Static electricity: source of fire and explosion

Static electricity is an everyday phenomenon. Who hasn't felt a small electric shock when approaching a vehicle, touching an office door handle, or shaking hands with a colleague? The phenomenon is so familiar that everyone lives with it. However, this harmless incident can have far more serious consequences, including death and material damage to the production plant. This source of ignition is often suspected when investigating the causes of incidents and accidents, but manufacturers find it difficult to analyze and objectify its sudden appearance.

Static electricity remains the most complex risk to assess and prevent, both when it is taken into account by manufacturers of materials and equipment, and when it occurs in production and plant use. Compared to other sources of ignition, the greatest difficulty lies in the fact that it encompasses the human environment at the workstation. Indeed, in addition to the machine, the operator is a known and understood source of electrostatic accidents. It should be remembered that it is only since July 1 ^er 2003 that regulations have been reinforced, with Article R. 4227-46 of the French Labour Code clearly requiring this source to be taken into consideration: "the assessment of explosion risks must take into account the probability that ignition sources, including electrostatic discharges, will be present and become active and effective".

It is therefore important to shed some light on these specific concepts, which are the starting point for the application of these regulations and the implementation of an effective global assessment approach to this electrostatic phenomenon.

Manufacturers are made aware of prevention rules for dealing with and limiting the development of electrostatic charges on materials. Significant progress has been made by manufacturers in their choice of equipment and materials, and in implementing control and maintenance procedures to limit electrostatic risks. However, the operator working on these installations is exposed to a significant and recurring electrostatic risk. In this article, we focus on the risk to the operator. It recalls the rules of prevention, focusing first and foremost on personal protective equipment.