Progress on the development of a measuring instrumentation for detection of pre-discharges on a lightning rod under the influence of a negative downward leader

Since its introduction in 1754 lightning protection has changed only a little. Under the influence of a negative downward leader pre-discharges develop on the tip of a lightning rod, and as a result an upward moving connecting leader is incepted. This leader may reach the downward leader and in consequence defines the point of strike of the lightning. To investigate the complex mechanisms, which comply with the inception of a successful connecting leader, laboratory tests, for example by the Renardières-group, were conducted. It came to light that small pre-discharges would be responsible for the inception of real connecting leaders. This has led to new Lightning Protection Systems (LPS) concepts, which are claimed to have increased impact efficiencies. International standards (such as IEC 62305) describe the application of an effective LPS explicitly by avoiding these new concepts. Theoretical calculations and simulations in the laboratory have proven and disproven these new concepts. This contribution describes the progress and the assumptions of a measuring concept, which will be capable to measure pre-discharges on veritable lightning rods under the influence of natural lightning leaders, as well as the first return stroke. The intention is to learn more about the process how pre-discharges are generated under the influence of lightning leaders.