The least time/maximum probability theories of lightning propagation and lightning protection

The least time-maximum probability (LT-MP) principle is the basis for a statistical theory of lightning propagation. The theory explains why lightning travels in a tortuous path, how branching occurs, why all channels are not equally bright, and most importantly, where lightning may strike next. The least time-maximum probability principle is a rule for selecting lightning channels. Without such a selection rule, there cannot be a theory of lightning protection. In Paper #27-TC8-4, the authors essentially recommended withdrawal of NFPA 780-1997 (as written) because it does not have the technical or scientific basis for a Standard, and because in some applications, the recommended lightning protection systems in the Standard are dangerous. They recommend that the least time-maximum probability theory be considered as a candidate for the scientific basis for an industrywide Standard for lightning protection systems.