The field problem
Central Telecommunications Facility
The facility experienced unstable resistance readings, buzzing/noise and interference.
Tower earthing and LV earthing were separate and uncoordinated.
why the obvious answer can be misleading
Separate electrodes can still couple through cable screens, PE conductors and equipment. Lack of equipotential coordination was therefore a credible contributor to voltage differences and common-mode disturbance, though not claimed as the sole cause without before/after evidence.
Why it failed
Separate electrodes can still couple through cable screens, PE conductors and equipment.
Lack of equipotential coordination was therefore a credible contributor to voltage differences and common-mode disturbance, though not claimed as the sole cause without before/after evidence.
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
Develop controlled equipotential bonding; verify conductor sizing and continuity; review down-conductor routing, separation distance and soil-resistivity assumptions; then correlate electrical changes with system behaviour.
Correction & verification
Develop controlled equipotential bonding; verify conductor sizing and continuity; review down-conductor routing, separation distance and soil-resistivity assumptions; then correlate electrical changes with system behaviour.
Verification recorded in the case
- Measure potential differences/current paths and repeat functional checks after corrective bonding.
- 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 60364-5-54; IEC 62305; IEC 62305-4/EMC concepts as applicable.
PIS reviewed field handbook · PIS-CS-036
View the original social cardThe engineering lesson
In telecom facilities, earthing is an EMC architecture as well as a safety system.
Take the lesson into your next design review.