SA Master Installation Electrician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

MEN link location

The multiple earthed neutral link connects the neutral bar to the earth bar at the main switchboard only. Additional links downstream create parallel neutral paths and are non-compliant.

Fault loop impedance Zs

Zs is the total impedance of the fault loop from the point of fault back to the source. It must be low enough for the protective device to disconnect within the required time.

Maximum disconnection time

Final subcircuits up to 32 A must disconnect within 0.4 s; distribution circuits and fixed equipment above 32 A within 5 s under AS/NZS 3000 Table 8.1.

Voltage drop limit

AS/NZS 3000 limits total voltage drop from the point of supply to any point of installation to 5 percent of nominal voltage for low-voltage installations.

Cable derating factors

Cable current capacity is reduced for ambient temperature, grouping, thermal insulation, burial depth and soil thermal resistivity. Iz equals base capacity times all applicable factors.

Ib In Iz relationship

Design current Ib must not exceed the protective device rating In, which must not exceed the cable capacity Iz. This ensures the cable is protected against overload.

RCD purpose and rating

A residual current device detects earth leakage current and trips. 30 mA devices protect people; they supplement but do not replace overcurrent protection.

Discrimination

Discrimination or selectivity ensures the protective device nearest the fault operates first, preventing unnecessary loss of supply to healthy circuits upstream.

Insulation resistance test

Measure resistance between conductors and to earth at 500 V DC with loads disconnected. A minimum of 1 megohm indicates acceptable insulation for low-voltage installations.

Test before touch

Prove the tester on a known live source, test the circuit to confirm de-energisation, then re-prove the tester after testing to confirm it still works.

Hierarchy of control

Risk controls in order: eliminate, substitute, isolate, engineering controls, administrative controls, then personal protective equipment as the last resort.

Hazardous area zones

Gas atmospheres use Zones 0, 1 and 2 by likelihood of presence; dust atmospheres use Zones 20, 21 and 22. Equipment must be certified for the zone.

Construction site requirements

AS/NZS 3012 requires RCD protection on socket outlets, robust cabling, regular inspection and testing, and records kept on site for construction and demolition installations.

Equipotential bonding

Bonding connects exposed conductive parts and extraneous conductive parts to the earthing system so touch voltages remain at safe levels under fault conditions.

Domestic maximum demand

Calculated using diversified load: lighting by floor area, socket outlets by number, fixed appliances and controlled load with diversity factors from AS/NZS 3000 Clause 2.2.

Three-phase power formula

For a balanced three-phase load, total apparent power in kVA equals the square root of three times line voltage times line current, divided by 1000.

Ib design current

The design current is the current expected to flow in a circuit under normal operating conditions, used as the starting point for protective device and cable selection.

Design sequence

Determine load and maximum demand, select protective devices, select cable for capacity and voltage drop, verify fault loop and disconnection times, then specify earthing and bonding.

Certificate of electrical compliance

A legal document issued by the licensed worker certifying that prescribed electrical work complies with AS/NZS 3000 and relevant standards. Copies go to the consumer and network operator.

AS/NZS 3017 testing

Standard setting out verification methods for low-voltage installations: visual inspection, continuity, insulation resistance, polarity, earth loop impedance and RCD testing.

AS/NZS 3019 periodic verification

Standard for periodic verification of existing installations, setting inspection and testing intervals based on installation type, environment and criticality of use.

Open circuit fault

A break in a conductor path giving no continuity. Diagnosed by continuity testing and isolated by dividing the circuit into sections until the break is located.

RCD nuisance tripping

Cumulative earth leakage from multiple circuits, moisture ingress or shared neutral faults can trip an RCD without a genuine insulation failure.

Licensed scope of work

Each licence class authorises defined electrical work. Unrestricted electricians may design and connect; restricted classes are limited to specified disconnect and reconnect tasks.

Mandatory referenced standards

AS/NZS 3000 Clause 1.9 references AS/NZS 3008 for cables, AS/NZS 3017 for testing and AS/NZS 4836 for safe work on low-voltage installations.

Wiring Rules legal force

AS/NZS 3000 gains legal effect through state and territory electricity legislation and service rules, which adopt it by reference for electrical installations.

Final subcircuit definition

The circuit from the last protective device in the switchboard to the points of consumption, including all cables and accessories connected to that device.

Medical location bonding

AS/NZS 3003 requires equipotential bonding and isolated supplies in Group 1 and 2 medical areas, with RCD sensitivity specified for body and cardiac protected areas.

Quotation versus estimate

A quotation is a fixed offer to perform work at a stated price. An estimate is approximate. Variations to a quotation must be agreed in writing before work proceeds.

Consumer guarantees

Australian Consumer Law requires electrical services to be delivered with due care and skill and to be fit for the purpose made known by the consumer.

Prospective short-circuit current

The current that would flow at a point if a short circuit occurred there. Switchgear breaking capacity and cable withstand must be rated for this value.

Main switch function

The main switch isolates the entire installation from the supply. It must open all active conductors and be capable of isolation under load.