The evaluation and the analysis of the lightning electromagnetic pulse (LEMP) response of distribution networks require the availability of accurate models of LEMP-illuminated lines and their implementation into software tools able to calculate lightning-induced electromagnetic transients in distribution systems having complex configuration. This paper deals indeed with a computer code, LIOV (lightning induced overvoltage code), and with two interfaces recently realized between it and (a) the DCG/EPRI EMTP96 on the one hand and (b) the SimPowerSystems program in the Matlab-Simulink environment on the other hand. The aim of these interfaces is to extend the simulation capabilities of the LIOV code, which computes lightning-induced voltages on a single multiconductor transmission line above lossy ground, to the case of distribution systems characterized by complex yet realistic configurations. Models/code validation by means of a comparison with experimental results is also presented