IEC 62305-1:2010(E) provides general principles to be followed for protection of structures against lightning, including their installations and contents, as well as persons. This second edition cancels and replaces the first edition, published in 2006, and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: 1) It no longer covers protection of services connected to structures. 2) Isolated interfaces are introduced as protection measures to reduce failure of electric and electronic systems. 3) First negative impulse current is introduced as a new lightning parameter for calculation purposes. 4) Expected surge overcurrents due to lightning flashes have been more accurately specified for low voltage power systems and for telecommunication systems.