Arc flash labels are a commonplace requirement for photovoltaic (PV) projects. However, arc flash studies and the resulting labels are sometimes treated as check-the-box exercises. In my experience as an engineer, I have found that questions are rarely asked regarding integration of PV arc flash labels into a safe, effective operations and maintenance plan. Engineers who charge by the man-hour can generate these labels all day long, yet they aren’t the ones tasked with donning PPE to perform hot work. A fundamental link is missing in terms of safety. Essentially, arc flash labels provide employees with critical PPE information when work must be performed near energized electrical equipment. But this could make hot work on energized electrical systems sound routine – and it shouldn’t be, ever. Consider this scenario that a safety expert presented to students during an electrical safety training class in Baghdad: There is heavy nighttime fighting. After shrapnel cuts power lines to a hospital, the emergency generators don’t start. Do you rush to splice the wires back together, hot, because lives are at stake, time is of the essence, and the task is relatively simple? The safety expert’s recommended response? An emphatic “no.” Unforeseen hazardous conditions could lead to worker injury or death and additional equipment damage in addition to prolonging the outage. The bottom line here for workers is to perform assigned tasks de-energized whenever possible. Fully inspect and test to determine the scope of work. Make the necessary repairs, check again, and then safely re-energize. No shortcuts. A Troubling Perspective Occasionally a client will say they do not want to see PPE categories above Level 3, which is troubling for two reasons. One, if a job requires live troubleshooting, Level 3 PPE may not adequately protect workers. Two, the client’s perspective excludes any mention of the other five levels of the hierarchy of controls (i.e., elimination, substitution, isolation, engineering controls and administrative controls), plus it disregards the fact that certain arc flash hazards may be built into a system based on equipment selection long before the engineer of record begins their design work. As most readers understand, PPE is a critical component of hazard protection for workers, but it is also their last line of defense. Employers that adhere to industry best practices use the other five levels of the hierarchy of controls to eliminate or mitigate identified worksite hazards, including arc flash risks. Regarding equipment selection, I recommend that organizations seek and fully consider guidance from reputable, experienced engineers. For example, we may suggest that instead of building a 4,000-kWac system, the company should split it into two 2,000-kVA medium-voltage transformers powering 2,000-kW inverters. Why? If the client chooses a single 4,000-kVA transformer feeding a single 4,000-kW central inverter, they are guaranteed extremely high AC and DC arc flash energies on at least one side of the overcurrent protective devices. How Bad is the Worst Case? Engineers will occasionally fixate on identifying worst-case scenarios, examining more factors than necessary. But once we know the worst case, what should we do with that information? While some peer-reviewed industry papers cover worst-case scenarios from every conceivable angle, two IEEE papers reference real-world testing results that indicate true arc flash levels are two to 10 times lower than those calculated by standard methods (see https://ieeexplore.ieee.org/document/9658515 and https://ieeexplore.ieee.org/document/10188331). Recently, I’ve seen client specifications for PV projects that require use of the Paukert method to calculate DC arc flash values. Some software packages offer users a choice between three major calculation methods (i.e., maximum power, Stokes/Oppenlander or Paukert). Unfortunately, a 2020 IEEE paper states that “none of the available DC arc-flash models are applicable for a PV plant” (see https://ieeexplore.ieee.org/document/9181477). No recommended industry calculation methodologies have been adopted at the time of this article’s publication. We can’t escape AC grid energy at any time of day, but we can escape most DC energy by avoiding noontime maintenance, even if avoiding peak power could result in longer clearing times by protective devices. ‘Routine’ Troubleshooting Industry articles mention that arc flash labels are useful when selecting PPE for routine troubleshooting work. Again, while it is essential for workers to use PPE based on their hazard exposure, employers must strongly consider adjusting work practices and system designs to eliminate any need for routine troubleshooting. Here is an example to help you understand what I mean. Few PV entities manage all the stages of a system’s life cycle (i.e., design, build, own and operate), which could explain their reluctance to invest in string monitoring versus the default design of zone monitoring only at the combiner-box or inverter level. Even with standard combiner-box monitoring, modern artificial intelligence systems can determine if a problem exists with one or more strings. Eventually, a site investigation will be needed to check every string in the combiner box because AI is not granular enough to do it, adding an hour or more to the on-site discovery time. Investing in additional instrumentation that more efficiently identifies problematic strings typically pays for itself by eliminating a “routine” safety hazard while also decreasing the number of truck rolls and employee time spent on-site. Some inverters now provide IV curve tracing as a built-in feature. Unlike humans, this test equipment does not get tired after a long day of work in extreme heat or cold, which is helpful in accurately identifying and reporting anomalies. A great number of AC circuit breakers in the main collection panels can be procured with full Modbus sensors and communication, which may sound like a luxury, but consider a worker who over-torques inverter cables at the circuit breakers. Localized heating begins to cause intermittent breaker trips, necessitating lengthy visits from an electrician to take multiple clamp-on meter readings. Now the cost may no longer seem excessive. If a bus voltage needs to be tested – a task that typically requires suiting up and opening the rear of a panelboard – why not spend $500 or less to install indicating lights and test jacks that are accessible from outside the panelboard? From my perspective, a sizable portion of the money invested in hardware for PV projects could be diverted to safety enhancements with no adverse impact on production or total capital costs. Beyond PPE, use elimination, substitution, isolation, and engineering and administrative controls to eradicate any need for routine troubleshooting. A change in mindset is all that is required. Two-Level PPE Systems The following table shows some typical arc flash energy levels for major PV project components based on a review of 12 different PV projects. Most of the projects were in the community solar space of 2 to 5 MWac and a 1.3 to 1.5 DC/AC ratio. Many facilities, recognizing the complexity of arc flash labels, have implemented a two-level PPE system. The first level is a Category 2 (8 cal/cm²) standard work uniform that also requires gloves, a face shield and other PPE as needed. The second is full Category 4 PPE for the rare occasions when Class 3 or 4 work is necessary. Without retraining, most employees can remember their regular uniform plus gloves and a face shield without issue. Since there is little variation in arc flash energy levels among similar PV projects – and they are all quite similar – it may be relatively easy to establish a common set of practical arc flash labels for a given fleet of solar projects. Looking at the table above, they should prohibit hot work on any AC equipment upstream of the string inverters. All DC equipment is in the realm of typical Category 2 work clothes. That lower energy risk can be further reduced by work practices and their timing. Conclusion Engineers can calculate short-circuit currents and produce arc flash labels at any time, but they aren’t frequently consulted to assist in converting their dedicated efforts into safe, effective work practices. Arc flash labels don’t provide any guarantees, and human performance is far more critical to safety than the presence of a few labels. Ideally, PV owners will continue to use arc flash labels while also developing work methods and investing in equipment to ensure worker exposure to energized system components is a rare occurrence – one that requires a thorough preliminary review and a written hot-work permit. About the Author: Joe Jancauskas, P.E., CUSP, PMP, has over 40 years of electrical power engineering experience, including 16 years in solar. He has been responsible for numerous arc flash studies as well as implementing an effective arc flash program for an electric utility.

The first four articles in this six-part series outlined the significance of an organizational safety management system (SMS) that involves all employees. They emphasized effective risk mitigation through a well-developed plan for continuous improvement, with a focus on human and organizational performance. This article highlights critical operational processes that must be thoroughly assessed and refined to support organizational safety. Every operational unit must take proactive ownership of its safety protocols and practices, actively integrating safety measures into all aspects of its operational processes. By integrating safety into daily routines, each unit fosters a culture of responsibility and prioritizes employee safety. This article also highlights key aspects from my experience in the electric power industry. We will follow the framework provided by ANSI/ASSP Z10-2019, “Occupational Health and Safety Management Systems,” which addresses the following areas relative to implementation and operation:

• Operational planning and control
• Identification of operational issues
• Operational risk assessment
• Change management
• Operational process verification
• Procurement
• Contractors
• Emergency preparedness

I encourage readers to consider topics not covered in this article – including operational process verification and emergency preparedness – to obtain a more comprehensive understanding of the principles associated with the Z10 standard. Operational Planning and Control This section of the standard emphasizes a crucial aspect of how organizations equip their employees for success. Rules and procedures. Let’s begin by discussing the implementation of rules and procedures in the workplace. As a consultant, I have consistently encountered missing or ineffective procedures and/or rules during organizational safety assessments. Safety rules that reference OSHA regulations hold little value if there are no clear procedures defining what is expected to comply with those rules. One example is stating in the safety manual that equipotential zone grounding is required without clearly explaining how to achieve it within all aspects of work. Rules and procedures must provide clear directions so that employees know what is expected of them and can successfully comply. Competency. Ensuring the competency of employees plays an extremely important role in an effective SMS. An employee isn’t necessarily competent just because they attended school or received specific training. Competency is based on the employee’s ability to demonstrate a specific skill on a regular basis, using all required safety procedures in response to identified hazards. I purposely included “regular basis” in the previous sentence because some employees can pass written and practical tests immediately after training but struggle when performing those tasks later in the field. Additionally, competency should never be solely based on field experience and time on the job. Although both are important factors, they must be paired with a structured method to ensure employee competency through the demonstration of proficiency. It is crucial to remember that this principle also applies when organizations promote employees to leadership positions. Seniority should never be the only reason to promote someone who will be responsible for safely leading others. Maintenance and inspection programs. These programs are essential SMS components that should encompass electrical and mechanical equipment as well as other critical systems that require regular maintenance to ensure safety. National codes, such as the National Electrical Safety Code and the National Electrical Code, emphasize the importance of electrical equipment maintenance for both employee safety and system reliability. Many organizations adhere to manufacturer recommendations for maintenance; however, some have neglected inspections and maintenance for years. When equipment and systems are not adequately cared for, the risk of hazards significantly increases, potentially impacting employees’ ability to work safely. I believe that strong maintenance and inspection programs are imperative for an organization to achieve safety success. Identification of Operational Issues The main directive of this section of the Z10 standard is to evaluate whether the organization has (1) conducted a thorough assessment of its work processes and (2) adopted improved methods, tools, equipment, installations, designs and technologies suitable for today’s workforce. As an industry consultant, I believe electric power organizations must stay informed about and adaptable to innovations that can enhance workplace safety and efficiency. An example I recently encountered involved employees working in a remote area with no access to radio or cellphone service. This is a serious operational issue, even if some workers view it as normal. Should an electrical contact or other serious injury occur, the affected employees would have little chance of receiving life-sustaining support. I consider this unacceptable. Known communication challenges require immediate operational evaluation and improvement based on available tools, equipment, rescue supplies and technology. Numerous organizations fall into the trap of accepting the status quo without questioning it, adopting a mentality of “this is the way it is.” This mindset fails to recognize the critical nature of regularly evaluating and improving the methods and practices that support employees, thus risking serious operational upsets. Organizational leaders should actively seek to identify areas for improvement, implement innovative strategies and foster an environment in which employees know their feedback is valued. Operational Risk Assessment Here is something else that leaders must consider: Have each of the organization’s operational units taken the necessary steps to identify high-risk jobs by asking, “What are the worst things that could happen on our worksites?” Let’s be honest: While many operational leaders acknowledge this concept, their discussions sometimes overlook employee safety. Earlier in this series, I explored the distinction between planned work and actual work. These two activities represent distinct realities in the workplace. Frequently, operational processes and discussions focus on how work is theoretically done, neglecting the actual execution by field employees. According to the Z10 standard, an operational risk assessment should consider organizational factors that can increase risk, such as production pressures, poor communication and lack of resources. Here is a possible scenario: A contractor has been hired to build a new substation for a utility. While on-site, the contractor receives a request for emergent work: replacing equipment in an energized substation located within 5 miles of the existing work. Should the contractor dispatch additional personnel with the necessary expertise to work in an energized substation, or should they assign the project to existing staff with limited experience in that environment? If this were a real scenario, many decisions would influence the answer. They are frequently made based on the project’s financial aspects for both the utility and the contractor, rather than the risks involved. Such situations often stem from a widespread culture of risk acceptance that overlooks the potential negative consequences of these decisions. Change Management Has your organization recently implemented a new work method or safety rule that has created confusion among employees, causing them to revert to previous practices? This is common in organizations that lack a structured strategy to effectively communicate and manage change. Operational units often communicate change during safety or operational meetings. Consider, for example, an organization that purchases a new distribution line recloser. The recloser is introduced during a safety meeting, where its basic functions and safety requirements are explained. Several days later, employees are tasked with troubleshooting an area where the new recloser is located, despite having little knowledge about its design, installation or operation. While changes are commonly introduced at safety meetings, my professional experience suggests that they are only effective when paired with employee skills training and proficiency demonstrations based on specific task requirements. After identifying significant opportunities to enhance their change-management processes, many large organizations have appointed personnel explicitly tasked with addressing them. Regardless of whether your organization has such specialized personnel, it is essential to clearly understand how change is identified, assessed and managed. This includes recognizing the potential impact of change on various operational units and ensuring that all team members are prepared to adapt. Effective management reduces resistance to change while also fostering safety culture growth within the organization. By actively involving all stakeholders and clearly communicating the reasons for change, organizations can more smoothly integrate new practices and policies. Procurement Does your organization effectively incorporate procurement into its safety and risk management planning? To illustrate procurement’s critical role, let’s continue examining the line recloser example provided above. In that scenario, the procurement department identifies a new line recloser that has been successfully adopted by several other utilities, as communicated by the sales team. The purchasing team decides to acquire 25 units for evaluation, aiming to determine whether the reclosers will perform as promised and enhance operational efficiency. However, a significant oversight occurs: no risk assessment is conducted prior to the acquisition, and there is no clear strategy to integrate the new devices into the organization’s existing operational framework. This could lead to implementation challenges, particularly if the new technology does not align with current processes or safety protocols. Scenarios like this one are common in organizations that fail to involve their procurement department in operational risk assessments and safety planning. This lack of collaboration can result in the purchase of new equipment that does not meet safety standards or operational needs, ultimately leading to unnecessary risks and complications in the field. To ensure a safer, more efficient operational environment, it is vital to implement a comprehensive approach that includes procurement in these discussions. Contractors It is also essential for utility organizations and contractors to establish a comprehensive safety management standard that effectively addresses the unique safety requirements of contractors, tailored to their respective risks. The Z10 standard emphasizes the necessity of developing a systematic approach to identify, assess and mitigate potential safety and health risks associated with contract work. This process enhances safety performance and fosters a proactive organizational safety culture. When engaging contractors, electric power organizations have historically adopted a somewhat hands-off approach. This traditional method typically involves evaluating incident rates, confirming insurance limits and mandating adherence to OSHA standards. However, my experience indicates that these measures alone are insufficient to effectively mitigate the risks a host organization may face, particularly in the event of a catastrophe. To address this, it is imperative to move beyond basic compliance. Organizations should conduct thorough prequalification processes, including assessing a contractor’s safety management system, past safety performance and safety training practices. Additionally, implementing regular safety audits and ongoing performance evaluations can help organizations ensure that contractors maintain high safety standards throughout the contract’s duration. Engaging in open communication and collaboration with contractors regarding safety expectations can lead to a deeper understanding of risks and the shared responsibility for safety outcomes. By adopting a more integrated and rigorous approach to contractor safety management, utility organizations can significantly enhance their ability to safeguard their employees and the public from potential hazards. Summary This article emphasizes the importance of thoroughly assessing and refining critical operational processes to embed and support safety within utility organizations. It highlights the ANSI/ASSP Z10-2019 standard as a framework for implementing an effective SMS, focusing on areas such as operational planning, operational risk assessment, change management, procurement and contractor oversight. By fully integrating safety into all aspects of operations and fostering a culture of accountability, organizations can better protect their workforce and improve system reliability. About the Author: Pam Tompkins, CUSP, CSP, is president and CEO of SET Solutions LLC. She is a 40-year veteran of the electric utility industry, a founding member of the Utility Safety & Ops Leadership Network and past chair of the USOLN executive board. Tompkins worked in the utility industry for over 20 years and has provided electric power safety consulting for the last 25 years. An OSHA-authorized instructor, she has supported utilities, contractors and other organizations operating electric power systems in designing and maintaining safety improvement methods and strategies for organizational excellence.