BS EN 12600 is the pendulum impact test that classifies flat glass by how it behaves when a person-sized soft body hits it. A result such as 1B1 tells you the impact height survived and the way the glass broke. It does not tell you whether a particular door, display or enclosure is fit for purpose. This guide explains how to read the classes, where IK ratings fit, and what a procurement or engineering team should ask a glass supplier to prove.
TL;DR
- BS EN 12600:2002 is the British Standard for the pendulum impact test on single flat panes of glass used in buildings. It classifies glass by impact level and breakage mode.
- The three classes are 3B3 (190 mm drop), 2B2 (450 mm) and 1B1 (1,200 mm). 1B1 is the highest.
- IK ratings (IK00 to IK10) come from a different standard, IEC 62262, and cover enclosures for electrical equipment. IK10 is not the same thing as 1B1.
- A class belongs to the tested specimen. Thickness, interlayer, size, edge condition, coating and fixing all matter, so ask for a report tied to your actual construction.
- For defence, blast, fire or ballistic work, EN 12600 is one input among several, never the whole qualification.
Table of Contents
- What BS EN 12600 actually tests
- Reading 1B1, 2B2 and 3B3
- Where it applies in UK building work
- IK ratings are a different question
- When EN 12600 is not enough
- Our perspective: evidence tied to the part you will receive
- A specification checklist for custom glass
- Common mistakes we see in impact specifications
- Custom glass for impact-critical applications
- FAQ
- Sources
What BS EN 12600 actually tests
The standard specifies a pendulum impact method for single flat panes. The aim is to sort flat glass products into three principal classes, according to performance under impact and mode of break. It is maintained by BSI committee B/520.
The purpose is personal safety. The classification addresses the risk of cutting and piercing injuries and describes how the broken pane holds together. It does not say where a pane must be used, and it does not specify durability. ISO 29584, the international pendulum standard, draws the same boundary: the result communicates impact performance and breakage behaviour, not intended use.
In practice the test works like this:
- A specimen pane is mounted in a prescribed steel frame.
- A twin-tyre pendulum impactor is released from a set drop height.
- The laboratory records whether the pane broke and, if so, how.
- The result is written as a three-part code.
Reading 1B1, 2B2 and 3B3
The code has three positions. The first number is the impact level, the letter is the breakage mode, and the final number repeats the impact level at which the breakage behaviour was achieved. The drop heights are set out in this EN 12600 testing summary.
| Class | Drop height | Typical reading |
|---|---|---|
| 3B3 | 190 mm | Lowest of the three classes |
| 2B2 | 450 mm | Intermediate |
| 1B1 | 1,200 mm | Highest of the three classes |
The letters distinguish how the glass fails. Annealed glass typically breaks into large, sharp shards. Laminated glass cracks but is held together by its interlayer. Toughened glass breaks into small, blunt particles. A pane that survives without breaking at a given height also earns the class for that height. This is why laminated and toughened constructions dominate where safety glazing is called for.
Why a number is not a strength rating
The most common misreading is to treat 1B1 as a general toughness score for a material. It is evidence about a specimen, tested in a prescribed frame, at a defined size and thickness. Published work on numerical simulation of the EN 12600 test shows how much frame interaction, clamping and post-breakage response influence what happens in the test.
The consequence for custom parts is direct. A certificate for one thickness, interlayer, size or edge condition should not be stretched to a materially different component.
Where it applies in UK building work
In building work, EN 12600 sits alongside the Building Regulations for the nation where the project is located. Government guidance on protection against impact says that glazing people are likely to contact while moving around a building should break safely, resist impact, or be shielded. Doors, door side panels and low-level glazing in walls and partitions are the principal risk locations.
Two practical points follow:
- Always check the current edition of the guidance that applies to your jurisdiction. England, Scotland, Wales and Northern Ireland each have their own technical documents.
- The class you need comes from the regulation or the project specification, not from the glass supplier. The supplier’s job is to supply evidence that the product meets it.
You may still see older drawings that cite BS 6206. EN 12600 is the standard that classification is now reported against, so a modern specification should name it.
IK ratings are a different question
Searches for IK ratings often land on the same pages as EN 12600, but the two answer different questions. IEC 62262 defines protection of enclosures against external mechanical impacts on a scale from IK00 to IK10. IK10 corresponds to 20 joules, roughly a 5 kg mass dropped from 400 mm.
| BS EN 12600 | IK rating (IEC 62262) | |
|---|---|---|
| Subject | Flat glass in buildings | Enclosures for electrical equipment |
| Impactor | Soft body, pendulum | Hammer, defined energy |
| Concern | Injury to people, breakage mode | Protection of the enclosure and its contents |
| Scale | 1B1, 2B2, 3B3 | IK00 to IK10 |
For luminaires, displays and instruments, the cover glass often needs both. The UL guidance also points out that an impact-resistant cover does not automatically deliver dust or water protection. Impact (IK), ingress (IP), optical performance and function are separate characteristics, and each needs its own acceptance criterion.
So if a specification says “IK10 glass”, ask which part is being rated. The IK result applies to the tested enclosure, including its mounting, gasket and frame, not to a loose piece of glass.
When EN 12600 is not enough
Impact classification is not a blast, ballistic, forced-entry, fire, pressure, vibration or environmental qualification. Each of those has its own test regime.
Blast is a good example. NPSA guidance on internal glazing subjected to blast states that response depends on glass make-up and support conditions. For the internal-blast case it covers, it recommends laminated glass with PVB or ionomer interlayers and an interlayer of at least 1.52 mm to limit fragmentation hazard. That is conditional guidance for a defined scenario, not a universal rule, and it does not replace a project-specific blast assessment.
The lesson is that what governs the hazard is not only whether glass breaks, but whether fragments stay attached, how heavy the broken sheet becomes and how it is supported. For related topics see our guides on anti-shatter interlayers, ballistic glass and fire glazing for OEMs.
Our perspective: evidence tied to the part you will receive
We manufacture custom technical glass for medical devices, defence, aerospace, automotive dashboards, lighting, electronics and marine applications. Most of what we make is not a plain rectangular pane in a steel test frame. It is CNC-machined, edge-finished, chemically strengthened, coated, ceramic-printed or laminated, and each of those steps can change how a part behaves under impact.
That is why we tell engineering and procurement teams to separate three questions:
- Which standard applies to this product? EN 12600 for glazing in buildings, IK for enclosures, and sector standards for vehicles, marine and defence.
- What construction was actually tested? Thickness, interlayer, size, edge and fixing must match what you will buy, or be covered by a justified qualification plan.
- What else must the part do? Optical clarity, coating durability, ingress protection and thermal limits are specified and verified separately.
Our positioning rests on ISO 9001 certification, batch-level traceability, scalable production from prototype to volume, advanced inspection and documented export compliance. For impact-critical parts, traceability is what makes a test report meaningful: you can link the delivered batch to the construction and process that the evidence describes.
— Alexandra
A specification checklist for custom glass
Use this list when you write an RFQ that mentions impact performance.
- Name the standard and the class. For example, “BS EN 12600 class 1B1” or “IK10 on the assembled enclosure”, not “impact resistant”.
- State the construction. Glass type, thickness, interlayer type and thickness, strengthening method, coatings and printing.
- State dimensions and edge condition. Size and edge finish influence breakage, and custom shapes need justification against the tested specimen.
- Describe the support. Frame material, clamping or bonding method and gasket. In the test, the frame is part of the result.
- Define post-breakage behaviour. Must fragments stay in place, and for how long? Is the part load-bearing?
- List the other requirements. IP, optical transmission, thermal range, vibration, chemical exposure and any blast, ballistic or fire requirement.
- Ask for the evidence. A test report on the same construction, or a technical justification and a plan to test a representative sample.
- Require traceability. Batch records that tie delivered parts to the tested build.
If you are choosing between glass families first, our protective glass types guide for procurement teams and the glass selection tips for industry set out the trade-offs. Coating wear is a separate topic, covered in our note on abrasion testing for glass coatings.
Common mistakes we see in impact specifications
Treating a catalogue class as a guarantee for a custom part. A class quoted for a standard laminate says little about a version with machined slots, a printed border or a different edge.
Asking for “IK10 glass” without defining the assembly. The result depends on the enclosure, mounting and the exact hammer positions.
Mixing up breakage mode and strength. A toughened pane may break more safely than annealed glass, yet that is a statement about fragments, not about resistance to every load.
Skipping the durability question. The standard does not specify durability, so ageing, coating wear and environmental exposure need their own tests. Our guide to optimising glass durability covers this.
Forgetting that regulations vary by location. The same glass may need to meet different documents in England, Scotland, Wales and Northern Ireland.
Custom glass for impact-critical applications
If your project needs toughened, laminated, coated or machined glass with a defined impact requirement, we can review your drawing and specification. Our services cover glass cutting, CNC glass machining, edge finishing, toughened and laminated glass, AR and AG coatings, display glass, optical windows and custom components. For machined parts, see our guide to RFQ-ready CNC glass machining, or review our technical glass range. Send us the standard, the construction and the support conditions, and we will tell you what evidence is needed and what can be delivered.
FAQ
Is BS EN 12600 the same as BS 6206?
No, but they are related. EN 12600 is the pendulum test method and classification now cited for flat glass in buildings, and older documents may still refer to BS 6206. For new specifications, name BS EN 12600 and the class required.
Is IK10 glass the same as 1B1 glass?
No. IK10 is a 20 joule impact rating from IEC 62262 for enclosures, while 1B1 is a 1,200 mm pendulum class for flat glass. A luminaire or display may need both, plus an IP rating, so specify each separately.
Which class is the best?
1B1 is the highest of the three classes, with a 1,200 mm drop height. Higher is not automatically what you need: the class must come from the applicable regulation or your project specification, and the construction must be tested to achieve it.
Does an EN 12600 class cover blast or ballistic requirements?
No. Impact classification is not a blast, ballistic, fire or forced-entry qualification. Blast-sensitive projects should follow specific guidance such as the NPSA documents and a project-specific assessment.
Can a test report for one pane cover a custom machined part?
Not automatically. Results are tied to thickness, interlayer, size, edge condition and fixing. A materially different part needs a technical justification or its own test.
Sources
- BS EN 12600:2002, BSI Standards listing
- BS EN 12600:2002, BSI Knowledge
- ISO 29584:2015, Pendulum impact testing and classification of safety glass
- EN 12600 Safety Glazing Testing Summary
- Numerical simulation of the EN 12600 Pendulum Test for Structural Glass
- UK Government guidance on protection against impact
- NPSA: Internal Building Glazing Subjected to Blast
- UL: IK and IP Testing for Lighting Products
- Lumascape: IK ratings
