How do you know static electricity is present?

Answer 1

An electrostatic meter reads static electricity without contact - and is safer to use if very high voltage of static build-up is likely to be present. Under more normal examples of static build-up (in your body, or conductive surface, nylon carpet, etc.) a spark will jump between your finger and the conductive material. As a static spark could cause a fire (in a corn mill, and in sensitive production processes, etc.) all the equipment will be earthed.