Hi ....someone can help me?

If I had a equipment with 11cal/cm2 as a result of an arc flash study, can i use a 12cal/cm2 arc flash suit and comply NFPA 70E ? or i have to use a 25 arc flash suit?

I might be missing something but, yes, you can use a 12 cal suit (with a number of other provisos that must accompany the PPE alone).

As long as the PPE is rated for >11cal/cm^2, yes. This would include all the PPE including baclava, face shield, etc.

See 70E Annex H for some guidance.

Yes, if you're at the working distance at which the incident energy was calculated you would meet 70E requirements.

However, your company's Electrical Safety Procedure determines which form of PPE information is included on the arc flash label (1. incident energy, 2. minimum arc rating of clothing, 3. highest required PPE level or 4. highest HRC) and how that information should be interpreted by the employee.

Further to what A King says - if the company has standardized on certain levels of PPE, and puts level 3, or 25 cal/cm² on the label, then you need to use 25 cal/cm² rated PPE.

This is why you do an arc flash study. You may also wish to do a risk analysis to look closer at the actual task. If it is performed at a greater distance than the calculated "working distance" you might be able to reduce the PPE level. I never recommend doing any task with risk of ignition in flammable clothing. Just use something with the arc rating you will be exposed to. jGhrist points out something important also. Never put something on the labels you are not required or are not going to do. Having 12 cal and HRC3 is never recommended and a misunderstanding of NFPA 70E that was perpetuated by IEEE 1584-2002. It will be corrected in the next version and most software companies have in corrected now. HRC's and calculations don't mix. See Annex H.3 in NFPA 70E 2012

Thanks for all of you !!