Arc 0
Class (Box Test)
Baselayer
ELIM Range (cal/cm²)
0-4
Example Products
ProGARM® 8210 Baselayer Top (3.6 cal/APC 1)
UNDERSTANDING ARC FLASH
ARC Tiers Explained
A practical guide to APC classification, ARC ratings, and how to choose the right level of Arc Flash protection for your team.
THE BASICS
What does an Arc Rating actually mean?
An ARC tier is the rating used to identify the Arc Flash protection a garment provides for a given work task. Some tasks demand higher protection levels, and the right level for your team is determined by your employer’s Arc Flash study or risk assessment.
Faulty electrical equipment, depending on its energy capability, can cause an Arc Flash incident of a certain magnitude, measured in calories per square centimetre (cal/cm²). The resulting incident delivers a quantifiable amount of heat over a defined distance.
Each level of Arc Flash protection is rated to withstand a specific incident energy without the wearer suffering second-degree burns. Choose a level that exceeds the incident energy your team will face.
AT A GLANCE
What about ATPV Testing?
ProGARM aligns to the European IEC 61482-2 standard. Garments are classified as APC 1 or APC 2 (from the Box Test) and given an ARC 1 to ARC 4 rating based on their ELIM cal/cm² value (from the Open Arc Test). Arc 0 products are usually FR and are usually limited to baselayers. They offer low protection but can increase the protection through layering and prevent undergarment ignition.
| Term | Class (Box Test) | ELIM Range (cal/cm²) | Example Products |
|---|---|---|---|
| Arc 0 | Baselayer | 0-4 | ProGARM® 8210 Baselayer Top (3.6 cal/APC 1) |
| ARC 1 | Polo Shirt | 4-8 | |
| ARC 2 | Jacket | 8-25 | |
| ARC 3 | Jackets & Baselayers | 25-40 | |
| ARC 4 | Switching Suits | 40+ |
ARC 1
Class (Box Test)
Polo Shirt
ELIM Range (cal/cm²)
4-8
Example Products
ARC 2
Class (Box Test)
Jacket
ELIM Range (cal/cm²)
8-25
Example Products
ARC 3
Class (Box Test)
Jackets & Baselayers
ELIM Range (cal/cm²)
25-40
Example Products
ARC 4
Class (Box Test)
Switching Suits
ELIM Range (cal/cm²)
40+
Example Products
TEST METHODS
IEC 61482-1-2
European standards specify two distinct test methods for Arc Flash protective clothing. ProGARM garments are tested using both.
THE BOX TEST
IEC 61482-1-2
Open Arc test method (ATPV test and garment test). This replaces IEC 61482-1:2002. The Open Arc test method is the same as the original North American method for measuring the Arc Thermal Performance Value (ATPV), as used in ASTM F1959.
WHERE IT IS USED
- Energy suppliers and grid operators
- Medium and low-voltage plants
- Switchgear construction and maintenance
- Railway technology and municipal utilities
RESULT
Garments are classified as APC 1 or APC 2
THE BOX TEST
IEC 61482-1-1
Assesses performance under an open electrical arc, the type of exposure workers may encounter in real-world industrial environments. Measures Arc Thermal Performance Value (ATPV/ELIM), showing exactly how much energy a fabric or garment can withstand before a burn occurs.
WHAT IT MEASURES
- ELIM
- Limit of Energy. The preferred and most conservative rating.
- ATPV
- Arc Thermal Performance Value. Used where ELIM is not available.
- EBT
- Energy Breakopen Threshold. Used for fabrics that fail by breakopen.
Result
Each results in an Arc 1 - Arc 4 Rating.
ATPV, EBT50, ELIM, Box Test
Understanding arc flash ratings: ATPV, EBT50, ELIM and the Box Test
When you’re choosing arc-rated PPE, you’ll come across several different numbers and abbreviations on a garment’s label or test certificate — ATPV, EBT50, ELIM, APC. They can look interchangeable, but they’re not. Each one comes from a different test method, measures a different kind of failure, and tells you something different about how the garment will behave in a real arc flash event.
ATPV
What is ATPV, and how is it different from other arc ratings?
ATPV (Arc Thermal Performance Value) is the most widely known arc rating, and the one most safety professionals are trained to look for. It comes from the Open Arc test (IEC 61482-1-1 / ASTM F1959), where a mannequin wearing the garment is exposed to a free-burning arc across a range of energy levels. Sensors behind the fabric measure how much heat passes through, and the result is the energy level, in cal/cm², at which there’s a 50% probability of the wearer suffering a second-degree burn.
ATPV is the figure used to build NFPA 70E’s PPE Category system, which is why it’s the benchmark most incident energy calculations are measured against. If a job is calculated at 8 cal/cm², you need a garment with an ATPV rating at or above that figure.
EBT50 vs ATPV
What does EBT50 tell you that ATPV doesn't?
EBT50 (Energy Breakopen Threshold) comes from the exact same Open Arc test as ATPV, but it captures a different way a fabric can fail. Instead of heat gradually transferring through an intact fabric, breakopen means the fabric itself tears or melts through, opening a hole that exposes skin directly to arc plasma and flame.
During testing, a fabric only ever fails one way first — either by heat transfer (reported as ATPV) or by breakopen (reported as EBT50), whichever happens at the lower energy level. A garment quoting EBT50 rather than ATPV is telling you that breakopen, not heat transfer, is its limiting factor — which makes garment construction, seams and closures just as important as the fabric itself. Like ATPV, EBT50 is still a 50% probability figure: at the rated energy, roughly half of identical real-world exposures would result in a burn injury.
ELIM
Why is ELIM considered the strictest, safest rating?
ELIM (Incident Energy Limit) is the newest of the three Open Arc values, added to IEC 61482-1-1 in 2019. Where ATPV and EBT50 both describe a 50/50 chance of failure, ELIM is calculated differently: it’s the highest incident energy at which none of the tested responses crossed the burn threshold — effectively, a 0% probability of injury rather than 50%.
Because it removes the coin-flip built into ATPV and EBT50, ELIM will always be equal to or lower than a garment’s ATPV/EBT50 value. It’s a more conservative, more risk-averse number by design, which is why it’s increasingly treated as the preferred arc rating under EN 61482-2:2020 — some manufacturers now quote ELIM as the primary or only figure on a garment’s label. In short: ATPV and EBT50 tell you the energy at which a garment fails half the time. ELIM tells you the energy at which it doesn’t fail at all.
Box Test vs Open Arc
How is the Box Test different from an Open Arc rating?
The Box Test (IEC 61482-1-2) is a different test altogether, not a different way of scoring the same test. Rather than an open, free-burning arc, it uses a constrained, directed arc inside an open cabinet — closer to what happens if a fault occurs inside switchgear or an enclosed panel, generated by a fixed short-circuit current of either 4kA or 7kA.
There’s no sliding cal/cm² scale here. A garment either passes the exposure or it doesn’t, and the outcome is one of two classes: APC 1 (passes at 4kA / 168 kJ) or APC 2 (passes at 7kA / 320 kJ). The Box Test is faster and cheaper to run, and — because it tests the whole garment rather than just fabric — it also checks build quality: seams, zips, and closures under real arc exposure. That makes it a useful complement to an Open Arc rating rather than a replacement for it.
CHOOSING THE RIGHT LEVEL
How do I know which level my team needs?
The right level of Arc Flash protection is determined by your employer's Arc Flash study or a documented risk assessment of the tasks your team performs. The garment must be rated above the incident energy at the working distance of the task.
If you have not yet completed an Arc Flash study, our specialist team can help you scope one and recommend products that match your environment.
STILL UNSURE?
We can help you get the right protection level for your team.
Other Questions
Frequently Asked Questions
What are arc flash protection levels?
Arc flash protection levels — often labelled ARC 1 to ARC 4 — describe the amount of incident energy, measured in cal/cm², that a garment can withstand before it's likely to cause a second-degree burn. ARC 1 covers the lowest-risk environments (4–8 cal/cm²) and ARC 4 covers the highest (40+ cal/cm²), with each level requiring progressively heavier or multi-layered protective clothing.
How do I know which arc flash protection level I need?
The right level comes from an arc flash risk assessment of your specific equipment and task, which calculates the incident energy a worker could be exposed to in cal/cm². That figure is then matched against a garment's ATPV or ELIM rating — not guessed from job type or industry alone, since the same role can carry very different risk levels depending on the equipment involved.
What happens if I wear PPE rated below the required protection level?
The garment may not fully protect against the incident energy present in a real arc flash event, increasing the risk of second- or third-degree burns. Ratings aren't a safety margin to round down from — PPE should always meet or exceed the calculated incident energy for the task, not simply come close to it.
Can layering clothing increase my arc flash protection level?
Yes — combining garments can raise overall protection above the sum of their individual ratings, because the air gap between layers adds extra insulation. However, the combined rating can't be assumed; it needs to be tested as a full clothing system under IEC 61482-1-1, since fabric type, fit and layer order all affect the result.
Does a higher cal/cm² number always mean a safer garment?
Not automatically, and not across different test methods. A higher ATPV or ELIM value does mean better protection within that same test method, but you can't compare an ATPV figure directly to a Box Test's APC class, or assume a garment is safer just because one of its listed values looks bigger — always compare like-for-like ratings.
Do arc flash protection levels expire, or can ratings change over time?
A garment's tested rating doesn't change on its own, but the actual protection it provides can degrade with wear, washing, damage, or non-FR alterations (like non-rated repairs or added trims). Manufacturers' care instructions exist specifically to preserve the tested rating, and garments should be inspected regularly and replaced if damaged or visibly worn. ProGARM typically last 70% longer when tested against competitor garments, reducing costs in the long term. ProGARM products use inherent fabrics meaning the protection will not wash out like treated garments.
How does ProGARM make it easy to check a garment's protection level in the field?
Every ProGARM garment carries SafetyICON, a visual marker sewn into the garment that shows its protection type and level at a glance — including Arc Flash and Flame Resistance, Anti-Static capability, and the relevant EN standards it meets. Where a garment is certified to more than one standard, SafetyICON displays each one clearly, so workers and supervisors can confirm the right PPE is being worn for the job without needing to interpret a label full of technical codes.
What are ThermSAFE components, and how do they add to a garment's protection?
An arc rating only tells part of the story — zips, poppers, buttons and other trims can be a weak point if they're not flame resistant too. ProGARM's ThermSAFE range covers zippers, poppers, buttons and Velcro, made from military-grade, non-spark FR materials and tested to keep functioning even after an arc flash event, rather than melting, sparking, or failing at the fastenings. Fitting ThermSAFE components as standard means the protection built into the fabric isn't undermined by the hardware holding the garment together. Content