| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. EARTH PIT DESIGN & LOCATION | |||
| A1 | Earth pit is located away from building foundation, not under building or expansion paths Acceptance: Pit minimum 1.5 m from building, not under future expansion areas, away from wet/flood zones | Cl. 4.2.1 — Pit location | OK NC NA HOLD |
| A2 | Earth pit dimensions are adequate: minimum 1.0 m × 1.0 m × 2.5 m deep (for single-rod system) Acceptance: Pit area ≥ 1.0 m × 1.0 m, depth ≥ 2.5 m, depth to GWT ≤ 2 m (check in dry season) | Cl. 4.3.1 — Pit dimensions | OK NC NA HOLD |
| A3 | Earth pit is free from obstruction; no rocks, debris, or clay layers blocking electrode insertion Acceptance: Pit excavated to full depth, bottom 0.5 m filled with charcoal-coke mixture or conductive backfill | Cl. 4.3.2 — Pit preparation | OK NC NA HOLD |
| A4 | Conductive backfill (charcoal/coke + salt mixture) is used around electrode to improve conductivity Acceptance: Charcoal + salt + soil mix placed in 0.5 m layers, compacted, total depth ≥ 1.0 m above electrode | Cl. 4.4.1 — Backfill material | OK NC NA HOLD |
| A5 | Top portion of pit is covered with 0.5 m soil and finished level; a cover/grate prevents water stagnation Acceptance: Pit covered with grate or stone slabs to prevent water collection, top soil layer 0.5 m | Cl. 4.3.3 — Pit finishing | OK NC NA HOLD |
| B. EARTH ELECTRODES | |||
| B1 | Electrode material is copper rod (min. 16 mm diameter) or GI rod (min. 25 mm diameter); surface is not corroded or damaged Acceptance: Copper: min. Ø 16 mm, GI: min. Ø 25 mm, no corrosion/pitting visible, IS marked | Cl. 4.5.1 — Electrode material | OK NC NA HOLD |
| B2 | Electrode is driven vertically into pit without bending; if bent, electrode is replaced Acceptance: Rod vertical or within 15° from vertical, no bends or kinks, fully seated into pit | Cl. 4.5.2 — Electrode installation | OK NC NA HOLD |
| B3 | For high-resistance soils or large installations, multiple electrodes are used and spaced minimum 2 m apart Acceptance: If multiple electrodes: spacing ≥ 2 m, all connected in parallel with minimum junction resistance | Cl. 4.6.1 — Multi-electrode design | OK NC NA HOLD |
| B4 | Electrode to conductor connection is sound: crimped or soldered (not twisted), protected from corrosion Acceptance: Connection crimped/welded (not twisted), lug/terminal secure, corrosion protection applied if exposed | Cl. 4.7.1 — Electrode connection | OK NC NA HOLD |
| B5 | Earth pit is accessible for periodic maintenance and re-testing; no permanent structures over pit Acceptance: Pit accessible, grate/cover removable, no permanent structures blocking access for testing | Cl. 4.8.1 — Maintenance access | OK NC NA HOLD |
| C. EARTH CONDUCTOR SIZING & ROUTING | |||
| C1 | Main earth conductor from pit to DB is adequately sized: minimum 16 mm² for copper or 25 mm² for GI Acceptance: Copper: min. 16 mm², GI: min. 25 mm², capacity ≥ 1.5 × main switch rating | Cl. 5.2.1 — Main earth conductor size | OK NC NA HOLD |
| C2 | Earth conductor is routed in conduit/tray for mechanical protection; not exposed in walkways Acceptance: Earth conductor in conduit/tray, or buried underground ≥ 0.5 m, not exposed in traffic areas | Cl. 5.3.1 — Earth conductor protection | OK NC NA HOLD |
| C3 | Earth conductor is color-coded green or green-yellow throughout its length Acceptance: Entire earth conductor length marked green or green-yellow, clear and legible | Cl. 5.1.1 — Color identification | OK NC NA HOLD |
| C4 | Circuit earth conductors from DB to load outlets are sized per load: minimum 2.5 mm² for ≤63 A, minimum 4 mm² for >63 A Acceptance: Earth size: ≤63A → 2.5 mm²; 63-125A → 4 mm²; >125A → 6 mm² or larger | Cl. 5.4.1 — Circuit earth conductor sizing | OK NC NA HOLD |
| C5 | Earth conductor joints/connections are properly crimped/soldered with adequate current capacity Acceptance: All joints crimped with appropriate lug, torque verified (M6 ≥ 2.5 Nm), no loose or corroded connections | Cl. 5.5.1 — Earth connection quality | OK NC NA HOLD |