Just the other day I was speaking with another arc flash professional and the question was asked, “Why does the NFPA 70E allow for companies to use the tables, knowing that some companies cannot guarantee they meet the parameters laid out in the tables?”
The answer to this quesiton is unknown, however there are companies using the tables as guidelines for employee arc flash protection and these employees may be at risk.
The 2015 NFPA 70E, article 130.7(C)(15)(A) states that the tables can be used in lieu of an arc flash analysis, but there are requirements that must be met:
- The first requirement is that the specific tasks must be listed;
- Secondly, power systems’ available short-circuit current must be at a maximum of the listed kA short-circuit current listed for the specific equipment;
- The third requirement is that the fault clearing time must be no longer than the listed fault clearing time for the specific equipment;
- And lastly, the working distances must be met.
In all of my travels, when I am asked if a company can use the tables, I make sure to lay out the NFPA 70E guidelines and provide an honest answer. The reality of using the tables is that a company may not have the funds to pay for an arc flash study, and by using the tables they are not spending money. Another reality is that if there is an accident due to arc flash and an employee is hurt, those dollars saved by using the tables in lieu of an engineered study might be spent on workers compensation pay and lawsuits. The tables listed within the NFPA 70E are, in some cases, more than what is needed. And I imagine the NFPA is going to make sure that they are covered in case of an accident and a company says they used the tables listed in a National publication.
Using the tables listed in the 2015 NFPA 70E will protect employees against injury due to an arc flash accident, however make sure that you meet the parameters of the guidelines.