Vocational Practical / Skill Component
Vocational Practical / Skill Component
The practical component tests safe workshop performance: using a multimeter, wiring a lamp and socket circuit, earthing, insulation testing, reading a motor nameplate, and locating simple faults. Marks are lost for unsafe sequencing even when the final circuit works.
Core skills and rules
- Select the correct function and range before touching probes. Voltage is measured in parallel; current in series; resistance with the circuit dead, isolated and discharged.
- In a one-way lighting circuit, the phase goes to the switch, then to the lamp, and the neutral returns from the lamp. The switch must not be in the neutral.
- For a three-pin socket, connect phase, neutral and earth to the correct terminals; the earth pin is longer and must reach the metal enclosure.
- Indian convention: phase red/yellow/blue, neutral black, protective earth green/yellow.
- Use a megger for insulation resistance after isolation; never test a live circuit. Discharge capacitors before handling.
- Read the motor nameplate: voltage, frequency, current, speed, insulation class and star/delta connection. Match the winding connection to the supply.
- Apply lockout/tagout, insulated tools and PPE before opening an enclosure.
Worked example
You must wire one lamp controlled by a one-way switch and prove it safe. Isolate the supply. Connect phase to switch terminal L1; connect switch L2 to the lamp holder centre contact; connect the lamp holder screw contact to neutral; connect the metal enclosure to earth. Set the multimeter to continuity and confirm switch operation. With the switch off, test from lamp centre contact to neutral: it must read no continuity. If it reads continuity, the switch is in the neutral - the lamp holder remains live when switched off and the work must be corrected.
Traps that cost marks
Selecting current range and placing probes across the supply causes a short circuit. Using an ohmmeter on a live circuit damages the meter. A switch in the neutral is a dangerous wiring error. Skipping isolation, lockout or PPE loses practical marks before testing begins.