Topic: Electrical

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 storage When 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-transit While 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 documents Before 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 Checklist o Information for the mobile energy storage system equipment and protection measures in the construction documents o 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 exposures o Location and content of signage o Description of fencing to be provided around the energy storage system and locking methods o Details on fire protection systems o The intended duration of operation, including connection and disconnection times and dates o Description of the temporary wiring, including connection methods, conductor type and size, and circuit overcurrent protection to be provided o Description how fire suppression system supply connections (water or another extinguishing agent) o Maintenance, service, and emergency response contact information. Deployed There 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. Conclusion There 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 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, 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 of 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.

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.  

Changes to Kitchen Island and Peninsula Receptacle Outlet Requirements for the Past Three NEC Editions

Requirements for kitchen island and peninsula receptacle outlets have been a part of the National Electrical Code® (NEC®) since the 1990 edition. At that time, 210.52(c) stated: “Island and peninsula counter tops 12 inches (305 millimeters) or wider shall have at least one receptacle for each four feet (1.22 meters) of counter top.” Over the course of the next 30-plus years, there were many significant changes made around island and peninsula receptacle outlet requirements within the NEC. Perhaps no changes to these requirements represented a larger swing of the pendulum than those we have seen over the past three cycles: the 2017, 2020, and 2023 NEC.   2017 NEC Requirements   The following are the relevant sections and requirements for island and peninsula receptacle outlets based on the 2017 NEC. They have been paraphrased in this blog. ·       210.52(C)(2) and 210.52(C)(3) require at least one receptacle to be installed at each island or peninsula having a countertop with a long dimension of 24 inches (600 millimeters) or greater and a short dimension of 12 inches (300 millimeters) or greater. o   The peninsula countertop dimension is measured from the connected perpendicular wall. ·       210.52(C), Exception to (5) allows for receptacle outlets to be mounted a maximum of 12 inches (300 millimeters) below island and peninsula countertops and work surfaces as long as they are not located where the countertop or work surface extends more than 6 inches (150 millimeters) beyond its support base, in either of these two scenarios: o   Where the construction is for the physically impaired. o   On island or peninsula countertops or work surfaces where the surface is entirely flat (e.g., no backsplash) and has no means to mount a receptacle within 20 inches above the countertop or work surface, such as on an overhead cabinet. One of the significant changes between the 2014 and 2017 NEC requirements was in 210.52(C)(3) addressing peninsular countertop spaces. In the 2014 NEC, the peninsular countertop was required to be measured from the “connecting edge,” which was then changed to measuring from the “connected perpendicular wall” in the 2017 NEC. In the 2017 NEC, 210.52(C), Exception to (5) was revised to also include “work surfaces” as being a part of the requirement, along with countertops. This is consistent with changes in other areas within 210.52 of the 2017 NEC that added the term work surfaces, including changing the title of 210.52(C) to “Countertops and Work Surfaces.”   2020 NEC Requirements   In the 2020 NEC, island and peninsula receptacle outlet requirements saw a major overhaul from those in the 2017 NEC. Where the 2017 NEC required at least one receptacle outlet to be installed in islands and peninsulas with a long dimension of 24 inches or greater and a short dimension of 12 inches or greater, there was never a scenario that required more than one receptacle outlet to be installed in these locations. Changes to the 2020 NEC required at least one receptacle outlet to be installed in all islands and peninsulas, and potentially more depending on the overall square footage of the countertop or work surface for the island or peninsula. Here is an overview of the changes to 210.52(C) in the 2020 NEC (paraphrased): ·      210.52(C)(2) has been revised to cover both islands and peninsulas and has added the following requirements: o   At least one receptacle outlet must be installed within an island or peninsula for the first 9 square feet (0.84 square meters), or fraction thereof, of the countertop or work surface. o   An additional receptacle outlet must be installed within an island or peninsula for each additional 18 square feet (1.7 square meters), or fraction thereof, of the countertop or work surface. o   At least one receptacle outlet must be installed within 2 feet (600 millimeters) of the outer end of a peninsula countertop or work surface. o   Additional required receptacle outlets are permitted to be located as determined by the installer, designer, or building owner. o   A peninsula countertop must be measured from the connected perpendicular wall. o   The location of the receptacle outlets must be in accordance with 210.52(C)(3). The picture below depicts a 3-foot by 8-foot island. Based on changes to the 2020 NEC, the first 9 square feet (represented by the light blue area) require a receptacle outlet to be installed. That leaves a 3-foot by 5-foot area remaining in the yellow area. That area totals 15 square feet, therefore falling into a fraction of an additional 18 square feet and requiring an additional receptacle on the island, for a total of two. The locations that these two receptacles are installed must be done in accordance with 210.52(C)(3).   For the 2020 NEC, 210.52(C)(3) was revised to cover receptacle outlet locations, which were previously covered in the 2017 NEC by 210.52(C)(5). Revised 210.52(C)(3) provides three different list items identifying where island and peninsula receptacles are permitted to be located (paraphrased): 1.     On or above countertop or work surfaces, but no more than 20 inches above. 2.     In the countertop or work surface using a receptacle outlet assembly that is listed for the application. 3.     Where installed not more than 12 inches below the countertop or work surface and not located where the countertop or work surface extends more than 6 inches beyond its support base. Receptacle outlets that are not readily accessible or are located in assigned spaces for appliances within the peninsula or island (e.g., dishwasher, mini fridge, etc.) are not permitted to count as the required receptacles outlets for the island or peninsula.   2023 NEC Requirements   Section 210.52(C)(2) saw extensive revisions between the 2020 and 2023 NEC. All of the requirements around receptacle outlets being installed based on the square footage of the countertop and work surface of islands and peninsulas were removed. Perhaps more significant, the requirement for any receptacle to be installed within islands and peninsulas was removed. You read that right: No receptacle outlet is required to be installed within islands or peninsulas based on the 2023 NEC—with a caveat. The revisions to 210.52(C)(2) in the 2023 NEC essentially changed island and peninsula receptacles to have two requirements (paraphrased): 1.     Receptacle outlets in islands and peninsulas, if installed, must be done in accordance with 210.52(C)(3). 2.     If a receptacle outlet is not provided for islands and peninsulas, provisions must be provided for the addition of a receptacle outlet in the future. Note: The means by which the provision is made for a future receptacle outlet is not stated by the NEC; therefore, the authority having jurisdiction (AHJ) will need to be consulted to determine what they will consider as meeting this requirement.   Watch a related video from the NFPA LiNK® YouTube channel Section 210.52(C)(3) has also been revised for the 2023 NEC, essentially to provide the following three options for where island and peninsula receptacle outlets can be installed (paraphrased): 1.     On or above countertop or work surfaces, but no more than 20 inches above. 2.     In a countertop using a receptacle outlet assembly listed for use in countertops. 3.     In a work surface using a receptacle outlet assembly listed for use in work surfaces or listed for use in countertops. What can be noted as a major change in the 2023 NEC from the receptacle outlet location options for islands and peninsulas in 210.52(C)(3) of the 2020 NEC, is the ability to install receptacle outlets below countertops and work surfaces. Receptacle outlets for islands and peninsulas are no longer able to be installed below the countertop and work surface level. As part of its substantiation for the change, NEC Code Making Panel 2 cited Consumer Product Safety Commission (CPSC) data showing that between 1991 and 2020, an estimated 9,700 people, many of them children, were treated in United States emergency departments for burns and other injuries after pulling on or running into power cords plugged into receptacle outlets installed below island and peninsula work surfaces.  Those who opposed the change, however, cited accessibility concerns. Because of this change, as well as other changes to 210.52(C)(2) and (C)(3), the 2023 NEC essentially provides three options for island and peninsula receptacle outlet installations, or non-installations, as depicted in the bullet points and photo below: ·      Option 1 permits the installation of receptacle outlets above the countertop or work surface, but not more than 20 inches above. Islands and peninsulas with elevated backsplashes present an opportunity for using this option. ·      Option 2 permits installation of receptacle outlets within the countertop or work surface, provided a receptacle outlet assembly listed for the application is utilized. ·      Option 3 is utilized when no receptacle outlet is installed within the island or peninsula. In that case, the 2023 NEC requires a future provision to be made where a receptacle outlet could be installed at a later date. The junction box with protective flexible conduit for the NM-B cable is just one example of how this could possibly be done, but it is not required to be done this way per the 2023 NEC.     Change and the NEC are practically synonymous. But it is rare that we see such drastic changes in requirements within the same section of the NEC over such close cycles. Personally, I believe that these changes show how important it is for the public to get involved in the NFPA® standards development process. Whether you’re an individual with relevant data that you can provide or an electrician that has an idea of what should change, the safety that the NEC provides depends on your input. I encourage everyone to learn more about the standards development process to get involved.

A Better Understanding of NFPA 70E: Setting Up an Electrical Safety Program (Part 10 – Incident Investigations)

Does an employee get punished when they make a mistake? Are they afraid of notifying a supervisor when something goes wrong? Is an employee who points out a safety issue sent back to work without having the issue resolved? One NFPA 70E®, Standard for Electrical Safety in the Workplace® requirement that is occasionally not well addressed in an electrical safety program (ESP) is the incident investigation requirement in Section 110.5(J). The reason is that with electricity no incident should be treated as minor. Every 120-volt electric shock is a brush with death. However, electric shocks, minor burns, and unjustified live work are not reported until a greater injury occurs. Investigations required by NFPA 70E are not for the purpose of assigning blame. They are to improve employee safety. An ESP must include the details of how, why, when and what happens with incident investigations. Incident investigations should not be limited to those where an employee is injured to the point where medical attention is required. An electric current’s path through a human body affects each person differently. An employee with a pacemaker may have a problem days after an incident. Employees should be trained and encouraged to report any dangerous situation as well as any injury regardless of the cause or severity. The investigation could reveal that the ESP, work procedures, protective equipment, training, or test instruments require revision to prevent a future occurrence, injury, or death. Without an investigation into what occurred there is possibility that a fatality could happen the next time that same task is conducted. The employee could have received an electric shock due to unjustified energized work, insufficient training, damaged equipment, wrong qualification for the task, inappropriate personal protective equipment, flawed job planning, or errors in the procedure. But none of that will matter unless this near-death situation is reported and the cause rectified. Employers and employees must accept their responsibilities and work together to find the cause of any incident. Although electrical incidents are often the result of human error, an employee does not intentionally initiate an electrical incident. However, it is important that an enforcement program be established for willful violations of safety regulations. The ESP must assign responsibility for each step in the incident investigation. The procedure must not only cover what is required as part of an investigation but the training for the investigator. The incident and investigation must be documented. There can be no improvement in safety without a final step requiring that necessary changes be incorporated. If it is determined that training was the culprit, modification of the training program could include increasing the frequency of training or adding follow-up verification of compliance. The ESP must address who is be responsible for incorporating the improvements. Do not use incident investigations as means to punish but to gain knowledge and to educate. Involving employees in the process gives them a personal stake in improving workplace safety. For the ESP to work, employers and employees must cooperate and trust that safely returning home each day is paramount in the workplace. 

Electrical Room Basics, Part 2

This is the second in a series of blogs on electrical rooms. Read Part 1 here. In my previous blog, we discussed the misconception that electrical rooms are covered in 110.26 of NFPA 70®, National Electrical Code® (NEC®), when they are actually covered as an option for guarding against accidental contact with live parts in 110.27. Now, we will explore the electrical room and working space for equipment over 1,000 volts, nominal. Does 110.26 still apply to that working space within the electrical room? The answer would be no, because 110.26 is in Part II of Article 110, which covers installations under 1,000 volts, nominal. The applicable part of 110 is Part III: Over 1,000 Volts, Nominal. Specifically, 110.32, Work Space about Equipment; 110.33, Entrance to Enclosures and Access to Working Space; and 110.34, Work Space and Guarding. Coincidently, these sections have some similarities to 110.26, such as requiring: ·       Height for working space of 6.5 feet, measured from floor or platform ·       Working space not to be used for storage ·       90-degree opening of equipment doors or hinged panels ·       Equipment doors not to impede entrance to and egress from the working space ·       Grade, floor, or platform to be as level as practical for the entirety of the working space ·       24-inch wide by 6.5-foot high entrance to and egress from the working space As you can see, the NEC correlates sections with one another when it makes sense. There are, however, a few differences among these sections, one of which is the width of the working space. Section 110.26(A)(2) allows a minimum width of 30 inches for working space, while 110.32 allows a minimum width of 36 inches for that same space. Another difference is the depth of the working space. Table 110.26(A) has varying depths from 3 to 5 feet, while Table 110.34(A) has depths ranging from 3 to 12 feet. All these distances are dependent on the specific condition and nominal voltage to ground. So, for example, for a high-voltage switchgear operating at 13,200 volts to ground, with grounded parts on the opposite side, the depth of working space would be 6 feet, measured from the front of the enclosure or exposed live parts. You will notice that higher voltages and higher hazard conditions require a greater depth of working space for worker safety. Section 110.27 covers the guarding of live parts under 1,000 volts, which in my previous blog could be considered a locked electrical room. For voltages over 1,000 volts, nominal, 110.31, Enclosures for Electrical Installations, would address the electrical room or enclosure for those installations. Some methods of enclosure could be: ·       An electrical vault ·       Electrical room or closet ·       A specific area surrounded by a wall, screen, or fence These methods are designed and constructed according to the nature and degree of hazard associated with the installation. Additional protective measures are required for installations involving walls, screens, or fences that are used to deter access by unqualified persons. These measures may include additional height or barbed wire. These requirements are different from those found in 110.26 and 110.27. Typically, the electrical room or vault access doors are locked to prevent access by unqualified persons, or those doors must be under continuous observation. The doors to these areas are required to open in the direction of egress and be equipped with panic hardware or listed fire exit hardware that opens upon simple pressure. For installations over 1,000 volts, nominal, these locked or monitored rooms, enclosures, or vaults must have a warning sign on the door reading, “DANGER – HIGH VOLTAGE – KEEP OUT.” This sign must also comply with the provisions outlined in 110.21(B) around their durability to withstand exposure to the environment and specific marking requirements. Section 110.27(C) also requires a warning sign for installations of 1,000 volts or less, where there are exposed live parts. It must be placed on the door but is only required to be marked to forbid unqualified persons to enter the electrical room or other guarded area. The wording for the warning sign outside of spaces with over 1,000 volts is much stronger because of the potential exposure to high-voltage electrical hazards. Any exposed live parts adjacent to the electrical room, vault, or enclosure entrance must be suitably guarded. Other exposed parts may require additional means to prevent inadvertent contact with exposed live parts, such as screens, partitions, or fences within the electrical room. Any exposed live parts above the working space are required to be elevated at the distances found in Table 110.34(E) and have permanent ladders for access according to 110.33(B). These codes around working space and electrical rooms are for the protection of qualified persons who may be working on or in this equipment. Stay tuned to NFPA Today for Part 3 in this blog series titled Electrical Rooms, where we will explore electrical vaults. We will look at their construction and some of the requirements for electrical equipment being installed in them.  
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