To prepare international standards for surge protective devices (SPDs) for protection against indirect and direct effects of lightning and/or against other transient overvoltages and for information on their selection and application. These devices are to be used in power, telecommunications and/or signalling networks with voltages up to 1000 V a.c. and 1500 V d.c.

Requirements for selection and erection of SPDs in electrical installations of buildings as covered by TC 64 are excluded.