: It defines the "minimum distances" required between live parts (phase-to-phase) and between live parts and the earth (phase-to-earth) to prevent sparkovers.
Imagine you are designing a 33 kV gas-insulated switchgear (GIS) substation for a solar PV plant. You open your to Section 5 (Clearances) and Section 7 (Earthing). You determine: iec 61936-1 pdf