Antistatic footwear should be used when electrostatic charges need to be dissipated to stop them from building up – in order to prevent the risk of fire breaking out due for example to flammable substances and fumes – and where the risk of electric shock from electrical equipment or other live elements has not been completely eliminated. It should however be noted that antistatic footwear cannot guarantee adequate protection against electric shock by merely introducing an electrical resistance between the foot and the ground. If the risk of electric shock has not been completely eliminated, additional measures will also be necessary. These measures, as well as the additional tests listed below, should be part of periodic checks on the procedures for preventing accidents in the workplace.
Experience has shown that for antistatic purposes the discharge path through a product must have, under normal conditions, an electrical resistance of less than 1000 MΩ at any time during the life of a product. A value of 100 KΩ is set as the product lower resistance limit when brand new, in order to ensure a certain degree of protection
against dangerous electric shock or against fire in the event of defects in electrical equipment working at voltages of up to 250V. However, users should be informed that under certain conditions the protection given by the footwear may be ineffective and so other methods should be used to protect the wearer at any time. The electrical resistance of this type of footwear may change considerably by flexing, contamination or humidity. This type of footwear will not serve its intended purpose if worn and used under damp conditions. Consequently, it must be ensured that the product is able to carry out its function of dissipating electrostatic charges and to provide a certain degree of protection during its entire lifetime. The user is advised to carry out an electrical resistance test on site and to use it at frequent and regular intervals. Class I footwear may absorb humidity if worn for long periods; in such cases, as well as in wet conditions, it may become conductive.
If the footwear is used under such conditions that the material used for the sole becomes contaminated, wearers must always check the electrical properties of the footwear before entering a risk area.
While wearing antistatic footwear, it must be ensured the sole resistance does not cancel out the protection provided by the footwear.
While in use, no insulating element must be introduced between the outsole of the footwear and the wearer’s foot. If an insole is introduced between the sole and the foot, the electrical properties of the footwear/insole combination must be checked.