QLD Electrical Licence cheat sheet

Ohm's law: V = I × R; I = V/R; R = V/I for resistive circuits.

Power: P = V × I = I²R = V²/R; single-phase real power P = V I cosφ.

Three-phase balanced load: P = √3 × V_L × I_L × cosφ; apparent power S = √3 × V_L × I_L.

Impedance Z = √(R² + X²); X_L = 2πfL; X_C = 1/(2πfC).

Series circuit: same current through all components; R_total = R1 + R2 + ...

Parallel circuit: same voltage across branches; 1/R_total = 1/R1 + 1/R2 + ...

Australian LV supply is nominally 230 V phase-to-neutral, 400 V phase-to-phase, 50 Hz.

Power factor = cosφ = P/S; lagging power factor can be corrected with capacitors.

AS/NZS 3000 (Wiring Rules) sets minimum requirements for design, selection, installation, verification and maintenance of electrical installations.

MEN system: neutral and protective earth are connected at the point of supply only; earth bar and neutral link remain separate at switchboards.

Protective earthing must connect exposed conductive parts to the earthing system; equipotential bonding is required for metallic services.

RCDs with 30 mA maximum residual current are required for socket-outlet and lighting final subcircuits in specified locations; check current edition exceptions.

Voltage drop from the point of supply to any point generally must not exceed 5% of nominal voltage for LV installations.

Cable cross-sectional area is selected for current-carrying capacity, voltage drop, protective device coordination and installation conditions.

Maximum demand is calculated using diversity and AS/NZS 3000 methods, not simply by adding all connected loads.

Segregation of electrical, communications and data cables is required to prevent interference and unsafe contact.

IP rating: first digit indicates protection against solids and dust (0-6); second digit indicates protection against water (0-9K).

Electrical Safety Act 2002 (Qld) imposes duties to ensure electrical safety and to eliminate or minimise electrical risks so far as reasonably practicable.

Electrical Safety Regulation 2013 (Qld) supports the Act, covers licensing and safety requirements, and calls up AS/NZS 3000.

The Electrical Safety Office (ESO) administers Queensland electrical safety laws, licensing, investigations and compliance.

Electrical work must be carried out by a licensed electrical worker; an electrical contractor licence is required for electrical contracting.

Apprentices and trainees must be supervised according to their competency and licence conditions.

Work health and safety duties also arise under the Work Health and Safety Act 2011 (Qld).

Serious electrical incidents and dangerous events must be notified to the Electrical Safety Office or WorkSafe Queensland as required.

Licence classes define the scope of electrical work that may legally be performed.

Visual inspection before testing: check connections, enclosures, labels, damage, IP integrity and earthing.

Test sequence: protective earthing continuity, insulation resistance, polarity, earth fault loop impedance, RCD operation, then energise.

Insulation resistance test at 500 V DC with installation isolated; LV circuits should generally achieve at least 1 MΩ.

Continuity of protective earthing: low-resistance path from earth bar to exposed conductive parts, tested with a low-resistance ohmmeter.

Polarity: active conductors switched and connected correctly; neutrals not switched; socket outlets wired to correct terminals.

Earth fault loop impedance must be low enough for the protective device to operate within the required disconnection time.

RCD test: confirm the device trips at its rated residual current and within the required time.

Use calibrated instruments and prove the voltage tester before and after testing for dead.

After testing, record results, complete required certification, and restore covers and labels.

Hierarchy of control: eliminate, substitute, engineering controls, administrative controls, then PPE as the last resort.

Isolate, lock out, tag out and test for dead before work; prove the tester on a known live source.

Treat all conductors as live until tested and isolated; maintain safe approach distances.

Use a SWMS or JSA for high-risk electrical work, identifying hazards, controls and responsibilities.

PPE may include insulated gloves, arc-rated clothing, safety glasses and hearing protection as risk assessment requires.

Arc flash risk: isolate upstream, use remote operation and keep clear of energised equipment; avoid solo live work.

Electric shock response: isolate supply, call emergency services, start CPR and use a defibrillator if trained.

Report hazards, incidents and near misses; isolate damaged equipment and tag it out.

Test instruments must be rated for the category and voltage and inspected before use.