Hugh, maybe you can help us to clarify this point in our workplace...we have performed incident energy analysis since 2005, and have labeled virtually all of our primary, and secondary equipment including disconnect switches and electrical panels. We use AR clothing and PPE at all levels above 1.2cal/cm2, but as of now, we allow employees to wear what we call "minimal PPE" for such work less than 1.2cal/cm2. That minimal PPE includes safety glasses, voltage rated gloves, hearing protection, and 100% cotton socks, underwear, long sleeve shirt, and long pants. According to my understanding of the 2018 NFPA 70E, such apparel is acceptable for performing work commonly rated well below 1.2 cal/cm2, correct? Additionally, we have had a question come up in regards to when our employees wear their AR coveralls...must they also wear their 100% cotton long pants under the coveralls, or can they wear 100% cotton shorts? I have my thoughts, and would prefer they wear the long pants for a greater measure of protection, but, is there anything documented anywhere in the standard that would specify that shorts may not be used underneath our AR coveralls? Thanks in advance for any assistance you may be able to provide.
Long underwear would not be needed if the outer layer exceeds the arc exposure. We do support your use of the old HRC 0 minimum underneath. I personally prefer to see all electricians and line workers in 100% AR daily wear to eliminate the risk of ANY ignition. Ignition kills about 50% of the time. Under protection only kills 5% of the time. We are pragmatists at e-Hazard and want human performance to be at its peak. Reducing the risk, reducing the number of decisions and chance for error is as important as good engineering or good arc ratings.
I see NO reason to prevent shorts under AR coveralls IF they are non-melting and the coveralls meet or exceed the hazard expected. Sweat can reduce protection in many fabrics so we recommend not over protecting as much as not cutting corners when there is an ignition risk.
On the note of an employee wearing a cotton under layer beneath overalls, I have received a question about an employee that wants to wear a light pullover jacket that is a cat 2 but does not want top wear the long sleeve cat 2 shirt. He wants to know if he can wear just the pullover and a cotton tee and be compliant and keep the company compliant as well. Do you have any insight for me on this instance?
As Hugh mentioned, if the light pullover exceeds the arc flash energy hazard then theoretically nothing else is needed underneath. Alternatively, you can use non-melting clothing but Hugh has raised the risk of ignition in his reply. Melting substrates are STRICTLY prohibited.
With all the theory out of the way, here are my thoughts: As a field worker, I am opening / closing panel doors, switching, voltage measuring etc. all the time. I do not "change" clothing arrangements (such as shirts, reflector vests, and pants). The BEST protection is the one that you "don" when you get to work and forget about it. Changing clothing opens us up to human factors considerations that increases the risk. We don't want to make any worker uncomfortable, but more importantly, we don't want to hurt anyone.