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gh-ctvet-cert-ii-electrical study materials
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gh-ctvet-cert-ii-electrical: Tools and Test Instruments

gh-ctvet-cert-ii-electrical · Work through your exam, one topic at a time.

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Tools and Test Instruments

Tools and Test Instruments tests safe selection, use, checking and interpretation of hand tools and electrical test equipment. Questions cover insulated tools, proving units, multifunction testers, insulation resistance, continuity, loop impedance, RCD testing, calibration and recording results.

Core rules

  • Hand tools: insulated screwdrivers rated to IEC 60900 (1000 V), side cutters, pliers, crimping tools, cable strippers, conduit benders and hole saws. Insulated tools with cuts or cracks must be withdrawn from service.
  • Test leads to GS38: fused, shrouded tips with no more than about 4 mm exposed, finger guards, and a continuous rating suitable for the installation.
  • A two-pole voltage indicator with a proving unit is the approved way to prove dead. A non-contact voltage detector is a supplementary aid only.
  • Calibration: check the certificate and due date before use; zero or null the leads for continuity tests; record instrument identity with results.
  • Insulation resistance: 500 V DC on 230/400 V circuits, minimum 1 megohm, with the circuit isolated, sensitive equipment disconnected and lamps removed.
  • Continuity: low-resistance ohmmeter, leads nulled; record R1+R2 and verify protective conductors are connected.

Worked example

Insulation resistance test on a domestic socket radial. Isolate and lock off, prove dead, unplug appliances, remove lamps and neon indicators, then test L-E, N-E and L-N at 500 V DC. Results: L-E 250 megohm, N-E 250 megohm, L-N 300 megohm. All exceed 1 megohm, so the circuit passes. If L-E read 0.3 megohm, investigate moisture in a back box, a damaged cable or a borrowed neutral, and do not energise until repaired and retested.

Traps

  • Using a multimeter in resistance mode on a live circuit.
  • Failing to prove the voltage indicator before and after testing dead.
  • Testing insulation resistance with electronics, surge protection or dimmers still connected.
  • Reporting a pass without recording calibration details and test conditions.
  • Relying on a non-contact detector as proof of isolation.