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Substation Clearances: 138KV
Minimum electrical clearances for outdoor air-insulated substations per NESC Rule 235 and IEEE Std 1427. Includes phase-to-ground, phase-to-phase, fence, roadway and walkway clearances by voltage class.
| voltage class | bil basis kV (kV) | clearance over roadway ft (ft) | clearance over walkway ft (ft) | clearance to fence ft (ft) | min phase ground clearance in (in) | min phase phase clearance in (in) | nesc rule | standard |
|---|---|---|---|---|---|---|---|---|
| 138KV | 650 | 22.5 | 16.5 | 10 | 28 | 34 | NESC 235 | IEEE Std 1312 / NESC 2023 |
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