Earth Resistance Test
Verifies the grounding system's ability to dissipate current.
What this test verifies
Determines grounding system resistance using fall-of-potential (3-pole) or other methods.
Why it matters
Safety of people and equipment; ensures acceptable step and touch voltages and protection performance.
Typical commissioning stage
Typical stage
Measurement method
- Instrument: earth resistance tester (telurimeter).
- 3-pole method (fall-of-potential) with current and potential stakes at adequate distances.
- Verification with 62% method and/or position sweep to confirm linearity.
- Avoid parallels with other electrodes and coupling; repeat and average readings.
Acceptance criteria
- Target per standard/design (e.g., < 10 Ω in dedicated systems; more demanding in substations).
- Fall-of-potential curve close to linear and minimal influence from stake position.