What does HRC 2 mean, and why are arc flash ratings in calories?
HRC 2 is the old name for what NFPA 70E now calls PPE Category 2: clothing with an arc rating of at least 8 cal/cm², worn with the face shield or hood, hard hat, safety glasses, hearing protection and leather footwear the category lists. HRC stood for Hazard/Risk Category and ran from 0 to 4 in the 2012 and earlier editions of NFPA 70E; the 2015 edition dropped HRC 0, renamed the rest PPE Category 1 to 4 and kept the same minimum arc ratings (4, 8, 25 and 40 cal/cm²), so a garment labeled HRC 2 and one labeled CAT 2 mean the same thing. The ratings are in calories per square centimeter because that is how the heat of an arc is measured: incident energy is the heat landing on a surface a working distance away, in calories (a unit of heat) per square centimeter (the area it lands on). 1.2 cal/cm² is the onset of a second-degree burn on bare skin, the arc rating of a fabric (ATPV) is the incident energy at which there is a 50 percent chance of enough heat passing through to cause that burn, and a garment is chosen so its rating meets or exceeds the incident energy on the equipment label or the category’s minimum. Portwest prints the ATPV and the category on every arc-rated garment here.
Portwest Bizweld Work BZ31 FR Cargo Pants, ATPV 11.2 cal/cm², CAT 2ATPV and NFPA 70E category as Portwest states them (Portwest data)Why the name changed and the number did not. “Hazard/Risk Category” mixed two ideas, the heat the arc could deliver (the hazard) and the chance of it happening (the risk), and the category tables in the older editions carried both. In 2015 NFPA 70E separated them: the likelihood of an arc became its own step in the risk assessment, and the clothing table became a list of PPE Categories defined by the minimum arc rating alone. The minimums were carried over, so a label printed before 2015 that reads HRC 2 is read today as CAT 2, 8 cal/cm², and the garment is as useful as the day it was made. Calories stayed because the test that produces the rating (ASTM F1959, the arc exposure of a fabric panel with heat sensors behind it) reports heat flux in cal/cm², and the equipment label that tells the worker the incident energy at the working distance is in the same unit, so the two numbers can be compared directly: a 12 cal/cm² label needs an arc rating of 12 or more on the outer layer or the layered system.
The categories, old name and new
Minimum arc rating of the clothing in each, unchanged across editions.
Reading the figures on a Portwest page
- ATPV, not EBT: Portwest reports an arc thermal performance value on every FR garment, the incident energy at a 50 percent probability of a second-degree burn through the fabric; a fabric that breaks open before that point would be reported as EBT (energy breakopen threshold) instead, and the lower of the two is the arc rating.
- HAF: the US data sheets print the heat attenuation factor beside the ATPV (FR511: ATPV 8.2 cal/cm², HAF 69.1 percent), the share of the arc’s heat the fabric blocked in the same test.
- Category: Portwest writes CAT 1 to CAT 4 with the ATPV; older Portwest labels and competitors’ pages may still read HRC 2, and the two mean the same minimum.
- Layering: the category is met by the outer layer or by a layered system tested together; two 8 cal/cm² garments worn together are not automatically 16, and Portwest publishes no layered-system ratings.
- Dual listing: most Bizflame and Bizweld garments list NFPA 2112 (flash fire) with NFPA 70E and ASTM F1506 (arc), which are different tests; the calorie figure belongs to the arc test only.
The CAT 1, 2 and 4 garments on the Neese and Radians pages
Radians describes its VolCore and Neese FR workwear as self-extinguishing and non-melting when exposed to flame. The fabrics on this site are the ones the product pages name: 4.5 oz Nomex (CAT 1, 4.6 cal/cm² on the Neese bib pants), 7 and 9 oz Indura and 7 and 8 oz Ultra-Soft 88/12 cotton-nylon (CAT 2, 8 to 11.5 cal/cm²), 5.5 oz Westex DH (CAT 1, 6.6 to 6.8 cal/cm² on the Radians FR vests) and 5.7 oz Westex DH Air (CAT 2, 8 cal/cm²), 100 percent cotton FR sateen and cotton-nylon twill on the Radians VolCore line (CAT 2, 8.9 to 11 cal/cm²), modacrylic blends (CAT 1 at 5.1 to 5.4 cal/cm² on the vests, CAT 2 at 8.6 to 9.6 on the shirts and coveralls, and CAT 4 at 52 cal/cm² on the Neese VM7JBL3 insulated jacket) and 9.6 oz Polartec Power Grid FR fleece (20 cal/cm² on the Neese balaclava). Each page lists the standards Radians prints: NFPA 2112, NFPA 70E, ASTM F1506 and UL certification where they apply, with ANSI/ISEA 107 Type R Class 2 or 3 on the hi-vis FR shirts and vests. Radians’ heated gear is listed as not FR rated; its self-extinguishing (SE) vests are ASTM D6413 only, with no arc rating.
Neese and Radians VolCore product pages (radians.com, radians.com, fetched Nov 8 2026)Neese and Radians FR fabrics on this site, with the arc rating and category each page prints
| Fabric | Weight | Arc rating | Category | Standards listed |
|---|---|---|---|---|
| Nomex (Neese) | 4.5 oz | 4.6 cal/cm² | CAT 1 | NFPA 70E; UL certified |
| Indura treated cotton (Neese) | 7 oz and 9 oz | 8 to 11.5 cal/cm² | CAT 2 | NFPA 70E; UL certified; NFPA 2112 on the shirt |
| Ultra-Soft 88/12 cotton-nylon (Neese) | 7 oz and 8 oz | 8.5 to 9.87 cal/cm² | CAT 2 | NFPA 70E; UL certified |
| Westex DH (Radians FR vests) | 5.5 oz | 6.6 to 6.8 cal/cm² | CAT 1 | NFPA 70E; NFPA 2112 and UL certified where printed; ANSI/ISEA 107 Class 2 or 3 |
| Westex DH Air (Neese shirt, Radians vests) | 5.7 oz | 8 cal/cm² | CAT 2 | NFPA 2112; NFPA 70E; UL certified; ANSI/ISEA 107 Class 2 or 3 |
| 100% cotton FR sateen and 88/12 twill (Radians VolCore) | 6.5 to 9 oz | 8.9 to 11 cal/cm² | CAT 2 | NFPA 2112; NFPA 70E; ASTM F1506; UL certified |
| Modacrylic blends (Radians, Neese) | 5.8 to 7.75 oz | 5.1 to 9.6 cal/cm² | CAT 1 or 2 | NFPA 70E; ASTM F1506; ANSI/ISEA 107; NFPA 2112 on the Neese coverall |
| Polartec Power Grid FR fleece (Neese balaclava) | 9.6 oz | 20 cal/cm² | CAT 2 | ASTM F1506; NFPA 70E; NFPA 2112 |
| Neese VM7JBL3 insulated hi-vis jacket, 7 oz modacrylic | 7 oz | 52 cal/cm² | CAT 4 | NFPA 2112; NFPA 70E; ASTM F1506; UL certified; ANSI/ISEA 107 Class 3 |
Source: The Neese and Radians product pages on radians.com, fetched Nov 8 2026; the Arc Rating, Arc PPE Category, Material and Standards lines on each product page on this site. Radians prints ATPV figures only; the garment label governs.
Questions people ask
What does HRC 2 mean?
Hazard/Risk Category 2 in NFPA 70E editions through 2012: arc-rated clothing with a minimum arc rating of 8 cal/cm² plus the listed face, head, hand and foot protection. Since 2015 it is called PPE Category 2 (CAT 2) with the same 8 cal/cm² minimum.
Is HRC 2 the same as CAT 2?
Yes for 1 to 4: NFPA 70E-2015 renamed the Hazard/Risk Categories PPE Categories and kept the minimum arc ratings (4, 8, 25, 40 cal/cm²). HRC 0 was removed.
Why are arc flash suits rated in calories?
Because the heat of an arc is measured as incident energy in calories per square centimeter, the ASTM F1959 test that rates the fabric reports in the same unit, and the equipment label the worker reads is in that unit too, so the three compare directly.
Is a 12 cal/cm² garment CAT 2 or CAT 3?
CAT 2: it meets the 8 cal/cm² minimum and falls short of the 25 cal/cm² CAT 3 minimum. Portwest lists its 8.2 to 24 cal/cm² garments as CAT 2 for that reason.
What is the incident energy at the arc flash boundary?
The incident energy at which a second-degree burn begins on bare skin; it is the threshold the arc flash boundary is drawn at and the burn the ATPV test measures the fabric against.
When should you wear an arc flash suit?
When the exposure is above what everyday arc-rated clothing covers: NFPA 70E PPE Category 3 (25 cal/cm² minimum, the old HRC 3) and Category 4 (40 cal/cm², HRC 4) call for an arc flash suit with a hood; under the incident energy method the suit is worn whenever the label figure exceeds the rating of the shirt-and-pants layers. Portwest’s FR garments print the ATPV and the category on each page.
Which PPE protects against arc flash?
Arc-rated clothing with an ATPV or EBT at or above the incident energy at the working distance (or the category minimum: 4, 8, 25, 40 cal/cm²), with an arc-rated face shield and balaclava or a suit hood, hard hat, safety glasses, hearing protection, leather or arc-rated gloves and leather footwear; rubber insulating gloves and insulated tools cover the separate shock hazard.
What is arc flash category 0?
The old HRC 0, for exposures below 1.2 cal/cm² where non-melting natural-fiber clothing was enough; NFPA 70E dropped it in the 2015 edition when HRC became PPE Category, so the current table runs 1 to 4 and says “no arc flash PPE required” where 0 used to be. A garment marked HRC 0 has no arc rating.
How much does an arc flash suit cost?
The band on this page shows the price on each Portwest arc-rated garment at the quantity listed, and the Category 3 and 4 suits and hoods are on the arc flash selector linked above; we sell nationwide. The figure that sets the price is the ATPV the fabric system reached under ASTM F1959, which is why a 40 cal/cm² suit costs more than an 8 cal/cm² shirt.
What is the minimum arc rating for CAT 2?
8 cal/cm², under NFPA 70E Table 130.7(C)(15)(c): an arc-rated long-sleeve shirt and pants or coverall rated at least 8, with an arc-rated face shield and balaclava or an arc flash hood, hard hat, safety glasses, hearing protection and leather footwear. The old HRC 2 carried the same 8 cal/cm² minimum, so a shirt labeled HRC 2 or CAT 2 meets the category either way.
The ratings, test results and standards shown here are the manufacturers' published values, reproduced as published. Nothing on this page is a recommendation by Bayshore Safety that any product is suitable for a particular task, hazard or workplace. Selecting safety products and protective equipment is the responsibility of the end user and the employer, based on their own hazard assessment and the regulations that apply to their work. Confirm every value on the manufacturer's own documentation before use.