The field problem
Lower Basement 3 — Groundwater
Permanent groundwater was present in a deep basement, but the original earthing details did not adequately address immersion, corrosion and waterproofing interfaces.
why the obvious answer can be misleading
An earth-pit opening can become a leakage path through the civil waterproofing system. Saline groundwater can also accelerate corrosion and change long-term material performance.
Why it failed
An earth-pit opening can become a leakage path through the civil waterproofing system.
Saline groundwater can also accelerate corrosion and change long-term material performance.
Follow the engineering
Switch between the field condition and the engineering concept. Trace the path and examine what changes.
Inspect the engineering detail
What changes
Use sealed inspection housings/details appropriate to the waterproofing system, select materials for continuous immersion/corrosive exposure, coordinate penetrations with civil waterproofing and preserve maintainability.
Correction & verification
Use sealed inspection housings/details appropriate to the waterproofing system, select materials for continuous immersion/corrosive exposure, coordinate penetrations with civil waterproofing and preserve maintainability.
Verification recorded in the case
- Water-tightness and electrical continuity must both be inspected after installation.
- Record as-built topology and connection points.
- Repeat the measurement or functional test under a defined condition.
- Confirm continuity and mechanical integrity of the corrected path.
- Document instrument/setup, environmental condition and test method.
- Close the NCR/case only when evidence supports the conclusion.
References & project context
References are reproduced from the PIS casebook. Select the governing edition and project acceptance criteria before using them for a design. The diagrams explain the concept, rather than define construction dimensions.
IEC 62561-5 where applicable; IEC 60364-5-54; project waterproofing/material requirements.
PIS reviewed field handbook · PIS-CS-025
View the original social cardThe engineering lesson
Below-grade earthing design is simultaneously an electrical, materials and waterproofing problem.
Take the lesson into your next design review.