FR vs Arc-Rated Clothing: What Buyers Need to Know

“FR” and “arc-rated” appear side by side in almost every workwear catalog, and buyers often treat them as synonyms. They are not. One describes how a fabric behaves in a flash fire; the other describes tested performance in an electrical arc. Specifying the wrong one can leave a crew unprotected.

What FR means

Flame-resistant (FR) fabric is designed to self-extinguish and resist ignition. Treated cotton, FR denim and inherent modacrylic blends are common. The relevant industrial standard is NFPA 2112, which uses an instrumented manikin test to confirm that predicted body burn stays at or below 50% during a short-duration flash fire.

NFPA 2112 clothing is typical in oil and gas, chemical processing, and any environment where a flash fire is the primary hazard.

What arc-rated means

Arc-rated clothing is tested for thermal performance in an electrical arc. The garment receives an arc rating measured in cal/cm², expressed as ATPV (arc thermal performance value) or EBT (energy breakthrough threshold). The test standard is ASTM F1959, and NFPA 70E uses the results to assign PPE categories.

An arc rating is a number, not a yes/no label. A 12 cal/cm² shirt and a 40 cal/cm² suit are both “arc-rated”, but they protect against very different incident energies.

The key difference

A garment can meet both: many arc-rated shirts are also NFPA 2112 compliant. But an NFPA 2112 garment without an arc rating should not be used for electrical work.

Reading the label

Look for:

• The standard and year: NFPA 2112, ASTM F1506, NFPA 70E
• The arc rating in cal/cm² for arc-rated garments
• Care instructions, because FR performance depends on proper laundering
• A tracking code that links the garment to a production lot

If a supplier cannot state the arc rating, the garment is not suitable for electrical tasks.

Matching ratings to the hazard

For arc flash, the arc rating must meet or exceed the incident energy from your arc flash study, following NFPA 70E. PPE categories are a shorthand:

• CAT 1: 4 cal/cm²
• CAT 2: 8 cal/cm²
• CAT 3: 25 cal/cm²
• CAT 4: 40 cal/cm²

Categories are useful for planning, but the study result always wins. A site with 9 cal/cm² incident energy needs a garment rated at least 9 cal/cm², so it would move to the next available rating above CAT 2.

Layering rules that are easy to get wrong

• Every layer worn in the hazard zone must be FR or arc-rated, including jackets, hoodies and rain gear.
• A non-FR jacket over an FR shirt defeats the protection in a flash fire.
• Base layers should be FR or natural fibers; synthetic meltable fabrics under FR clothing can increase burn injury.
• More layers do not automatically mean a higher arc rating; the system must be tested.

What to ask a supplier

1. What standard does this garment meet, and can you send the test report?
2. What is the arc rating, and is it ATPV or EBT?
3. Are the trims, zips and threads FR or arc-rated?
4. What laundering has the garment been tested to?
5. Can you supply FR outerwear and rain gear that match?

Bottom line

Use NFPA 2112 FR clothing for flash fire hazards and arc-rated clothing for electrical work, choosing a rating that meets or exceeds your incident energy. When in doubt, specify a garment that carries both certifications and document the decision in your PPE program.

Our FR clothing range includes NFPA 2112 shirts, pants, coveralls and jackets, plus arc-rated layers up to CAT 4, with test reports and lot traceability.