Shoes are classed as ESD shoes when the on-state resistance value of the system person-shoe-floor is below 3,5 x 10⁷ resp. 35 MOhm according to EN 61340-5-1 (verification).
The qualification of the shoes is made depending on the climate classifications 1 (15% relative humidity), 2 (25% relative humidi- ty) and 3 (50% relative humidity) according to EN 61340-4-3 < 10⁸ Ohm.
Attention should be paid to the different procedures of both of the test methods: EN 61340-4-3 metal balls in the shoe on a metal plate; EN 61340-5-1 human being in the shoes on a metal plate or the floor used.

Shoes used for primary grounding in ESD protection must be selected in combination with the floor covering to be used so that the combined resistance to ground (Rg) is in the range required. (Please, refer to the information leaflet in the carton.)

• Climatic conditions (humidity, temperature)
• Soiling of the floor 
• Speed of separation of parts 
• Nature of material
• Nature of the surface 
• Electrical resistance of the surface 
• Material and construction of the shoe
  
  

The above mentioned influences are affecting more or less the ESD properties of ESD shoes. The level of charge generated is highly influenced by atmospheric humidity (% RH) and temperture.

According to the ESD DIN EN 61340 standards, the ESD coordinator in the company must take into account both best and worse climatic conditions, for instance minimum temperature with minimum relative humidity or maximum termperature with maximum relative humidity, in order to test if the parameters of ESD protection are continuously in line with the standards.

When setting up an "EPA area", the following question should always be asked:

How many volts can the device withstand?

Because it requires only approximately:

• 3000 Volt, to let a person have a disagreeable sensation
•   100 Volt, to delete information from a magnetic data medium
•     50 Volt, to generate sparks which can inflame explosive gases
•     30 Volt, to damage electrical components
•       5 Volt, to damage highly sensitive hard-disc reading heads during production.

In many cases discharges cause "latent damage" that manifest as defect or trouble only after a certain period of time or under specific circumstances.

For the daily function testing of the shoes, the use of test stations has been established. There the resistance of person and shoe is measured. Attention should be paid to the separate measuring to the feet. 

ESD

Electrostatic Discharge
Electrostatic Discharge caused by an imbalance of potential on charged objects or persons by contact or close proximity. 

EDSD

Electrostatic Discharge Sensitive Device 

EPA

Electrostatic Protected Area
Area equipped with ESD protective measures.

Electrostatic Charge

Is produced by frictional contact and seperation of materials 

Resistance to the ground (Rg) according to EN 61340

Is the resistance between an electrode on the surface and the grounding point. 

Latent damages

Is the damage cause by the ESD effect to sensitive devices which is reducing the the components reliability without causing immediate failure