PPE Level 1 = up to 4 cal/cm2; PPE Level 2 = up to 8 cal/cm2; PPE Level 3 = up to 25 cal/cm2; PPE Level 4 = up to 40 cal/cm2
What you wrote is from OLD NFPA 70E standards and IEEE 1584. It is commonly used in the field but not in NFPA 70E, and 2015 makes it improper to use that idea. The PPE Levels are ONLY applicable when you use the Tables for your Risk Assessment.
This is a common issue in the field.