Estimate of the Likelihood of Occurrence of an Arc Flash
Every electrical job or task we choose to involve ourselves in comes with a certain amount of risk. Our jobs as qualified persons in our respective fields is to be knowledgeable in the operation of the equipment we’re working on. This responsibility is tied to understanding the construction of the equipment we work on and with, which allows us to be able to recognize potential electrical hazards in the equipment and avoid them when they present themselves.
Jobs that require extensive troubleshooting or that test your knowledge of electrical systems and theory can be incredibly rewarding to those of us who take pride in our overall industry knowledge and problem-solving skills. However, there are steps that we all must take before we dive into our work that are equally systematic and have an importance that increases exponentially based on the number of personnel involved in the work. I’m speaking about the Hazard Risk Evaluation Procedure.
I’m sure most of us in the electrical field are familiar with doing risk assessments and evaluations, but I’ll provide a quick educational breakdown from NFPA 70E, Annex F for convenience. A qualified person would start by gathering all the information needed for the task and determining any limitations, including documenting known hazards associated with the tasks being performed. With each hazard comes a risk, so safety measures need to be assigned to mitigate the risk to an acceptable level. Further reading into Annex F, Table F.3 will outline the hierarchy of risk control methods, the last of which is PPE.
This brings us to the third video in the 70E changes for 2018. NFPA’s senior electrical engineer, Chris Coache takes the time to break down a table that has been misused in the past [Table 130.5(C)]. Coache talks about how this table has been used in order to determine whether or not a person needed arc flash PPE and goes on to explain that the table’s intended use is quite different. He also does an excellent job breaking down the exact meaning of the terms used in the table. An important point to mention is that “No” on the table does not mean that there is no risk. The “No” here refers to the “low potential for a likelihood of an occurrence of an arc flash” and that a qualified person would still need to perform their initial risk assessment to verify the nature of their work environment.
So take a moment to view and really understand this video and prepare to integrate this table and others found in 70E to your future projects.