How to review Class I earth-continuity checks
Ask an electrically competent reviewer to agree the relevant accessible metal parts, earth reference, lead compensation and product-specific test settings. Require a separate resistance reading for each agreed part, linked to the tested unit, rather than an overall pass. Use this evidence brief when working with Cambridge China Bridge.
Agree the purpose and reviewer
Class I equipment relies on effective earthing of exposed conducting parts. HSE guidance says that interpreting electrical test results needs appropriate electrical knowledge. Ask who will select the test points and interpret the readings, and request evidence of experience with the product and test instrument.
State whether the evidence is for product assessment, factory production checks or equipment already in use. Do not treat an in-service appliance check as the complete evidence for a new product. Our electrical import guide covers the wider compliance documents.
Map the relevant accessible metal parts
Ask the reviewer to mark the earth reference and each relevant accessible metal part on photographs or a drawing. Consider separate panels, doors, handles and assemblies with distinct bonding paths. Ask for a reason wherever accessible metal is excluded; appearance alone does not establish whether a part relies on protective earthing.
Have the reviewer select safe, repeatable contact points and explain how coatings, hinges and removable parts affect the measurement. A convenient screw may not establish continuity to the surrounding panel. If there is no suitable accessible point, request an agreed specialist method rather than instructing an inspector to scrape finishes or dismantle the product.
Check lead-resistance compensation
Ask how resistance from the measuring leads and fixtures is accounted for. Request the instrument’s compensation procedure, the lead check reading and confirmation that the same leads and fixtures were used for the product measurements. Recheck compensation after changes to the measurement setup.
Distinguish the tester’s leads from the product’s protective conductor. Ask whether the measurement includes the supplied mains cord or starts at the appliance inlet, and record the cord used. Do not subtract the product cord’s resistance simply because the instrument offers a lead-zero function.
Agree settings and acceptance criteria
Before testing, ask the competent reviewer to identify the applicable product test method and its acceptance criteria, with the document edition and clause. Request the test current, voltage setting or limit, duration, instrument mode and resistance limit. Do not substitute a generic appliance-tester preset for a justified product-specific method.
Have the reviewer confirm that the method suits sensitive circuitry and that the unit is safely isolated for the continuity check. Agree whether readings are raw or compensated and how unstable readings will be investigated. Use our test-report verification guide to check the report’s identity and scope.
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Require readings you can trace
Request a record for each tested unit showing its model, batch or serial identity, instrument identity, calibration status, operator, date, earth reference and setup. For each agreed metal part, require its photograph or point label, resistance reading with units, compensation status, acceptance criterion and result. An overall pass leaves the coverage unclear.
Hold inspection approval if points are missing, readings are unstable or the setup is unexplained. Request the original failed readings, corrective action and linked retest results. Ask Cambridge China Bridge’s staff in China to obtain the factory records and point photographs, with specialist interpretation arranged through our testing and certification service.
Frequently asked questions
Which metal parts should an earth-continuity check cover?
Ask a competent reviewer to identify each accessible part that relies on protective earthing. Require a point map and reasons for exclusions, including separate panels and assemblies with distinct bonding paths.
Should test-lead resistance be subtracted?
Ask for the instrument’s compensation procedure and lead check record. Distinguish measuring leads from the product’s mains cord, and avoid compensating the same resistance again.
What test current and resistance limit should I specify?
Ask the competent reviewer to justify the settings and limit against the applicable product test method. Record the method, edition, clause and duration instead of choosing a generic preset.
Is an overall earth-continuity pass enough?
For your inspection brief, request a resistance reading for every agreed metal part, linked to the tested unit and setup. An overall pass does not show which parts were checked.