This part of IEC 61936 provides@ in a convenient form@ common rules for the design and the erection of electrical power installations in systems with nominal voltages above 1@5 kV d.c.@ so as to provide safety and proper functioning for the use intended. This technical specification does not apply to the design and erection of any of the following: ?C overhead and underground lines between separate installations; ?C electric railways; ?C mining equipment and installations; ?C installations on ships and off-shore installations; ?C electrostatic equipment (e.g. electrostatic precipitators@ spray-painting units); ?C test sites; ?C medical equipment@ e.g. medical X-ray equipment; ?C valve hall. This technical specification does not apply to the design of factory-built@ type-tested switchgear for which separate IEC standards exist. This technical specification does not apply to the requirements for carrying out live working on electrical installations. This technical specification does not apply to the design of factory-built@ type-tested thyristor valves@ VSC valves and switchgear for which separate IEC standards exist.