This International Standard IEC 61958 is applicable to voltage presence indicating systems (VPIS) incorporated in a.c. switchgear and controlgear covered by IEC 60298 or IEC 60466. Voltage presence indicating systems are devices used to provide information to operators about the voltage condition of the main circuit of the switchgear in which they are installed. The indication of VPIS alone is not sufficient to prove that the system is dead: if operating procedures make it mandatory, relevant voltage detectors according to IEC 61243 shall be used. This standard is also applicable to phase comparators specifically designed for use with VPIS.