What are NFPA HRC’s? HRC is a numbering system used for arc-protective clothing. The HRC label externally identifies clothing or clothing systems (PPE) with different levels of protection. Industrial employers can use HRC’s to determine the FR clothing that should be worn by employees who are doing specific jobs or tasks. Workrite pioneered the use of external HRC labeling and it is now an industry standard.
The employer can look the task up in the NFPA 70E Task Tables, then look in the Task Table for the corresponding HRC required. These Task Tables are used by employers in lieu of calculating the actual arc energy exposure hazard of a specific job or task.
The different HRC numbers correspond with a minimum Arc Rating requirement for the PPE, stated in cal/cm² and called Arc Thermal Performance Value (ATPV). The HRC’s were established to cover a range of arc energy exposures by task. The HRC is only used when a hazard risk analysis is not performed by the employer and the actual exposure potential is not established. The HRC numbers, minimum PPE Arc Ratings (ATPV), and arc energy exposure ranges are as follows:
Task Table Numbers – HRC Levels Apply When Task Tables are Used
|Arc Rating Range (cal/cm²)||Exposure Range (cal/cm²)|
|1||4 or greater||1.2 to 4|
|2||8 or greater||4.1 to 8|
|3||25 or greater||8.1 to 25|
|4||40 or greater||25.1 to 40|
As you can see the arc rating is the minimum number or greater while the exposure range that it covers is from that same minimum number down to the next lower level. This provides a safety factor because the maximum exposure is never greater than the minimum arc rating. For example the HRC 2 exposure can never be greater than 8 cal/cm², and the HRC 2 arc rating range (ATPV) starts at 8 cal/cm².
You only use HRC numbers when you use the task tables. HRC numbers are not relevant when you’ve done the hazard risk calculations and have established the exposure energy (cal/cm²) of the job task.
You only use the arc rating (ATPV) number when you have done the hazard risk calculations and have established the exposure energy (cal/cm²) of the job task. Once you have the exposure energy (cal/cm²) calculated, then you simply match the garment’s arc rating (ATPV) to the exposure.
It is important to remember– it is the user’s responsibility to determine either the arc energy exposure they are protecting against or the HRC level they need.