From time to time we receive questions/comments on published articles. One such case is an email from a “concerned worker” in reference to an article posted on the OH&S website in 2011 regarding the importance of PPE and it’s proper usage.
I wanted to thank you for your article from 2011. You mentioned in your article that its best to use class 0 1000volt instead class 00 500volt gloves for 480 volt systems because 480 ofter exceed that. I have had to convince some people why I chose class 0 over the class 00 for 480. It was believe the voltage listed on the glove was only for nominal, and not actual voltage. I actually had to explain the difference in the 2 and that the gloves are based on the actual voltage a person will be exposed to and not just the nominal design of the system. Wish I could find more info in writing to show this to people.
From a shock perspective Class O vs. OO is little difference. Sometimes you could have overvoltage and surpass the 500V but you are right it is nominal voltage. Most choose Class O for two reasons: Class O is thicker so they last longer.
Class O is better in arc flash because of that thickness. If you are working 120V-240V Class OO is fine. On 480V I recommend Class O. And Black or Blue are the most protective color for arc flash in research so far.
We cover this very issue in our NFPA 70E class. We are happy to answer similar questions about electrical safety and related issues.