Verification & testing
Continuity testing of PE and bonding
How to make sure the protective conductor is continuous all the way
The continuity measurement documents that the protective conductors (PE) and bonding connections are unbroken and have low resistance all the way from the main earthing terminal out to the exposed parts. Without a continuous PE, automatic disconnection does not work.
Make the system de-energised
Continuity is measured without voltage. Make sure the circuit is disconnected before you attach the test leads to the protective conductor.
Use a low-resistance ohmmeter
Use an instrument that measures with a sufficient test current (low-resistance measurement) so a poor joint is not hidden by a small measuring range. An ordinary multimeter resistance measurement is not suitable for documentation.
Compensate for the resistance of the test leads
Zero (calibrate) the instrument's test leads by short-circuiting the probe tips, so their own resistance is subtracted. Otherwise 0.1–0.3 Ω is added to every measurement and distorts the result on short runs.
Measure PE from the main earthing terminal to each outlet
Measure the PE connection from the main earthing terminal/board out to every socket, every switch and every exposed conductive part. The resistance must be low and consistent with the cable's length and cross-section.
Measure the bonding connections
Measure the continuity of the protective bonding to extraneous conductive parts — e.g. metallic water and heating pipes — up to the main earthing terminal. Supplementary bonding in special locations such as bathrooms is also measured.
Assess and find any breaks
An unexpectedly high or infinite resistance means a break or a poor joint — typically a loose terminal or a forgotten PE connection in a box. Find and fix the fault, and measure again.
Document the measurements
Record the continuity measurements (Ω) per connection in the verification report. Continuity in PE is a prerequisite for the other protection tests to be meaningful.
Source
Based on DS/HD 60364-6 (continuity testing).
Videos from NDLA
Video guide· Norwegian speech
Kontinuitetsmåling
Source
NDLA
«Kontinuitetsmåling» · Script: Fred Berglyd · Photographer: Øystein E. Johannessen · Editorial: Bjørnar M. Vik
License: CC BY-SA 4.0 · Original at NDLA ↗
Shown unaltered in the original language with the source's own subtitles. The video shows Norwegian practice — the method is often the same, but rules and standards may differ from the Danish ones.