Tools, Measuring Instruments and Workshop Practice
What this domain tests
This domain tests correct selection, care and use of hand tools and measuring instruments: multimeter, clamp meter, insulation tester, earth tester, soldering equipment and bench practice.
Core rules
- Use VDE-insulated screwdrivers and pliers on electrical work; never use a screwdriver as a chisel or a plier as a hammer.
- A digital multimeter measures voltage, resistance and continuity; current measurement needs the correct range and the probes moved to the current sockets. A clamp meter is for current without breaking the circuit and is usually AC-only unless marked.
- An insulation tester (megger) applies 500 V DC for 230 V circuits. A healthy domestic circuit should read at least 1 MΩ between live/neutral and earth; lower values indicate moisture, damage or contamination.
- Check test leads, zero the meter where required, and never measure resistance or continuity on a live circuit.
- Keep the bench dry, well lit and uncluttered; store tools clean and calibrated; use a soldering stand and fume extraction.
Worked example
A geyser circuit reads 0.3 MΩ from live-plus-neutral to earth on a 500 V insulation test. The minimum is 1 MΩ, so the circuit fails. Reasoning: disconnect the geyser and retest the wiring. If the wiring is good, test the element and thermostat; a damp terminal box or a cracked element can pull insulation down. Dry, repair or replace the faulty part, then retest before energising.
Traps that cost marks
Putting the multimeter on the current range and connecting it across 230 V; testing resistance with the supply on; forgetting to prove a voltage tester before and after use; using a megger on electronic boards; and accepting a continuity beep as proof of insulation quality.