Most electrical substations will utilize air-insulated designs, where the live components are exposed. The equipment in the substation must be positioned to maintain adequate spacing between live parts and other substation components, whether grounded or not. Adequate spacing is essential to protect both operating and maintenance staff, minimizing the risk of electrical hazards and preventing the formation of unintended conductive paths between phases. The required safety clearances, which vary depending on voltage levels, are detailed in the following table.
Safety Clearances in Substation
| Minimum Clearances (mm) | 765 kV | 400 kV | 220 kV | 132kV | 33kV |
| Phase to Phase | 9400 | 4200 | 2100 | 1300 | 320 |
| Phase to earth | 6400 | 3500 | 2100 | 1300 | 320 |
| Sectional Clearance | 10300 | 6500 | 5000 | 3800 | 3000 |
| Ground Clearance | 14000 | 8000 | 5500 | 4800 | 3700 |
- Phase-to-phase clearance refers to the minimum distance required between the live components of different phases or within the same phase.
- Phase-to-earth clearance is the minimum distance needed between live parts of the system and grounded structures.
- Sectional clearance is the distance between live parts and the terminals of the section where work is being conducted, ensuring a safe area for maintenance or operational tasks, which may include a platform or ground surface.
- Ground clearance refers to the vertical distance between live equipment components and the surface of the earth.
