Just a few years ago, the standard was comprised of five "hazard-risk" categories that outlined the required personal protection equipment (PPE) a worker had to wear to reduce electrical arc flash exposure. But today's version addresses hazard and risk separately, to help site managers and technicians better understand the dangers of energized work via a series of linear steps.
For this process to work, all parties must have an understanding of "hazard" and "risk."
- A hazard is the calculated heat energy at any given point of an electrical system and is used to determine the correct level of PPE. A hazard is either present or not present.
- Risk is the combination of likelihood and severity of a potential injury while performing the work task.
To further illustrate risk, consider an electrician at a manufacturing plant operating a circuit-breaker disconnect on a 480-volt low-voltage motor control center (MCC) with the enclosure door closed. The likelihood of a shock injury is near zero, with no exposure to energized conductors, and the likelihood of an arc flash event is extremely low. Now consider a task where the electrician is testing or troubleshooting using a multi-meter to test phase voltages with the MCC enclosure door open. The hazard is the same, but the risk of electrical injury from shock hazard and arc flash is higher because the electrician is exposed to energized conductors.
Know the chances of an arc flash with a thorough risk analysis
NFPA 70E requires an exhaustive risk assessment before energized work begins — a great safety advancement. A risk assessment reviews electrical hazards, the planned work task and the protective measures required to maintain an acceptable level of risk. In practice, this means scheduling a work-plan meeting to discuss and document issues for the task at hand, the tools required, maintenance history of the equipment, test records of the equipment requiring energized work and the calculated amount of heat-energy exposure. The following summarizes the steps technicians should follow before performing energized work:
- Characterize the hazard or the electrical process involved.
- Identify the energized work to be performed.
- Define failures that could result from exposure to electrical hazards and the potential for harm.
- Assess the severity of the potential injury.
- Determine the likelihood of the occurrence for every hazard. This includes consideration of the resulting impact of possible human error based on the planned work task, such as a tool dropped near energized conductors at a worker's feet.
- Define the level of risk for the associated hazard.
- Wear appropriate PPE as determined during the hazard analysis. If the risk is too great, do not perform the energized task.
"The changes result in a clearer understanding of energized work and help reduce electrical incidents."
David B. Durocher, global mining, metals, and minerals industry manager
We're all human… and NFPA 70E takes that into account
One new and important aspect of NFPA 70E's prescribed risk analysis is the recognition of human error, as seen in step five, above. Per the standard, "Risk assessment procedures shall address the potential for human error and its negative consequences on people, processes, the work environment and equipment." With that, standard users should not only look to have a detailed process for performing energized work, but also maintain some method of quantifying human error.
In my opinion, accounting for error is an important addition to this evolving standard. To this end, some organizations require the issuance of energized work permits that account for the human element. This puts the onus on site leadership to double-check every detail before giving energized work the go-ahead, ensuring an extra level of business accountability. If work involves unacceptable levels of hazard and/or risk, a decision to perform the work during a future planned outage can be made.
Leadership must take the lead on safety
NFPA 70E is an industry-consensus guide, not binding law, so it's up to an individual business to choose to implement a site-specific electrical safety program. And it's important to note that industries do exist where turning off the power can lead to more severe problems. There are instances in the oil and gas industry, for example, where turning off the power can lead to a greater hazard than working on energized equipment. That said, I believe it's in everyone's best interest to wait for a planned future outage whenever possible instead of working on energized electrical equipment.
Of course, leadership teams have the right to make their own choices. While one group may choose to issue energized work permits, another may skip that step, which is completely within its purview. However, organizations that forego work permits can pay a price. If someone is injured or killed during energized work, regulatory organizations such as the Occupational Safety and Health Administration (OSHA) or the Mine Safety and Health Administration (MSHA) may require an explanation as to how the work was allowed and ask for detailed safety program documentation, including a work permit.
Beyond the standard, new technologies support recent trends of performing energized work outside a defined NFPA 70E flash-protection boundary. Site managers can look to network-connected devices, such as motor management relays, partial discharge on-line monitors and motorized racking technologies, to gather the information they need to troubleshoot electrical systems without requiring workers to suit up and work on energized equipment.
To increase safety, follow NFPA 70E
While it's always better to wait for a planned outage to work on electrical equipment, that's not always an option. Should you need to perform energized work, be sure to identify the hazards and risks and complete a thorough risk analysis that considers all potential risks, including human error. With a clearer understanding of the consensus standards and maintenance/troubleshooting requirements of a defined energized task, you can do more to advance a safety culture at your site, helping to reduce the chances of future shock and arc flash events.
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