Buying guide
Choosing safety eyewear: EN 166 markings explained
How do I choose safety glasses or goggles using the EN 166 markings?
The short answer
EN 166 is the general standard for eye protection. The markings on the frame and lens tell you the impact level, which hazards the product is intended for and some lens properties. The mechanical strength letters run from S for increased robustness up to A for the highest impact test, and the digits for the field of use include 3 for liquid droplets and splashes, 4 for large dust particles and 5 for gas and fine dust. Match the markings to the hazards in your own risk assessment, and choose goggles rather than spectacles where splashes or fine dust are the concern.
Where the markings are
Safety eyewear carries markings on the lens and on the frame. A typical frame might read something like 166 F, meaning it meets EN 166 and passed the low energy impact test, and a lens might carry a code such as 2C-1.2 for its filter and then 1 F for its optical class and impact level. A lens and a frame can carry different marks, and the lower of the two sets the rating for the product as a whole.
| Mark | Test | What it represents |
|---|---|---|
| S | Increased robustness | A steel ball dropped from a set height, a basic strength test |
| F | Low energy impact | A small steel ball fired at 45 metres per second |
| B | Medium energy impact | The same ball at 120 metres per second |
| A | High energy impact | The same ball at 190 metres per second |
Field of use digits
| Digit | Intended for |
|---|---|
| 3 | Liquid droplets and splashes |
| 4 | Large dust particles |
| 5 | Gas and fine dust particles |
| 8 | Short circuit electric arc |
| 9 | Molten metal and hot solids |
- K on a lens means it resists surface damage from fine particles, which helps it keep its clarity.
- N on a lens means it resists fogging, which is useful in warm or humid work.
- Optical class 1 is the highest and is intended for continuous wear. Classes 2 and 3 are for short or occasional use.
- A T after the impact letter means the impact rating also applies at extreme temperatures. Without it, the rating is for normal conditions.
Goggles seal where spectacles do not
Spectacles leave gaps at the sides and above. Where the hazard is a splash, fine dust or something that can arrive from the side, goggles that seal to the face and carry the right field of use digit are usually the better fit.
Safety spectacles
Safety spectacles from the catalogue. The markings each manufacturer states are on the product page.
Safety Spectacles · PW32
Wrap Around Safety Glasses
Despatched within 1-2 working days
Safety Spectacles · PW30
Visitor Safety Glasses
Despatched within 1-2 working days
Safety Spectacles · PW34
Profile Safety Glasses
Despatched within 1-2 working days
Safety Spectacles · PS12
Tech Look Safety Glasses
Despatched within 1-2 working days
Check against your own risk assessment
Markings describe how a product was tested. Your risk assessment decides what hazards are present and what rating you need. Prescription eyewear, welding and laser work have their own requirements and are outside this guide.
Common questions
Are safety glasses and goggles interchangeable?
Not always. Spectacles suit impact from the front where there is no splash or fine dust risk. Goggles seal to the face and are intended for splash, dust and gas hazards, where their field of use digit says so.
Do I need B or A impact protection?
Only if your risk assessment says so. Higher impact levels are for tasks with fast particles, such as grinding or cutting, and are usually specified by the site or the task.
Can I wear safety glasses over my own glasses?
Over-spectacles are designed for this, and many people use them. Check that they fit without pressing on your own frames and that the markings meet your risk assessment.
Keep reading
Still not sure what you need?
Check the standard against your own risk assessment, and if you are still not sure, call us and talk it through with someone who knows the catalogue.