Distribution of Currents in the Lightning Protective System of a Residential Building—Part II: Numerical Modeling

The distribution of lightning current in the lightning protective system (LPS) of a test residential building was experimentally studied in 2004 and 2005 at Camp Blanding, FL. Lightning was initiated using a rocket-and-wire technique and its current was injected into the LPS. Results are presented in the companion paper. The current distribution is modeled here using a model based on the lumped circuit theory in the frequency domain. The injected lightning current is represented in the model by an ideal current source. The effect of electromagnetic field radiated by the lightning channel is also accounted in the model (for one of the configurations tested). In field calculations, the lightning channel and the wire connecting the rocket launcher and the test house are modeled as vertical and horizontal electric dipoles above lossy ground. The discrete complex images method is used to calculate the electromagnetic field radiated by the electric dipoles. The time-domain current waveforms are obtained by means of the inverse Fourier transform. The calculated currents in the LPS are compared with those measured.