Protection explained
Know
your kit.
What each hazard does, what the numbers on your label mean, and how to wear multi-norm kit so it works. Plain English, from people who've worn it.
01 · Arc flash
Arc flash.
An arc flash happens when electrical current leaves its path and jumps through the air, between conductors or to earth. In a fraction of a second it releases intense heat and light, a pressure wave and molten metal.
What happens
For a fraction of a second the arc can be hotter than the surface of the sun. The heat travels outwards as radiation and hot gas, with a blast of pressure, noise and light, and molten metal from the equipment itself.
It can happen in switchgear, cable joints, substations, battery systems and distribution boards, often during switching or testing, or when a tool slips.
Why clothing matters
Many of the worst arc injuries come from ordinary clothing catching fire or melting, and carrying on burning against the skin after the flash itself is over. Arc-rated clothing is tested to block a set amount of heat energy, and to stop burning instead of feeding the fire.
Arc-rated garments are rated two ways. The open-arc test gives numbers (ELIM and ATPV). The box test gives a class (APC 1 or APC 2).
The numbers on the label
- ELIM
- Incident energy limitThe highest energy the fabric is tested to take with no predicted burn and no break-open. The cautious figure, and the one to specify against.
- ATPV
- Arc thermal performance valueThe energy at which there is a 50% chance of the heat passing through causing a second-degree burn.
- EBT
- Energy break-open thresholdThe energy at which the fabric breaks open. Where a fabric breaks open before reaching its ATPV, it is rated by EBT instead.
- APC
- Arc protection classThe box test result. Class 1 is tested with a 4 kA arc, Class 2 with a 7 kA arc. Pass or fail.
All energies are in cal/cm² (calories per square centimetre).
Try it · 1/4 Zip fabric test data
Two arc-rated layers worn together can protect more than either alone, but you can't add their numbers. A layered system has to be tested as a system. And never put a meltable layer underneath: a standard polyester base layer can melt onto skin even under an arc-rated jacket.
03 · Anti-static
Static.
Static builds up on clothing as you move. In a flammable atmosphere (gas, fuel vapour, some dusts) a single spark can ignite it. EN 1149-5 clothing lets that charge drain away safely, but only when it's worn the right way.
Every fabric in the range carries a carbon anti-static fibre, so whichever combination is worn, the outer layer dissipates.
-
01
Wear it fastened.
Keep it closed so it covers what's underneath, including zips and other conductive parts.
-
02
Make it the outer layer.
Anti-static clothing has to cover any layer that isn't anti-static. Don't wear a non-AS layer over the top.
-
03
Earth yourself.
Wear dissipative or conductive footwear so the charge has somewhere to go. Without it, the garment can't do its job.
-
04
Don't strip in the zone.
Never open or take off anti-static clothing in a flammable or explosive atmosphere, or while handling flammable substances.
-
05
Keep it clean.
Wash it as the care label says. Contamination and the wrong treatment can affect how it performs.
-
06
Know the limits.
EN 1149-5 isn't designed for oxygen-enriched atmospheres. Check with your safety team before working in one.
02 · Flame & heat
Flame
& heat.
Flame-resistant clothing protects against a brief flash fire, a moment's contact with flame, and heat, then stops burning when the source is gone. It isn't fireproof, and it isn't firefighting kit.
Inherent or treated?
Inherent FR fibres are flame resistant because of what they're made of. Treated fabrics get their resistance from a chemical finish. Both can meet the standard, but with a finish, how the garment is washed matters more.
In S.HENRY fabrics, flame resistance is built into the fibres. It doesn't wash out.
Limited flame spread
EN ISO 14116 is a lighter standard for limited flame spread, rated Index 1 to 3. Index 1 materials must not be worn against the skin. Index 2 and 3 can be.
Every part counts
A flame-resistant fabric sewn with ordinary thread, or closed with a plastic zip, has a weak point. Thread, zips, hook & loop and labels need to be flame resistant too. In the S.HENRY range, they are.
Decode the label
EN ISO 11612, letter by letter
A garment certified to EN ISO 11612 lists the tests it passed as letters, most with a level. It must pass A1 or A2, plus at least one other. Tap a letter.
Under or over FR kit, avoid standard polyester, nylon and acrylic. In a flash fire they can melt onto skin. Base layers should be flame resistant.
04 · High visibility
Be seen.
Hi-vis works two ways. Fluorescent colour stands out in daylight and at dusk. Retroreflective tape bounces headlights straight back to the driver in the dark. You need both, in the right amounts, in the right places.
EN ISO 20471
Three classes
Minimum areas under EN ISO 20471. Garments can be certified as an ensemble: a jacket and trousers worn together can reach a higher class than either alone. Diagram is illustrative.
On the GB mainline railway, the industry standard RIS-3279-TOM calls for orange hi-vis, at least Class 2. S.HENRY's orange fabric is certified to it.
Faded colour, dirt and cracked or worn tape all cut visibility. Wash hi-vis as the label says, and replace it when it no longer looks bright.
Read the sleeve
Four icons.
Four protections.
The S.HENRY badge puts the four protections on the sleeve, so anyone can check a team's kit at a glance. Tap an icon.
05 · Wear it right
Wear it
right.
Multi-norm kit protects you as a system. These habits keep it that way.
-
01
Fasten up.
Zips closed, storm flaps down, cuffs done up. An open jacket leaves skin and non-FR layers exposed.
-
02
Sleeves down.
Arc and flame protection only covers what it covers. Rolled-up sleeves are bare arms.
-
03
FR all the way down.
Avoid meltable base layers like standard polyester or nylon. In a flash they can melt into skin under an FR outer.
-
04
Keep it clean.
Oil, grease and fuel soaked into fabric can burn. Wash as the care label says, and keep hi-vis bright.
-
05
Check it first.
Holes, burns, worn seams, cracked tape or faded colour mean it's time for a repair or a replacement.
-
06
Right size, right layers.
Too tight restricts movement. Too loose snags. Size up if you wear layers underneath or a harness over the top.
Sources
Where the
facts come from.
This page is general guidance. Your employer's risk assessment decides the protection your task needs.
- HSE: Electrical safety at work
- HSE: Work-related fatal injuries in Great Britain (provisional 2025/26)
- Personal Protective Equipment at Work Regulations 1992, regulation 4
- RSSB: RIS-3279-TOM High Visibility Clothing, Issue 2
- Centexbel: High-visibility clothing according to EN ISO 20471
- IEC 61482-1-1 and IEC 61482-1-2: protective clothing against the thermal hazards of an electric arc
- EN ISO 11612, EN ISO 14116 and EN 1149-5: flame, limited flame spread and electrostatic protective clothing
Questions about your spec?
Talk to someone
who's worn it.
Tell us the task and the hazards, and we'll show you how the S.HENRY system covers them.