CAT 2 vs CAT 3 vs CAT 4: Arc Ratings Explained
More is not always better — paying for CAT 4 when CAT 2 is the spec usually means less comfort for no added safety. Here is how to read arc ratings.
July 10, 2025 · 5 min read · by Summit Work Apparel®
If you have ever looked at FR garment spec sheets and seen CAT 2, CAT 3, and CAT 4 listed side by side, it is natural to ask: should I just buy CAT 4 and be done with it? Short answer: usually no. Here is the why.
What an arc rating actually is
Arc rating is measured in cal/cm² — the energy needed to cause a second-degree burn through the fabric. The CAT system boils those numbers down to four buckets:
- CAT 1 — 4 to 8 cal/cm²
- CAT 2 — 8 to 24 cal/cm²
- CAT 3 — 25 to 40 cal/cm²
- CAT 4 — 40+ cal/cm²
How to pick the right one
Your arc-rated garment should match the incident energy level at the work task. Not "more protection than I need" — the right amount for the task. The hierarchy is:
- Calculate the incident energy at the task (an engineering study or a published table from IEEE 1584).
- Pick a garment with an ATPV greater than or equal to that energy level.
- Stop there. CAT 4 in a CAT 2 work task is heavier, hotter, and harder to wear — and it does not add safety beyond the threshold.
Why CAT 2 dominates industrial workwear
Most routine industrial work around energized equipment — panel operation, MCC room work, transformer areas — falls in the 8–24 cal/cm² range. That is the CAT 2 bracket, and it is what the overwhelming majority of dual-rated Summit garments are built to.
CAT 3 and CAT 4 garments show up in utility transmission and distribution work, substation switching, and high-energy industrial tasks. Those are specialized roles — not blanket specifications for general crews.
The cost of overspec
Buy CAT 4 for a CAT 2 task and you pay more upfront, your crew carries more weight, summer heat gets worse, and compliance drops because people do not want to wear the gear. The result is often less safety in practice. The right spec is the one your team will actually wear every shift.
If you are uncertain about the right arc rating for your operation, our team will run the spec review with you by task and by job classification. It is part of how we set up corporate programs.
