Hardware Components and Basic Maintenance
What this domain tests
Hardware Components and Basic Maintenance tests identification of switches, sockets, holders, DBs, MCBs, contactors, relays and terminals, and the preventive and corrective maintenance needed to keep them reliable.
Core rules
- A contactor switches a heavy load with a small control current; a relay does the same at lower power. The coil voltage and contact rating must match the circuit.
- Terminal blocks and cable glands must grip the conductor and the cable sheath. A loose terminal heats; a tight one compresses the strands without cutting them.
- Preventive maintenance includes isolating, inspecting for discolouration, tightening terminals to the maker’s torque, cleaning dust, checking insulation resistance and replacing worn parts.
- Fault finding follows a sequence: observe, isolate, test for dead, check continuity, check voltage, check insulation, then repair and retest.
- Keep spares of the same rating; a wrong MCB or socket rating is a defect, not a repair.
- Record the work done and the readings taken.
Worked example
A socket outlet feels hot and the plug has darkened. Isolate the circuit and prove dead. Inspect the terminals; a loose neutral screw has caused arcing. Cut back the burnt conductor, re-terminate with the correct torque, replace the socket if the plastic is carbonised, and retest insulation and polarity before energising.
Traps that cost marks
Ignoring discolouration as “normal”; replacing a 16 A MCB with a 32 A one; mixing copper and aluminium conductors in one terminal; and doing maintenance without lock-off.