HRC & NFPA 70E Explained

Your guide to understanding



HRC Hazard Risk Category Levels Explained


In its most basic form, HRC level 1 is for low risk environments and HRC 4 is for the highest risk environments.

The HRC level is determined by the minimum amount of calories per square centimetre (ATPV or Cal/cm2) an FR garment must pass with a 50% probability of a 2nd degree burn occurring The higher the ATPV, the higher the HRC level attained, and the greater the protection.

The following HRC level chart / table /matrix shows minimum ATPV value that must be achieved in order to meet the next level of HRC.


Hazard Risk Category Common FR clothing at this level Minimum ATPV (Cal/cm^2)
HRC 1 FR shirt and FR pants; Or FR coveralls; Single base layer of FR protection 4
HRC 2 FR shirt and FR pants; Or FR coveralls; Single base layer of FR protection 8
HRC 3 Single layer of garment layering to exceed 25 Cal 25
HRC 4 FR under garments (undershirt, underwear), FR shirt, FR jacket/coat, FR pants, and FR coveralls; FR under garments (undershirt, underwear), FR shirt, FR pants, multi-layer flash suit; 3-4 or more layers of FR protection are required 40

NOTE: Layering generally provides more protection than the sum total of the ATPV values of the individual garments being layered. However, this needs tested for each specific garment being layered, and thus is never explicitly included in layered calculations.





The National Fire Protection Agency (NFPA) created NFPA 70E, a Standard for Electrical Maintenance Personnel.

NFPA 70E standard was the first nationally recognised standard for electrical safety in the United States.

The first edition was released in 1976 at the request of OSHA to help provide consensus on electrical safety standards. NFPA70E is upgraded annually.

In 2015, NFPA70E will be mandated by OSHA in the United States.

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