Topic: Electrical

Determining Current Carrying Capacity of Conductors

The purpose of NFPA 70®, National Electrical Code® (NEC®) is the practical safeguarding of persons and property from the hazards that arise due to the use of electricity. Typically, this means protecting people from hazards like shock and arc flash, as well as property from fire. Fires resulting from improper wiring have historically been a significant threat ever since electrical systems have been installed within buildings. The NEC has established a long history of installation requirements to help prevent fires from occurring within the electrical system. One such requirement is to determine how much electrical current a conductor can carry continuously without exceeding the temperature rating of its insulation, or as the NEC refers to it, a conductor’s ampacity. However, determining ampacity requires the understanding of a number of other factors that come into play based on how a conductor is used and installed. This involves navigating charts, tables, and a number of other requirements to make sure that we calculate the correct ampacity. Depending on which conditions of installation and use exist, we find ourselves using a number of tables found throughout the NEC, but in particular, many of them are located in Article 310. There are a multitude of tables that spell out items such as conductor ampacity, temperature correction factors, and adjustment factors. So, let’s take a look at how these ampacity charts and tables can be used to ensure we select the appropriate conductor for the installation. There are a few questions we must ask ourselves before we begin. First, we need to know what the conductor insulation is rated for since ampacity is a function of the temperature rating of the insulation. Once we have established if we are using 60-, 75-, or 90-degree Celsius rated insulation, we can determine which column from the appropriate ampacity chart we need to be in. For conductors rated up to 2000V, ampacities can be found in Tables 310.16 through 310.21 based on how they are installed and other specific installation criteria. For the purpose of this blog, we will be using Table 310.16 for conductors installed in a raceway or cable with not more than 3 current carrying conductors total and in an ambient temperature of 30⁰C (86⁰F). These parameters are important to know since any deviation will necessitate a modification of the ampacity value in the tables. Once we know the insulation temperature rating, we can then find the corresponding ampacity in the appropriate column of Table 310.16 for the given conductor size (Note: certain types of insulation carry multiple ratings based on the location type, see Table 310.4 for conductor properties). After we have the ampacity value from Table 310.16, then we can apply adjustment and correction factors, if needed. Let’s start off with adjustment factors. First ask, are there more than three current carrying conductors in the raceway or cable, or are multiple cables installed without maintaining spacing for a distance greater than 24 inches? This count applies to total number of ungrounded (hot) conductors, even spares, and grounded (neutral) conductors on a 3 phase, 4-wire WYE system where: the circuit is single phase or, if the major part of the load consists of nonlinear loads [see 310.15(E)]. If the total current carrying conductor count exceeds three, then the ampacity from Table 310.16 must be adjusted in accordance with Table 310.15(C)(1) based on the total number of current carrying conductors. Next, we must look at the ambient temperature of where the conductor will be installed. If the ambient is anything other than what the starting ampacity is in Table 310.16, then we will find temperature correction factors in 310.15 based on deviations from the original chart’s ambient temperature. There are two temperature correction tables: Table 310.15(B)(1) for tables that are based on an ambient temperature of 30⁰C (86⁰F). Table 310.15(B)(2) for tables that are based on an ambient temperature of 40⁰C (104⁰F).     Because this blog is written based on Table 310.16, multipliers for temperature correction from Table 310.15(B)(1) should be used, since both charts are based on 30⁰C (86⁰F) ambient temperature. Table 310.15(B)(1) is also divided up by the temperature rating of the conductor insulation. Having already established this, simply find the corresponding multiplier based on the actual ambient temperature of the installation. Once all necessary adjustment and correction factors have been applied, there is still one more component that affects the ability of the conductors to safely carry electrical current continuously without exceeding the temperature rating of the insulation. This final factor is the termination of the conductor to any equipment. Termination points can be a limiting factor as these are common points on the electrical system for heat build up and rely on the conductor material to act as a heat sink to dissipate any build up of heat where the termination is made. For these requirements, we must consult section 110.14(C) for termination temperature limitations. These requirements help us determine the final current carrying capacity of our conductors so that they can safely handle the circuit current without damage to the insulation from excess heat. Section 110.14(C)(1) is split up into two scenarios. The first group is for circuits 100 amps or less or that are marked for the termination of conductor sizes 14 AWG through 1 AWG. The second group is for circuits with above 100 amps or terminations marked for larger than 1 AWG. The requirements for the first group limit the conductor use to conductors with a 60⁰C insulation rating or if conductors with a higher temperature rating are used, the final adjusted ampacity must not exceed that found in the 60⁰C column for the same size conductor, unless the terminations are also rated for a higher temperature in which case the final ampacity shall not exceed the value in the corresponding column. For the second group, above 100A or 1 AWG, the rules simplify a bit. The conductors must be rated for 75⁰C or higher and if the conductor is rated for higher than 75⁰C, the final ampacity must not exceed the corresponding ampacity in the 75⁰C column unless the terminations are identified as being rated for such higher temperatures. When we follow these requirements, the conductors that we install will be less likely to overheat and become a hazard, provided that the conditions of use remain the same. We’ve developed a free flow chart on this topic, including the tables mentioned above, to help you in your next installation. Be sure to download it here.   
Workers looking at plans

A Better Understanding of NFPA 70E: Job Safety Planning and Job Briefing

Before starting each job that involves exposure to electrical hazards, the employee in charge must complete a job safety plan and conduct a job briefing with the employees involved. That is the NFPA 70E®, Standard for Electrical Safety in the Workplace® requirement. It makes sense for the occasional need to justifiably expose an employee an electrical hazard but what about tasks that expose an employee to an electrical hazard daily? The short answer is yes; the requirement applies to those. The requirements apply just as written, the briefing and planning must be conducted before each job that exposes any employee to an electrical hazard.  What if it is a multistory printing press that has several problems every day? The answer is still yes. The primary method of protecting an employee from electrical hazards must be establishing an electrically safe work condition. Any exposure must be properly justified regardless of its nature. Documented procedures are necessary whether it is troubleshooting that exposes an employee to hazards or justified energized work that does. There is difference between troubleshooting and repair as I have pointed out many times. There are exclusions to requiring an energized work permit but that does not remove the need for a planning and briefing. How a facility’s electric safety program (ESP) is written plays a big part on how this is handled. A well written ESP should not allow any employee to decide on their own when or why they will be exposed to an electrical hazard. The ESP should not allow an employee to make up a work procedure on the fly or guess at the hazards or protective equipment (PPE) necessary to perform the task even if the task is perceived as routine. If an employee is exposed daily to an electrical hazard because of the same issue it would be better to fix the problem rather than expose them to the hazard daily. Maybe the problem cannot be fixed because of the nature of the equipment’s use, but it might be possible to use the hierarchy of risk controls to reduce the hazard or risk while performing that daily task. Either way, each day you will find a way to justify exposing the employee to the hazard. A safety procedure and energized work permit could be written for that specific repetitive task. NFPA 70E does not prohibit such a permit but there are many safety issues that should be addressed before doing so. There may be no such thing as routine when it comes to electrical safety. For example, the need to enter an enclosure because of a thermal trip does not mean that the cause of the thermal trip is the same every time. A different hazard or risk could be lurking inside and, if the employee is not prepared for it, could lead to an injury.  An energized work permit may not be required if the task is limited to troubleshooting. However, the documented procedure, proper protective equipment, planning and briefing must still be used.  All of this is true whether it is a single recurring issue or tens of recurring issues. Section 110.5(I)(1) covers the minimum requirements for the planning stage and one requirement is that it be documented.  Any task must be planned in detail for there to be an effective job briefing. If the task is being conducted for the first time, work procedures must be developed before work begins. If the planning reveals shortcomings in the established ESP or work procedure, these must be addressed before the task is performed. The planning stage is when the specific hazards associated with the specific task are identified. It should be verified that necessary equipment will be available to perform the task. The job planning section does not address the energized work permit, but the permit could be used to gather the necessary information. Section 110.5(I)(2) addresses the job briefing. This is when the employee in charge goes over the plan and discusses the energized work permit with the employee assigned to the task. The job briefing needs to be performed before the work tasks are started. However, it should not be performed so far ahead that the employees involved might forget what was covered. The briefing should include a discussion of the work procedure so that all parties fully understand the procedure. The briefing also gives employees the opportunity to express any concerns they have about the task, the procedure, their qualifications, or their safety. The employee should affirm that they will not deviate from the plan or task scope. They should also acknowledge that any deviation from the specific assigned task must be discussed before being implemented and modified in the work plan or procedure. It should be confirmed that the appropriate and necessary equipment and current procedures have been given to the employee. NFPA 70E does not require that the briefing be documented since the documented plan and work permit cover the issues discussed. As the employee in charge, I would add briefing notes to the documented plan especially if there were issues raised during the briefing. I would also have the employee sign the plan or permit as acknowledgement that the briefing was conducted. The job briefing also serves a purpose to the employee in charge and the employer. The briefing is the time to verify that the energized work permit is properly authorized or that the task is limited to troubleshooting. The employee in charge is responsible for assuring the employee is qualified not only for the task on the specific equipment but they are the right employee for the assigned task. They should assess if the employee is impaired in some manner. They may have to apply for a new work permit before the task is started based on the briefing. They need to address any issues raised by the employee before permitting them to begin the task. They will be the point of contact if the assigned task evolves into something else. There nothing prohibiting the employee in charge from being the employee assigned the task. It might seem excessive for them to establish a plan and hold a briefing for themselves. Their self-briefing allows them to verify that everything for their safety has been considered. It also gives them time to question their own qualification for the task and equipment. They should not be up to their elbows in energized equipment then realize that the work procedure has not been updated for new equipment that had recently replaced the old equipment. This is all to protect an employee from becoming an injury or fatality. An employer should know who, when, why, and where an employee may need to be rescued after an incident. Every employee should know what is expected of them before they are put at risk of an injury. Any employee assigned energized work or exposed to electrical hazards is at risk of a potential injury even if they are wearing PPE. Skipping the required planning and job briefing may seem convenient until an employee is injured. An investigator might consider that nothing was done leading up to the injury without a record of a job safety planning and briefing regardless of the employer’s documented ESP. Did you know that the first program in the NFPA 125th Conference Series, “Empowering Electrical Design, Installation and Safety,” is now available on demand? Get additional insights about electrical safety in the workplace and NFPA 70E through a series of engaging presentations from industry experts. Topics include a look at electrical shock injuries and the effect on both the mind and body, electrical incident data and the importance of safety training, electric shock hazards and the relationship to new technology, and how OSHA uses 70E. A special roundtable discussion also features questions and answers about staying safe on the job. Register today and earn CEU credits for participating. The program is available on demand through May 18, 2022.
MENA group at conference

NFPA now offers Middle East and North Africa solutions page in Arabic

NFPA has launched a new Middle East and North Africa (MENA) solutions page in Arabic as part of its 125th Anniversary commitment to serving global stakeholders. The new microsite introduces building, electrical, fire, and life safety workers in MENA territories to the NFPA codes, standards, training and certification resources that are paramount for keeping pace with progress. Countries within the MENA region have experienced incredible growth over the last 25 years. The breakneck speed of development in the Gulf Region has led to electrical, fire protection, code enforcement, and inspection, testing, and maintenance (ITM) challenges like those experienced in the US and other countries over the last century – only in the Middle East and North Africa, safety issues are presenting in a more condensed, concerning manner. NFPA has spent decades working with government authorities and private entities in the Middle East to reduce risk, but this marks the first time the association has promoted relevant resources in Arabic for those charged with protecting people and property. NFPA is making its resources accessible to more than 400 million Arabic speaking people in Algeria, Bahrain, Comoros, Djibouti, Egypt, Iraq, Jordan, Kuwait, Lebanon, Libya, Mauritania, Morocco, Oman, Qatar, Saudi Arabia, Somalia, Tunisia, United Arab Emirates and Yemen. Anas Alzaid, the local NFPA representative in Saudi Arabia, assesses local safety concerns; builds relationships; develops safety strategies with existing and new alliances; and represents NFPA in regulatory, legislative, and technical circles.   Alzaid has identified the following NFPA guidance as priority solutions for cultivating an effective safety infrastructure throughout the burgeoning region:     NFPA 1 The Fire Code NFPA 13 The Standard for the Installation of Sprinkler Systems NFPA 20 Stationary Pumps for Fire Protection and NFPA 25 Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems  NFPA 30 Flammable and Combustible Liquids Code and NFPA 58 Liquefied Petroleum Gas Code NFPA 70® National Electrical Code® and NFPA 70E® Standard for Electrical Safety in the Workplace® NFPA 72 The National Fire Alarm and Signaling Code® NFPA 101® The Life Safety Code®   The new Arabic solutions page also provides information on a wide array of online and in-person training offerings, as well as classroom training programs that assist professionals looking to prepare for certification. Trainings are based on the job requirements and proficiencies found in NFPA codes, standards, and handbooks. “NFPA is synonymous with fire prevention and safety all over the world and has identified MENA as a priority region. Promoting NFPA codes, standards, and training solutions in Arabic so that stakeholders can understand the level of expertise it takes to establish a solid infrastructure, no matter the pace of development, is a great first step,” Alzaid said. “The new NFPA Arabic solutions page comes at a critical time in MENA’s history, and shows at-a-glance, the various steps it will take to connect the dots on safety in the Gulf Region.”
Structural reinforcing steel that serves as the pool shell bonding

Code Compliant Electrical Installation the Key to Swimmer Safety and a Secure Electrical System in Pools

Now that summer has arrived, many of us will be taking advantage of the nice weather to jump into swimming pools to cool off. But what many people don’t realize, is there’s a lot to keeping us safe from electrical hazards in these wet environments. Much of this depends on the initial electrical installation. Something that is often overlooked after the pool has been installed and inspected, is maintenance of the pool and associated pool equipment. As we all know, Father Time is not always kind to electrical installations, which may require re-inspections for safety. Based on changes to the 2020 National Electrical Code® (NEC®) the authority having jurisdiction (AHJ) is permitted to periodically inspect and test pools. If they so choose, municipalities can now implement a process to periodically inspect and test pools, associated pool equipment, and the equipotential bonding after the initial installation inspection to help ensure reliability and continued safety. A code compliant electrical installation for a pool, completed by a licensed qualified electrician, is vital to the overall performance of the electrical system and the swimmer’s ability to cool off safely. The conductive pool shell, perimeter surfaces, metal forming shell for underwater luminaires, ladder cups, diving board bracket, the water, and other metal surfaces are where the equipotential bonding system is found. This equipotential bonding system surrounds the pool with connections to a #8 AWG solid copper conductor. This solid copper conductor is terminated to all the above points then routed underground or within the concrete, back to the pool pump motor and terminated on the grounding lug located on pump motor. The NEC in Section 680.26(B)(6) requires sufficient length in the equipotential bonding conductor for future pump replacement. Best practice would be to provide enough additional conductor to terminate it anywhere on the motor in the event the lug is not in the same location. These connections are crucial to equalizing the electrical potential of all conductive surfaces, ladders, diving boards, underwater luminaries, and water that are all found with pools. Because pools are subject to corrosion and use corrosive chemicals, terminations, many of which are underground or within concrete, must be listed and labeled for the environment they are being installed in. People often think that once a pool is installed, all they need to do is add chemicals to the water and clean the pool. This myth is where problems arise as maintenance and periodic inspection and testing of the pool equipment is a very important part of the overall electrical safety of the pool. Ground Fault Circuit Interrupters (GFCIs) need to be tested in accordance with the manufacturer’s installation instructions, which is typically monthly. Also, as a part of the maintenance, grounding connections should be checked for corrosion, loose connections, or rust; all of these can inhibit the functioning of the equipotential bond, which could result in an electrical shock or an electric shock drowning (ESD). If corrosion is seen on any terminations, those points should be cleaned and or replaced by a qualified person as these connections are crucial to the safety of the people who use the pool. Pool pump motors do not last forever and therefore must be replaced, which requires the disconnection and reconnection of the equipotential bonding conductor from the motor. As previously mentioned, additional slack in the solid copper conductor is required at the motor location for motor replacement because consideration was taken for bonding lug location. When a state chooses to legislatively adopt the 2020 NEC, which makes it enforceable by an AHJ, Section 680.4 permits the periodic inspection and testing by the AHJ of the pool system. This may help encourage the maintenance and repair of the pool system and equipotential bond.   Maintenance on pools, associated pool equipment, and the equipotential bonding system is no different than maintaining a car by getting the oil changed. It is not difficult to do; the 2020 NEC provides this direction and is instrumental in helping to prevent a fun day at the pool from turning into a tragedy. NFPA 70 the National Electrical Code® (NEC®) is now available in NFPA LiNK™, the association’s information delivery platform with NFPA codes and standards, supplementary content, and visual aids for building, electrical, and life safety professionals and practitioners. Learn more at nfpa.org/LiNK.   
A microphone

2023 National Electrical Code Aims to Make the World Safer, Collectively Through Public Feedback

As NFPA celebrates its 125th anniversary, we thank all of you for helping us protect this world, making it a safer place. We cannot be successful without your important contributions. One such example is the first draft of the 2023 NFPA 70 National Electrical Code® (NEC®), which posted publicly on June 28. Over 4,000 public inputs for the 2023 NEC were received and evaluated by the NEC Code Making Panels (CMP), producing the first draft of the standard. The next step in the NFPA Standards Development Process is the public comment stage. Between now and August 19, the public has an opportunity to review the 2023 NEC first draft and have their voice heard by submitting a public comment. If you did not submit a public input, now is the time to review the 2023 NEC first draft and become engaged in the process. While it would be difficult to elaborate here on all the topics for the 4,000-plus public inputs that were submitted, there are certainly some you would expect, and maybe a few you might not. Inputs were received on ground-fault circuit interrupters (GFCI’s) and arc-fault circuit interrupters (AFCI’s), which are common within each cycle and always generate a lot of discussion. There were also inputs introduced in the public input stage around cyber security and cannabis oil systems, topics that are tied directly to the changing world around us.  Whatever your passionate about, your voice needs to be heard. You have a right in the process; don’t let the 2023 NEC be fully developed without adding your public comment and expertise. While on the topic of your voice being heard, there is more needed than just commenting on the 2023 NEC. Now is the time to contact legislators to ask that the most current codes and standards are being utilized in your community. The NEC is developed in three-year cycles in which the latest safety needs and technologies are addressed and implemented. Operating on older cycles of codes and standards denies the public their right to safety. After all, “Development and Use of Current Codes” is one of the eight key components of the NFPA Fire & Life Safety Ecosystem that must all be utilized in conjunction to minimize risk and help prevent loss, injuries, and death from fire, electrical, and other hazards. As of June 1, 2021, there are only 11 states that have adopted the 2020 NEC, which is the most current published code, and we are well into development of the 2023 NEC. There isn't a better time than now to reach out to legislators and explain why it is so important that we adopt and utilize the most current, safest codes to achieve electrical safety. The NFPA Standards Development Process is recognized for being transparent and ensuring the ability for public input. The 2023 NEC is taking shape and accepting public comment through August 19. Whatever your role may be within the electrical industry, your voice needs to be heard. Not just regarding the 2023 NEC, but also requesting that legislators adopt the latest codes and standards in your local area. If the last year has taught us anything, it's that personal and public safety is key to our survival. It's a big world. Let's protect it together. NFPA 70 is now available in NFPA LiNK™, the association’s information delivery platform with NFPA codes and standards, supplementary content, and visual aids for building, electrical, and life safety professionals and practitioners. Learn more at nfpa.org/LiNK.

A Better Understanding of NFPA 70E: Comparing Electrical Fatalities in Specific Occupations

Each year I have given a summary of fatalities linked to the electrical industry. The U.S. Bureau of Labor Statistics (BLS) has not yet published the fatality numbers for 2020. My blogs have occasional pointed out that electrical fatalities do not just happen to those in electrical occupations. I decided to look at fatalities specifically due to exposure to electricity in various occupations.  The average electrical exposure fatalities (2011-2019) in construction and extraction occupations (75 fatalities), Installation, maintenance, and repair occupations (34 fatalities) and building and grounds cleaning and maintenance occupations (20 fatalities) account for a majority (79%) of the 153 annual electrical exposure fatalities. However, these occupations have people working in many sub-occupations. Who are the people dying from exposure to electricity while they are at work? The following chart shows the average electrical exposure fatalities for a specific occupation from 2011 through 2019.   Source: Bureau of Labor Statistics Those who read NFPA 70E®, Standard for Electrical Safety in the Workplace®, often get hung up on the phrase working on electrical equipment as a reason not address electrical safety in their workplace. Six of these nine occupations do not work on electrical equipment. They typically interact with it and often are not actively interacting with electrical equipment when they become a fatality. Five of these are on the OSHA list of occupational categories of employees facing a higher-than-normal risk of electrical accident. Many people say that, from these nine occupations, only the electrician is required to follow NFPA 70E. Follow that logic. Electricians are the vanguards of electrical safety. Why, then, are electricians being killed by the very thing they are the most knowledgeable about? Statistically electricians are possibly exposed to potential electrical hazards more often than most occupations. However, they are also supposed to know how to prevent their death while performing their work. Based on the starting assumption, they are the only ones who have been trained to recognize electrical hazards, and in the steps necessary to avoid being killed by those hazards. Yet, electricians consistently account for nearly 22% of all electrical exposure fatalities and 37% of electrical exposure fatalities in construction occupations. Another way to look at this is that an average of about 80 electricians die every year at work and about 25 of those deaths come from exposure to electricity. Supervisors at construction sites are often responsible for the day-to-day on-site safety and enforcement. However, eight supervisors per year are electrocuted while at construction sites. These are not good track records for the leaders in electrical safety. A concerning occupation is the grounds worker. It is difficult to fathom electrical fatalities in the occupation with the use of gas and battery powered equipment. Are they hitting electrical wiring not properly protected by the installation, are they using extension cords that are damaged, or are they exposed to outdoor electrical equipment that is not properly maintained? Fifteen deaths a year due to electricity is too many for this occupation. Around 30 people a year are killed by direct contact with an overhead powerline, but I was unable to find specific occupations listed in the BLS data base. However, tree trimmers, roofers and painters are common occupations associated with this type of fatality often due to the use of a ladder, pole extension or boom. In my experience, many HVAC technicians have not taken up the belief that electrical safety applies to them which may account for their fatalities. I expect that the electrical deaths to production workers is heavily tied to lack of proper equipment maintenance. NFPA 70E is written to provide protection for these unqualified workers when exposed to electrical hazards while working. All employers must implement an  electrical safety program before these fatalities are a thing of the past. NFPA 70E is concerned with electrical safety in the workplace for all workers. Regardless of your occupation there is the potential for a fatality due to exposure to electrical hazards. Electricians as well as painters must understand this and not only learn but apply the safety protocols that NFPA 70E outlines. Want to keep track of what is happening with the National Electrical Code® (NEC®)? Subscribe to the NFPA Network to stay informed of new content. The newsletter also includes NFPA 70E information such as my blogs.
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