This technical report provides elements for: the design of an adequate protection for civil facilities against the electromagnetic pulse due to a high altitude nuclear explosion, denoted in what follows by HEMP; the evaluation of already existing protections with respect to stresses imposed by HEMP; to compare the requirements of HEMP and lightning protection in order to show if they can be combined at low cost; to emphasise the differences between the requirements of HEMP and lightning protections in order to permit the evaluation of the consequences of HEMP when no additional measures are taken except existing lightning protection.