Don't Forget to Check Your Jacket: Keep the Metal Fittings Covered!

Standard EN 1149-5

EN 1149 is a set of standards for antistatic clothing, requiring garments to effectively dissipate or shield static electricity in hazardous environments (such as explosive atmospheres, electrical work, etc.) to prevent electrostatic discharge sparks from causing accidents.

It explicitly states that metal fittings (e.g., metal zippers, metal buttons, metal rivets) must not be exposed on the outside.

Exposed metal fittings lead to static-related issues

Metal is a good conductor. It can easily accumulate static electricity and rapidly release charges. If the human body or clothing builds up static electricity, metal components—acting as sharp or protruding conductors—can create localized high electric fields, concentrating static charge on their exposed edges or tips.

When brought close to other objects (such as the ground, equipment, or another person), the metal may suddenly discharge (Electrostatic Discharge, or ESD). This discharge can produce tiny but high-energy sparks or arcs.

In environments containing flammable gases, vapors, or dust (e.g., power plants, oil depots,

or near high-voltage equipment), such sparks can ignite combustibles, leading to fires or explosions.

Under EN 1149-5 Requirements

Exposed metal fittings can easily lead to localized static accumulation and sudden discharge, generating sparks and increasing the risk of explosions, fires, or electrical system failures. Therefore, they must be insulated or replaced with non-metallic materials to ensure electrostatic safety.

Item	Exposed Metal Fittings	Non-Exposed Metal Fittings
Static Accumulation	Prone to localized high electric fields	Static distributes evenly, lower risk
Discharge Risk	High risk of sudden discharge (sparks)	Gradual static dissipation, minimal spark risk
Human Safety	Risk of electric shock or burns	Higher safety level
Protective Measures	Requires additional insulation/covering	Inherently safe design, no extra measures needed

Why Does Metal Accumulate Static Easily?

Metal contains a large number of free electrons (mobile electrons) that are not bound to any specific atom but instead float freely like an "electron sea" within the metal. Think of metal as a pool of flowing water—when an external "wind" (electric field) blows, the water piles up at the edges (electrons accumulate on the surface).

Free electrons not only gather easily on the surface but, due to high conductivity, can also transfer rapidly when a potential difference arises, leading to sudden discharge.

In short: Because metal has abundant free electrons, it responds quickly to external electric fields, causing electron buildup on the surface. Combined with its high conductivity, any potential difference triggers instantaneous charge release, resulting in electrostatic discharge (sparks).