Fault Diagnosis, Maintenance and Repair
Fault diagnosis is systematic, not guesswork. The method: gather information (what changed, when it fails, symptoms), form a hypothesis, test to confirm or eliminate, then repair and verify. Use the correct instrument for the job - insulation tester, low-resistance ohmmeter, multimeter, clamp meter, RCD tester - and always isolate and prove dead before working on circuits.
Common fault categories: open circuit (broken conductor, loose terminal), short circuit (insulation failure, crossed conductors), earth fault (insulation breakdown to earth), high resistance joints (heat, voltage drop, intermittent faults), and protective device nuisance tripping (overload, inrush, faulty appliance, RCD sensitivity). Maintenance includes periodic inspection and testing, thermal imaging where appropriate, tightening terminals to specification, and recording results.
Traps: replacing a device without finding the cause (the fault returns); using a multimeter's continuity buzzer as proof of low resistance (it is not a measured value); failing to test after repair; and overlooking that intermittent faults often come from loose connections or moisture ingress, which require physical inspection, not just electrical tests.
Worked example: An RCD trips intermittently. Isolate, then test the RCD itself (trip time and current), then insulation resistance on each circuit to find leakage, then inspect for moisture or damaged cable. If the RCD tests correctly and one circuit shows low insulation resistance, the fault is in that circuit - repair, retest, and record.
Work Health and Safety, Risk Control and Safe Work Practices
WHS law requires a hierarchy of control: eliminate the hazard, then substitute, engineer, administratively control, and finally use PPE as the last line. Electrical work adds specific duties: isolation and lock-out/tag-out, proving dead, testing before touching, and using AS/NZS 4836 for safe work on low-voltage installations. Risk assessment is documented, and workers must be consulted.
Key concepts: PCBU duties (primary duty of care), officer due diligence, worker consultation, incident notification, and the requirement to manage risks so far as reasonably practicable. Safe work practices include identifying services before excavation, maintaining safe approach distances, using insulated tools and tested equipment, and ensuring emergency and rescue arrangements (especially for live work, which should be avoided).
Traps: treating PPE as the primary control; assuming a lock-out is complete when multiple supply sources exist (e.g. solar, generators, UPS); forgetting that proving dead must be done with a proven tester on a known live source first and again after; and missing the duty to notify regulators of notifiable incidents.
Worked example: Before working on a switchboard fed by mains and a solar inverter, identify all sources, isolate and lock each, prove the tester on a known source, test for dead at all points, then apply locks and tags. PPE is worn throughout, but isolation and proving dead are the controls that make the work safe.
Business, Contract, Supervisory and Consumer Relations Responsibilities
This domain tests the commercial and professional side of electrical work. You must understand contract formation (offer, acceptance, consideration), the difference between a quote and an estimate, variations, and the importance of written terms. Consumer law (the Australian Consumer Law) implies guarantees - work must be done with due care and skill, and materials must be fit for purpose. Insurance (public liability, contract works, professional indemnity) and licensing conditions are part of running a compliant business.
Supervisory responsibilities include allocating competent workers, verifying work, maintaining records, and ensuring safety and compliance on site. Consumer relations include clear communication, transparent pricing, handling complaints, and providing certification and documentation on completion. Privacy of customer information and fair dealing are also examinable.
Traps: treating an estimate as a fixed price (it is not); starting work without a written contract or variation process; assuming the contractor is not liable for defective work because the client supplied materials; and failing to document supervision and verification, which undermines both compliance and defence in a dispute.
Worked example: A client asks for extra power points after the quote. The correct approach: document the variation in writing (scope, price, time impact), get agreement before proceeding, then update the certificate and records at completion. Proceeding verbally exposes both parties to dispute and may leave the contractor unpaid for the extra work.