ESD

Specific articles for the protection of

electrostatic phenomena

ESD

What is it?

ESD (Electro Static Discharge)

Electrostatic Discharge, a phenomenon that we all know, but which assumes a high importance for work footwear, is caused by a difference of potential expressed in volts.

Specifically, a differential of 3000 volts represents the threshold for human perception.

Much lower values, such as 30 volts, are sufficient to damage a semiconductor (e.g. microchip).

When a person is isolated from the ground, for example wearing rubber shoes, he is charged with static electricity quickly reaching the above values.

ESD

How does it work?

Materials for work footwear with antistatic or conductive properties are in compliance with EN ISO 20344 standard.

The ability to dissipate static electricity is measured through a test indicating the "resistance" that a material opposes to the passage of electrons.

The value is expressed in Ohms.

In ascending order we pass from conductive to antistatic and finally to insulating.

ESD

When a material is ESD classified

The table highlights the ESD area.

In short, a material is antistatic for values between 10⁵ and 10⁹ Ohm and is conductive between 10² and 10⁵ Ohm.

However, this is not enough to classify a material as ESD.

The value must be obtained in an environment with Relative Humidity not exceeding 12%, as humidity plays an important role: if high, it acts as a dissipative agent.

Generally, items treated with antistatic agents need high ambient humidity to dissipate the electrostatic charge.

Items with intrinsically conductive components dissipate even in dry environments.

ESD

Footwear classification

For ESD footwear, the reference standard is CEI EN 61340-5-1, protection against electrostatic phenomena.

It provides the technical and organizational requirements necessary for the preparation, implementation and maintenance of an electrostatic discharge protection program resulting as a practical guide for its realization.

The requirement for testing on unworn footwear, according to the methodology of the CEI EN 61340-4-3:2002 standard, has been unified: R ≤1x10⁸ Ω.

The conditioning for the above test has been unified at 23±2 °C e 12±3 % of relative humidity.

Electrical resistance requirement of the user/footwear/floor system: Rg <1x10⁹ Ω.

The body voltage measurement test has also been introduced, which must be <100 V, always carried out after conditioning at 23±2°C and 12±3% of R.H.