SA Master Installation Electrician cheat sheet

AS/NZS 3000 (Wiring Rules) is given legal force through state/territory electricity legislation and adopted by referral in each jurisdiction's service and installation rules.

The hierarchy is: Act → Regulation → Wiring Rules/Standards → network operator service rules; where documents conflict, the more stringent requirement generally prevails.

AS/NZS 3000 Section 1 sets compliance with fundamental safety principles; Section 2 covers general requirements applying to all installations.

Electrical work must be carried out by, or under supervision of, a licensed electrical worker; the licence class limits the scope of work legally permitted.

AS/NZS 3012 governs construction and demolition sites; AS/NZS 2381 series and AS/NZS 60079 series govern hazardous areas.

Certification of electrical work (CCEW) must be issued for prescribed work, with a copy to the consumer and to the network operator where required.

Standards are amended periodically; designers must confirm the edition referenced by the relevant regulator, not assume the latest edition applies.

Non-compliant work can result in defect notices, disconnection, fines and personal liability for the licensed worker and the contractor.

AS/NZS 3000 defines 'alteration', 'additions' and 'new installation'; additions require the altered circuit to remain compliant as a whole.

Licensed scope: unrestricted electrician may design and connect; restricted classes (e.g. disconnect/reconnect) are limited to defined tasks.

AS/NZS 3008.1.1 provides cable current-carrying capacity tables and derating factors; AS/NZS 3008.1.2 covers larger conductors and conditions.

AS/NZS 3017 sets out verification and testing methods; AS/NZS 3019 covers periodic verification of existing installations.

Mandatory standards referenced in AS/NZS 3000 Clause 1.9 include AS/NZS 3008 (cables), AS/NZS 3017 (testing) and AS/NZS 4836 (safe work on low-voltage).

The maximum demand permitted by the supply authority is set by the network operator; the installation must not exceed the agreed supply capacity.

Definitions: 'final subcircuit' is the circuit from the last protective device to the points; 'main switch' controls the whole installation.

Supervisory obligations require the licensee to ensure unlicensed assistants are directly supervised and work is checked before energisation.

Design sequence: determine load and maximum demand → select protective devices → select cable size for current capacity and voltage drop → verify fault loop and disconnection times → specify earthing and bonding.

Voltage drop limits (AS/NZS 3000): 5% total from point of supply to any point; 5% for consumers mains, 5% for distribution and 5% for final subcircuits as typical apportionment.

Protective device selection requires Ib ≤ In ≤ Iz and I2 ≤ 1.45 Iz, where Ib is design current, In device rating, Iz cable capacity.

Coordination requires the protective device to operate within the required disconnection time at the calculated fault loop impedance.

Design must consider prospective short-circuit current at each point and the device's rated breaking/short-circuit capacity.

Discrimination (selectivity) between upstream and downstream devices is required so a fault operates only the nearest device.

Segregation of circuits and separation of emergency, life-safety and normal supplies must be considered at design stage.

Design documentation must record calculations, assumptions and the basis of selection to support verification and future alteration.

Maximum demand (MD) is the greatest average load over a defined period; it is calculated per AS/NZS 3000 Clause 2.2 and the applicable load tables.

Domestic MD uses diversified load: lighting by floor area, socket outlets by number, plus fixed appliances and controlled load with diversity factors.

For non-domestic installations, MD is the greater of the connected load and the assessed demand using diversity; where unknown, use the connected load.

Three-phase balanced load: total MD in kVA = √3 × line voltage × line current; per-phase kW = Vph × Iph × pf.

Diversity factor reduces connected load to expected demand; it must not be applied where all loads can operate simultaneously.

Motor circuits require MD including starting current effects and may need higher device ratings for starting duty.

Supply capacity check: calculated MD must not exceed the consumer mains and main switch rating and the network operator's agreed capacity.

Record the MD calculation basis; adding load later requires recalculating MD before altering the main switchboard.

Earthing system types: TN-S, TN-C-S (MEN), TN-C, TT and IT; AS/NZS 3000 installations in Australia use MEN (multiple earthed neutral) under TN-C-S.

MEN link connects neutral bar to earth bar at the main switchboard only; a second MEN link downstream creates parallel neutral paths and is non-compliant.

Main earthing conductor size depends on active conductor size per Table 5.1; minimum 4 mm² copper for typical domestic.

Equipotential bonding connects exposed conductive parts, extraneous conductive parts and the earthing system; bonding conductors sized per Table 5.1.

Fault loop impedance Zs = Ze + (R1 + R2) for the circuit; Zs must be low enough for the device to disconnect within the required time.

Maximum disconnection times: 0.4 s for final subcircuits ≤32 A; 5 s for distribution circuits and fixed equipment >32 A (AS/NZS 3000 Table 8.1).

Earth electrode resistance for TT systems must be low enough that RCD protection operates; typically ≤ 100 Ω is a common design target but verify against the standard.

Continuity of the earthing system and protective bonding must be verified by test before energisation.

Overcurrent protection comprises overload (thermal) and short-circuit (magnetic) protection; MCBs combine both, fuses are rated by I2 ≤ 1.45 Iz.

RCDs: 30 mA for socket outlets and personal protection; 300 mA for fire protection; Type AC, A, B, F selection depends on load waveform.

RCDs do not protect against overload or short circuit; they supplement, not replace, overcurrent protection.

Discrimination: time-current curves of upstream and downstream devices must not overlap in the fault current range of interest.

Switchgear ratings: rated current, rated short-circuit breaking capacity (Icn/Ics) and utilisation category must match the prospective fault current.

Isolation requires a device that opens all active conductors with a visible or lockable indication; main switches must be capable of isolation under load.

Control circuits and emergency stop functions must fail safe and be clearly identified; motor protection includes overload, phase failure and stall.

Selectivity can be achieved by current grading, time grading or energy-based (I²t) coordination between devices.

Cable selection requires: design current Ib, protective device rating In, cable capacity Iz, voltage drop, and short-circuit withstand.

Iz = It × derating factors for ambient temperature, grouping, thermal insulation, burial depth and soil thermal resistivity.

Installation methods (AS/NZS 3008) determine the base current-carrying capacity; enclosed in insulation is the most derated method.

Voltage drop: Vd = (2 × I × L × R) / 1000 for single-phase; use √3 factor for three-phase; R includes conductor resistance at operating temperature.

Voltage drop limit is 5% total from point of supply to any point; calculate for the worst-case circuit.

Conductor minimum sizes: 1.0 mm² lighting, 1.5 mm² socket outlets (AS/NZS 3000 Table 3.1 typical minimums); verify against current capacity.

Cable bending radius, mechanical protection and support spacing must comply with the installation method specified.

Underground and buried cables require depth of cover, warning tape and mechanical protection per AS/NZS 3000 and local requirements.

Hazardous areas are classified by zone (gas: Zone 0, 1, 2; dust: Zone 20, 21, 22); equipment must be certified for the zone and gas/dust group and temperature class.

AS/NZS 60079 series governs explosion-protected equipment; AS/NZS 2381 series covers selection and installation; intrinsic safety uses Ex ia/ib.

Medical locations (AS/NZS 3003) require equipotential bonding, isolated supplies in Group 1/2 areas and RCDs with specified sensitivity; body-protected and cardiac-protected areas differ.

Wet areas (bathrooms, showers, pools) require supplementary equipotential bonding, RCD protection and zone-based equipment restrictions per AS/NZS 3000 Section 6.

Swimming pools and spas require equipotential bonding of all conductive parts within the pool zone and RCD protection; AS/NZS 3000 Section 6.3.

Construction and demolition sites (AS/NZS 3012) require RCD protection on all socket outlets, robust cabling, and regular inspection and testing.

Extra-low voltage (ELV) and separated extra-low voltage (SELV) are used in wet and high-risk locations to reduce shock risk.

Temporary installations must be inspected and tested at intervals; records of testing must be maintained on site.

Verification sequence (AS/NZS 3017): visual inspection first, then continuity, insulation resistance, polarity, earth loop impedance, RCD trip time, and functional tests.

Insulation resistance: minimum 1 MΩ at 500 V DC for low-voltage installations (AS/NZS 3000); test between active-neutral, active-earth, neutral-earth with loads disconnected.

Continuity of protective earthing and bonding: test R1+R2 or the protective conductor resistance; results must be within calculated limits.

Polarity: verify active and neutral are correctly connected at each point and the main switch; reversed polarity is a serious defect.

Earth fault loop impedance: measured Zs must not exceed the maximum permitted for the device and disconnection time.

RCD testing: verify trip time and trip current (30 mA device should trip within 300 ms at rated residual current, faster at higher currents).

Commissioning includes energisation checks, phase rotation, functional testing of controls and recording results on the certificate of electrical compliance.

Certification must record test results, date, licensee details and any limitations; records retained for the period required by the regulator.

Fault diagnosis follows a systematic process: gather information, isolate, test, locate, repair, verify and document.

Common faults: open circuit (no continuity), short circuit (low resistance between conductors), earth fault (low resistance to earth), high resistance joints.

Insulation resistance testing locates insulation breakdown; divide-and-conquer by isolating sections to localise the fault.

RCD nuisance tripping causes include moisture ingress, cumulative earth leakage from multiple circuits, and shared neutral faults.

Thermal imaging and voltage drop measurements identify loose connections and overloaded circuits without dismantling.

Maintenance of existing installations uses AS/NZS 3019 periodic verification; intervals depend on installation type and environment.

Repair must restore compliance with the edition of AS/NZS 3000 applicable at the time of the original installation, or upgrade where required.

Document all faults found, repairs made and test results; report unsafe conditions to the owner in writing.

WHS legislation imposes a primary duty of care on persons conducting a business or undertaking (PCBU) to eliminate or minimise risks so far as reasonably practicable.

Hierarchy of control: eliminate, substitute, isolate, engineering controls, administrative controls, PPE (last resort).

Safe work on low-voltage installations follows AS/NZS 4836: isolation, lock-out/tag-out, proving de-energised, and testing before touching.

Test before touch: prove the tester on a known live source, test the circuit, re-prove the tester after testing.

Risk assessment must consider electrical, mechanical, height, confined space, asbestos and environmental hazards before work starts.

Live work is only permitted where justified and controlled; a documented safe work method statement (SWMS) is required for high-risk construction work.

Emergency procedures: first aid for electric shock, CPR, isolation of supply, and reporting of notifiable incidents to the regulator.

PPE and insulated tools must be rated for the voltage; test instruments must be maintained and calibrated.

A contract for electrical work should specify scope, price, variations, timeline, payment terms and warranty; verbal contracts are enforceable but harder to prove.

Consumer guarantees (Australian Consumer Law) require services to be delivered with due care and skill and fit for purpose.

Quotations are fixed offers; estimates are approximate; variations must be agreed in writing before work proceeds.

Supervisory responsibility includes verifying competence of workers, checking work before certification, and maintaining records.

Certificates of electrical compliance are legal documents; issuing one for non-compliant work exposes the licensee to penalties and liability.

Insurance: public liability and contract works insurance protect the contractor; professional indemnity covers design liability.

Record keeping: retain test results, certificates, invoices and correspondence for the statutory period (commonly 7 years for tax and contract records).

Consumer relations: explain the work, provide written quotes, respond to complaints promptly and comply with dispute resolution processes.