110.34 of the NEC. The applicable NEC section is determined by the highest nominal voltage for the equipment in a particular area, since there may be more than one voltage within a vault. Where high-voltage equipment is contained within the same vault as equipment 1000 volts or less, there may need to be some separation in accordance with 110.34(B). If the separation is accomplished with a fence controlled by locks, then 110.31 would apply. Table 110.31 contains distance values for the required space between the equipment and the separating fence. Note that the fence cannot be within the working space measurements found in Table 110.34(A).Adding electrical equipment in a vault does not reduce the working space requirements found in 110.26 or 110.34. It just adds some additional items to work around. Whether your electrical equipment is in an electrical room or a vault, you must maintain proper clearances for worker safety.A great way to learn more about working space about electrical equipment is to register for the NFPA online training series on the 2023 edition of the NEC. Working space about electrical equipment is covered in the General Equipment Installation Practices section of this training. Learn more about this comprehensive, self-paced training.