The widespread use of sensitive electronic devices has increased the interest on transients, in particular those caused by lightning (direct and/or indirect). This tutorial presents the latest developments in modelling the electromagnetic (indirect) effects of lightning. The progress in field-to-transmission lines coupling calculations for networks permits the analysis of more complicated structures submitted to a lightning electromagnetic field. Combined approaches using low frequency coupling expressions which neglect the propagation in the case of complicated circuits but with small dimensions are discussed. Such approaches can give approximative solutions and orders of magnitude helpful for a correct EMC design for very complex configurations like for instance control and protection circuits in power network substations