Antistatic cleanroom garments are often described as compliant with "EN 1149" or "S20.20" as if the two were interchangeable. They are not. They answer different questions, use different tests and protect different things.
The one line answer
- EN 1149-5European standard for protective clothing with electrostatic properties, used where a spark could ignite a flammable atmosphere. The fabric must meet a surface resistance or charge decay requirement. is a European standard for protective clothing that stops the wearer from causing an incendive spark. It matters where there are flammable solvents, vapours or dusts, such as API plants and solvent handling areas.
- ANSI/ESD S20.20A standard for electrostatic discharge control programmes that protect electronic parts. It sets limits for wrist straps, flooring, work surfaces and static control garments. is a standard for an electrostatic discharge control programme that protects electronic parts. Garments are one element of that programme. It matters in electronics, semiconductor and some medical device assembly.
EN 1149-5: material and design requirements
EN 1149-5:2018 sets requirements for the fabric and for how the garment is made. The fabric must pass at least one of these:
- Surface resistanceThe electrical resistance measured across the surface of a fabric, in ohms. Lower values mean charge spreads and dissipates more easily. of no more than 2.5 × 10⁹ Ω on at least one surface, tested to EN 1149-1, or
- Charge decayHow quickly static charge drains from a fabric, measured in seconds. Shorter is better. EN 1149-3 is one test method. tested to EN 1149-3, with a half decay time below 4 seconds or a shielding factor above 0.2.
The design must cover the wearer's own clothing during normal use, and the garment only works when the wearer is earthed, usually through dissipative footwear and flooring. Conductive parts should not be exposed on the outside.
ANSI/ESD S20.20: part of a control programme
S20.20 is about protecting items that are damaged by electrostatic discharge. It sets limits for every element of an ESDElectrostatic discharge: a sudden release of static electricity that can damage electronic parts or ignite flammable vapours. protected area, including wrist straps, flooring, work surfaces and garments. For static control garments it uses resistance tests from ANSI/ESD STM2.1, for example a sleeve to sleeve resistance limit, and stricter limits for garments that are used as part of the grounding path.
A garment can be supplied as suitable for S20.20 programmes, but compliance belongs to the site's programme as a whole.
Which one does your site need?
| Situation | Standard to ask for |
|---|---|
| Solvents or flammable powders, ATEX zoned areas | EN 1149-5 |
| Electronics or semiconductor assembly, ESD sensitive parts | ANSI/ESD S20.20 (or IECImporter Exporter Code: the 10-digit registration every Indian business needs to export goods. 61340-5-1) |
| Sterile pharma with no flammable atmosphere | Antistatic fabric is still useful to reduce particle attraction; ask for the fabric test data |
| Both risks on the same site | Ask for test data against both |
What to ask your supplier
- Which standard the fabric was tested to, by which laboratory and when.
- The measured values, not just a pass or fail.
- Whether the values were measured on new fabric or after a stated number of wash and autoclave cycles.
- Whether conductive yarn is a grid or a stripe and its spacing.
Our garments use carbon grid or stripe polyester. The fabric test report is part of the technical pack, and our team can tell you which values apply to the garment you are considering.
Related reading
Frequently asked questions
Is EN 1149-5 the same as ESD protection for electronics?
No. EN 1149-5 is a protective clothing standard that prevents the wearer from causing an incendive discharge in an explosive atmosphere. ESD protection for electronic parts is covered by ANSI/ESD S20.20 and IEC 61340-5-1.
What surface resistance does EN 1149-5 require?
When the surface resistance route is used, at least one surface must measure no more than 2.5 × 10⁹ Ω when tested to EN 1149-1. The alternative route uses charge decay to EN 1149-3: half decay time below 4 seconds or a shielding factor above 0.2.
Do antistatic garments work if the wearer is not earthed?
Not reliably. EN 1149-5 garments rely on the wearer being earthed, normally through dissipative footwear and flooring, so that charge can drain away.