Electrical Materials and Tools
What is tested
Identification, specification and correct use of conductors, insulators, wiring materials, hand tools and personal protective equipment.
Materials
Copper conducts about 1.7 times better than aluminium and is used for contacts and small wiring; aluminium is lighter and cheaper and is common in service mains and overhead lines, but needs oxide-inhibiting paste and bimetal connectors. PVC insulation is standard up to 70 °C; XLPE withstands 90 °C. Porcelain, bakelite and FRP are used for insulators and switch bodies. Conduit comes in 20, 25 and 32 mm PVC or GI; flexible conduit is used at motor terminals. Solder is 60/40 tin-lead with resin flux - never acid flux on copper wiring.
Tools
Combination and long-nose pliers, side cutters, insulated screwdrivers of the correct blade size, hammer, chisel, hacksaw, steel rule, try square, wire stripper, crimping tool, soldering iron, fish tape, blow lamp for conduit bending, test lamp, multimeter, megger, earth tester and clamp meter.
Worked example
Terminating a 4 mm² stranded copper conductor into a 16 A socket: strip about 12 mm of insulation with a wire stripper, not pliers; twist the strands lightly; insert fully into the terminal; tighten to a firm nip; pull gently to confirm. For a motor lug, crimp with the matching die and cover with heat-shrink - never solder a crimp lug.
Traps
Using acid flux or an oversize screwdriver; stripping with pliers and nicking copper strands; and treating an insulation tester as a continuity tester.