Can you use an 8 cal/cm2 suit for a 8.2 cal/cm2 arc flash hazard?
- Thread starter duck-dude
- Start date
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I wouldn't worry about it one bit. The calculations are very conservative. But no doubt some who are more OCD would worry.
Keep this in mind.
The calculations tell you where you have a 50% chance of getting third degree burns. What will a slight change in incident energy do that is worse?
- Location
- Illinois
- Occupation
- retired electrician
What are you doing that you can justify energized work?
David Castor
Senior Member
- Location
- Washington, USA
- Occupation
- Electrical Engineer
By the letter of NFPA 70E, 8 cal/cm2 PPE would not be sufficient for an 8.2 cal/cm2 incident energy. As a practical matter, I personally wouldn't be concerned. The incident energy equations are not terribly accurate, are generally conservative, and require a lot of assumptions. Calculating IE to a tenth of a calorie implies greater accuracy than is really possible, imo.
But if something were to happen, even if it might not have been prevented by higher rated PPE, you would be stuck trying to explain why you used PPE that wasn't rated for the incident energy. That is a "how many zeros would you like on this settlement check" sort of losing proposition.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
That depends on the out come of the risk analysis you performed.
PPE does not prevent injury, it simply minimizes it. Incident energy values are usually reported as worst case, but the actual work may be occurring under less severe conditions, such as being further away than the standard 18". The most typically time this type of discussion occurs is when you need to verify a de-energized source, particularly if the level is above 40 cal/cm2.
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
If you are the employer. OSHA will come to bite if the Rating of the safety equipment is not up to the potential calculation. Could suggest that a recalculation be done for an "as installed" as a couple of feet of wire more or different equipment than estimated for can make up that very marginal difference. But as it is stated and or a posted ARC rating, you would be required to provide the next level of protective equipment even though it is a huge jump in protection in terms of cal/cm2 , or face the potential of fines and in a worse case criminal neglect prosecution. (Not a lawyer but seen to much litigious mentality out there. I'll sue you for getting burned when my coffee spills on me due to my own stupidity.)
you are not the employer what does it matter, you are not footing the cost of the PPE, and your responsibility might be to simply report the required PPE per calculated incident energy.
As others have stated a ".2" over the max protection of a Cat2, in reality might be not ever reached given varied incidences that might cause an event.
you are not the employer what does it matter, you are not footing the cost of the PPE, and your responsibility might be to simply report the required PPE per calculated incident energy.
As others have stated a ".2" over the max protection of a Cat2, in reality might be not ever reached given varied incidences that might cause an event.
If you had a 8 CAL long sleeve rated shirt then that and the 8 CAL Suit would be more then sufficient. My company purchased 8 CAL long sleeve shirts & pants but with the better material that stays Cooler during the summer went to 11 Cal . Years ago we were told that CAL rated shirts worn under CAL rated suits, hoodies or jackets add up. In other words a 8 CAL shirt worn under a 12 CAL jacket would provide 20 CAL. Should wear cotton or CAL rated T shirts for extra protection .Work also told us to only wear 100% cotton socks but think I never found socks made with more then 75% cotton.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Do not mix Categories and Calculations. You either choose PPE using the NFPA 70E tables or you perform calculations to determine the available incident energy.
To make PPE selection somewhat easier, many companies have include a grouping of PPE that mimics the NFPA 70E tables exactly, while others have a hybrid scheme. For example, the ability to use Category 2 PPE up to the tested rating of its individual components and not to exceed 12 cal/cm2.
To make PPE selection somewhat easier, many companies have include a grouping of PPE that mimics the NFPA 70E tables exactly, while others have a hybrid scheme. For example, the ability to use Category 2 PPE up to the tested rating of its individual components and not to exceed 12 cal/cm2.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
About 15years ago, NFPA70E changed their position and only allowed "adding" calories ratings if the clothing manufacturer allowed it. Like series rated breakers, nobody tests their stuff with competitors.
Thanks for this great information. My company like most others will generally purchase the lowest quoted price. Every year we had PPE from different companies. We preferred the CAL rated blue jeans with a large cargo pickets but not every manufacturer did not offer them. They also had problems when they asked companies if the thread for company logo, name & our name on our CAL rated long sleeve shirts was an approved ( guess non flammable material ) or had a CAL rating. Forget but one company thought that Kavlar was. Of course the going back & forth between several companies pushed back our yearly purchase. Cracked me up that my well over $100 CAL nylon zipper Hoodie had 5 separate tags marked "do not remove ".