What is it
Test to verify electrical continuity between two points by measuring the resistance of the conductive path.
Why is it done
Ensures integrity of protective conductors (PE), equipotential bonds, control loops, and joint quality.
How is it done
- Instrument: ohmmeter or micro-ohmmeter (≥200 mA for PE, per IEC 60364).
- Safety: LOTO, capacitor discharge, and isolation of section under test.
- Connection: measure between origin and destination; for PE: ground ↔ earth terminal with Kelvin probes if applicable.
- Best practices: clean terminals, stabilize reading, and perform repeated measurements.
- Recording: stabilized value, conductor length/section, temperature, and observations.
Expected results
- PE/equipotentials: resistance as low as possible (hundreds of mΩ or less depending on length/section).
- Compare with theoretical calculation by resistivity and length; investigate anomalous or unstable values.
- Significant variations between similar points may indicate false contacts or deficient joints.