ESD - Shoes

What is ESD?

ESD (= electrostatic discharge) - electrically sensitive areas EGB ( = electrostatically endangered construction elements) anti-static. We are all familiar with ESD. It is a spark which jumps from one charged surface to another conductive surface. Whenever we shake another person's hand, this type of discharge occurs.

How do we get charged?

From walking on a carpet, for instance (friction). One of the surfaces (the sole of the shoe) picks up electrons from the other surface (carpet) and, in doing so, becomes negatively charged. The other surface remains positively charged. On non-conductive materials, such as all plastics, for instance, the charges do not move. As they are unable to flow, they are called "static charges". Due to its layer of sweat, human skin is one of the best conductors we know. It is quickly able to pick up a static charge, store it and then release it in the form of a dangerous spark discharge.

Which damage can be caused by ESD?

It is estimated that great damage is caused by ESD, particularly in the field of microelectronics. Semi-conductors and printed circuit boards, which have been rendered defective as a result of exposure to ESD, are fitted into computers, telephone sets or medical equipment. This causes downtime and repair delays with total worldwide costs estimated to amount to billions of dollars every year. Static discharges (spark generation) can also cause explosions, in the varnish industry for instance.


What role can "anti-static shoes" play?

In addition to many other important safety requirements, anti-static shoes or ESD shoes can play an important part in keeping static electricity in check. They help to prevent the wearer from becoming statically charged.


When can a shoe be termed "antistatic"?

A shoe can be termed as being antistatic when its electrical resistance is measured between 10⁵ ohm (100 kohm) and 10⁹ ohm (1000 Mohm).

This is according to the EN 344-1 to EN 347-1/EN ISO 20344-20347 (European standards for Safety, Protective and Professional Footwear).

How can this be measured or, in other words, to which tests are the shoes subjected?

The DIN EN 344-1/EN ISO 20344 standard describes exactly and determinates the required electrical conducting-state resistance. The shoe's rating is measured in unworn status. The shoe must comply with the requirements under the following circumstances:

When performing the tests a level of 10⁵ ohms may not be undercut, and may the level of 10⁹ ohms not be exceeded.

Which factors can influence the values?

The flooring should be of a type which does not nullify the protective function of the shoe. The anti-static rating of the shoe can be considerably influenced by the following factors, in particular:

The wearer or person responsible is recommended to perform regular local examination of the electrical resistance, as and when required.
"Suitable" test stations for shoes are available from specialist stockists.

When can a shoe be termed ESD?

A shoe can be termed ESD when its electrical resistance, according to the standards 61340-5-1 (measurement of the shoe on a metallic plate) is between 5,0 x 10⁴ Ohm and 1,0 x 10⁸ Ohm.

If the shoes have been measured according to the standards requirement the electrical resistance of the system Footwear/ground should be between 7,5 x 10⁵ ohms and 3,5 x 10⁷ ohms.

Consequently this would be an outstanding shoe offered.

How can ESD shoes be identified ?

The ESD symbol is located in a visible position on the outside of the shoe to facilitate identification of ESD shoes.

Where can shoes be subjected to official inspection?

Important:

The subject of "anti-static shoes" and/or shoes for "ESD areas" is of course much wider and more comprehensive than we have been able to cover here. In the event of you having any questions on this subject, we would be only to pleased to answer them.