To dissipate means to scatter or disperse. In our context, dissipative is an electrical property of the materials we use in Ex luminaires. This property is commonly called ‘anti-static,’ but we prefer to not use that term, because, technically, conductive (see Conductive) materials are also anti-static.
Put simply, at Atexor, we design products and solutions that allow an electric charge (like static build-up) to flow back to earth in a controlled, safe manner. The last thing you want is a spark from a sudden electrical discharge when you are working in an Ex area. A static charge is like a bucket of water. Dump it out all at once and you’ll likely get yourself wet in the process. Pour it slowly, and you stay dry.
For exposed metallic components, it is critical to test the potential for static charge buildup (as well as sparking, but that is a material composition issue).
However, this is equally true for non-metallic parts. Non-metallic does not equal non-dissipative. You need to test the surface resistance of the material to ensure it is actually safe. According to IEC 60079-0, if the resistance is below 1 Gohm (109 ohms) in specified conditions (moisture, etc.), the material is free of static charge risk.