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SA Master Installation Electrician study materials
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SA Master Installation Electrician practice questions

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Question 1Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which document is the primary Australian/New Zealand standard for electrical installations?

  1. AS/NZS 3008
  2. AS/NZS 3017
  3. AS/NZS 4836
  4. AS/NZS 3000 Correct answer.

Explanation

AS/NZS 3000, known as the Wiring Rules, sets out the requirements for the design, construction and verification of electrical installations. The other standards cover different aspects such as cable selection or safe work practices.

Question 2Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the minimum degree of protection required for an electrical enclosure installed in a residential outdoor location exposed to weather?

  1. IP56
  2. IP67
  3. IP44 Correct answer.
  4. IP23

Explanation

AS/NZS 3000 requires that equipment exposed to weather be provided with a degree of protection of at least IP44, which protects against solid objects greater than 1 mm and splashing water. Higher ratings may be needed in more severe conditions.

Question 3Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Under AS/NZS 3000, what is the maximum permissible voltage drop for a consumer service from the point of supply to the main switchboard?

  1. 7%
  2. 2% Correct answer.
  3. 5%
  4. 3%

Explanation

The standard specifies a maximum voltage drop of 2% for a consumer service or consumer mains between the point of supply and the main switchboard. This ensures that the total voltage drop at the installation is kept within acceptable limits.

Question 4Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which type of protection is required for a person working on or near live electrical equipment where it is not practicable to isolate the supply?

  1. Basic insulation
  2. Double insulation
  3. RCD
  4. Safety observer Correct answer.

Explanation

AS/NZS 4836 requires that a safety observer be used when work is performed on or near live equipment and isolation is not practicable. The observer's role is to warn and assist the worker in case of danger.

Question 5Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the standard frequency for inspection and testing of electrical installations in a hazardous area according to AS/NZS 60079.14?

  1. Every 5 years
  2. Every 2 years
  3. Every 6 months Correct answer.
  4. Every 12 months

Explanation

AS/NZS 60079.14 recommends that hazardous area installations be inspected at intervals not exceeding 6 months for initial and periodic inspections, unless a risk assessment justifies a different interval. This frequent inspection helps maintain the integrity of explosion-protection measures.

Question 6Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which AS/NZS standard provides requirements for the selection and installation of electrical equipment in explosive atmospheres?

  1. AS/NZS 3010
  2. AS/NZS 2381.1
  3. AS/NZS 3000
  4. AS/NZS 60079.14 Correct answer.

Explanation

AS/NZS 60079.14 specifically covers the design, selection, erection, inspection and maintenance of electrical installations in explosive atmospheres. It is part of the AS/NZS 60079 series for explosive atmospheres.

Question 7Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the maximum residual current rating for a residual current device (RCD) used for personal protection in a final subcircuit?

  1. 30 mA Correct answer.
  2. 300 mA
  3. 100 mA
  4. 10 mA

Explanation

AS/NZS 3000 requires that RCDs used for personal protection in final subcircuits have a rated residual operating current not exceeding 30 mA. This level is considered to provide effective protection against electric shock.

Question 8Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which of the following is required to be documented in a switchboard schedule?

  1. The colour of the switchboard enclosure
  2. The rating of each protective device Correct answer.
  3. The date of the last inspection
  4. The name of the installing electrician

Explanation

AS/NZS 3000 requires that a switchboard schedule be provided, listing the circuits and the rating of each protective device. This information is essential for safe operation and maintenance.

Question 9Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the minimum size of earthing conductor required for a consumer main with a cross-sectional area of 70 mm² copper?

  1. 6 mm²
  2. 35 mm² Correct answer.
  3. 16 mm²
  4. 70 mm²

Explanation

According to AS/NZS 3000 Table 5.1, the minimum size of the earthing conductor for a consumer main with a cross-sectional area of 70 mm² copper is 35 mm². The table specifies sizes based on the active conductor size.

Question 10Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

In AS/NZS 3000, what does the term 'MEN' stand for?

  1. Multiple Earthed Neutral Correct answer.
  2. Metallic Equipment Neutral
  3. Mandatory Earth Neutral
  4. Main Earthing Node

Explanation

MEN stands for Multiple Earthed Neutral, a system where the neutral conductor is connected to earth at multiple points, including at the main switchboard and at each consumer's point of supply. This ensures a low-impedance path for fault currents.

Question 11Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the maximum disconnection time for a final subcircuit protected by a 30 mA RCD in a TN-S system?

  1. 0.5 s
  2. 0.4 s
  3. 0.1 s Correct answer.
  4. 5 s

Explanation

For a final subcircuit protected by a 30 mA RCD, the maximum disconnection time is 0.1 seconds, as the RCD operates very quickly. This is specified in AS/NZS 3000 to limit the duration of electric shock.

Question 12Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which AS/NZS standard provides requirements for the installation of electrical equipment on construction and demolition sites?

  1. AS/NZS 3010
  2. AS/NZS 3000
  3. AS/NZS 3019
  4. AS/NZS 3012 Correct answer.

Explanation

AS/NZS 3012 sets out the requirements for electrical installations on construction and demolition sites, including additional protection measures such as RCDs. It supplements the general requirements of AS/NZS 3000.

Question 13Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the minimum clearance required between a low-voltage overhead conductor and a building structure under AS/NZS 3000?

  1. 2.0 m
  2. 1.5 m
  3. 1.0 m Correct answer.
  4. 0.6 m

Explanation

AS/NZS 3000 Table 3.4 specifies a minimum clearance of 1.0 m between low-voltage overhead conductors and building structures for voltages up to 1 kV. This clearance helps prevent contact and ensures safety.

Question 14Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which of the following is a requirement for a main earthing conductor according to AS/NZS 3000?

  1. It must be coloured green
  2. It must be connected to the neutral bar at the main switchboard Correct answer.
  3. It must be at least 6 mm² copper
  4. It must be protected by a 30 mA RCD

Explanation

In a MEN system, the main earthing conductor is connected to the neutral bar at the main switchboard to create the multiple earthed neutral point. This connection is essential for the proper operation of protective devices.

Question 15Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the purpose of the AS/NZS 3000 requirement for 'basic protection'?

  1. To protect against indirect contact
  2. To protect equipment from overvoltage
  3. To provide backup protection against failure of basic insulation
  4. To protect against direct contact with live parts Correct answer.

Explanation

Basic protection, also known as protection against direct contact, is intended to prevent persons from touching live parts under normal conditions. It is achieved through insulation, barriers, enclosures or distance.

Question 16Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which of the following is an example of a 'prescribed electrical installation' under the Wiring Rules?

  1. A commercial office with a total floor area of 100 m²
  2. A domestic shed with no electrical supply
  3. A single-family house
  4. A carnival float with electrical equipment Correct answer.

Explanation

Prescribed electrical installations include those in areas with special risks, such as carnivals, fairs, and other temporary installations. A carnival float with electrical equipment falls into this category and requires additional safety measures.

Question 17Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the maximum interval for periodic verification of a commercial electrical installation according to AS/NZS 3019?

  1. 1 year
  2. 5 years Correct answer.
  3. 10 years
  4. 2 years

Explanation

AS/NZS 3019 recommends that commercial installations be periodically verified at intervals not exceeding 5 years. This helps ensure ongoing safety and compliance.

Question 18Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which of the following is a requirement for the installation of a switchboard under AS/NZS 3000?

  1. It must be provided with a switchboard schedule Correct answer.
  2. It must be labelled with the maximum demand
  3. It must be located in a locked room
  4. It must have a minimum clearance of 1 m in front

Explanation

AS/NZS 3000 requires that a switchboard be provided with a schedule that identifies each circuit and the rating of its protective device. This schedule aids in safe operation and maintenance.

Question 19Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

What is the minimum size of a copper protective earthing conductor for a 20 A final subcircuit with a 2.5 mm² active conductor?

  1. 4.0 mm²
  2. 1.5 mm²
  3. 2.5 mm² Correct answer.
  4. 1.0 mm²

Explanation

AS/NZS 3000 Table 5.1 requires that the protective earthing conductor be at least the same size as the active conductor for active conductors up to 16 mm². Therefore, for a 2.5 mm² active, the earthing conductor must be at least 2.5 mm².

Question 20Electrical Regulatory Framework, Licensing and Standards (AS/NZS 3000 and related)

Which of the following is a key requirement for electrical equipment installed in a damp location?

  1. It must be double insulated
  2. It must have an IP rating of at least IPX4 Correct answer.
  3. It must be protected by a 30 mA RCD
  4. It must be operated at reduced voltage

Explanation

In damp locations, electrical equipment must have a degree of protection of at least IPX4 to protect against splashing water. This is specified in AS/NZS 3000 to prevent moisture ingress.

Question 21Electrical Design, Load and Maximum Demand Calculations

In a single-phase 230 V installation, a resistive load draws 20 A. What is the apparent power drawn by the load?

  1. 9.2 kVA
  2. 1.15 kVA
  3. 2.3 kVA
  4. 4.6 kVA Correct answer.

Explanation

Apparent power for a single-phase circuit is the product of voltage and current, S = V × I. Here 230 V × 20 A = 4600 VA, or 4.6 kVA. Because the load is resistive, apparent power equals real power.

Question 22Electrical Design, Load and Maximum Demand Calculations

Which quantity is measured in volt-amperes rather than in watts?

  1. Real power
  2. Apparent power Correct answer.
  3. Reactive power
  4. Energy consumption

Explanation

Apparent power combines voltage and current without regard to phase angle and is expressed in volt-amperes (VA). Real power is expressed in watts and reactive power in volt-amperes reactive.

Question 23Electrical Design, Load and Maximum Demand Calculations

A load of 15 kW operates at a power factor of 0.75. What is its apparent power demand?

  1. 20 kVA Correct answer.
  2. 11.25 kVA
  3. 26.7 kVA
  4. 15 kVA

Explanation

Apparent power equals real power divided by power factor, S = P / pf. Thus 15 kW / 0.75 = 20 kVA. A power factor below unity always makes apparent power larger than real power.

Question 24Electrical Design, Load and Maximum Demand Calculations

What is the principal purpose of applying diversity (coincidence) factors in maximum demand calculations?

  1. To account for loads not operating simultaneously Correct answer.
  2. To correct for voltage drop in cables
  3. To increase the design current for safety
  4. To convert single-phase loads to three-phase

Explanation

Diversity factors recognise that not all connected loads draw their full rating at the same time. Applying them yields a realistic maximum demand rather than the arithmetic sum of all connected loads. They do not affect voltage drop directly or convert phase arrangements.

Question 25Electrical Design, Load and Maximum Demand Calculations

In a balanced three-phase circuit, the line current is 50 A at 400 V with a power factor of 0.8. What is the approximate real power?

  1. 40 kW
  2. 27.7 kW Correct answer.
  3. 48 kW
  4. 16 kW

Explanation

For a balanced three-phase load, P = √3 × V_L × I_L × pf. Substituting gives 1.732 × 400 × 50 × 0.8 ≈ 27.7 kW. The √3 factor is essential for three-phase calculations.

Question 26Electrical Design, Load and Maximum Demand Calculations

Per phase, a three-phase circuit carries 30 A at 230 V with a power factor of 0.9. What is the total three-phase real power?

  1. 18.6 kW Correct answer.
  2. 6.21 kW
  3. 10.35 kW
  4. 20.7 kW

Explanation

Using per-phase values, total power is P = 3 × V_ph × I_ph × pf. That is 3 × 230 × 30 × 0.9 = 18.6 kW. This is equivalent to the line-voltage formula √3 × 400 × 30 × 0.9.

Question 27Electrical Design, Load and Maximum Demand Calculations

A consumer has a connected load of 8 kW with an overall diversity factor of 0.6. What maximum demand should be used for design?

  1. 4.8 kW Correct answer.
  2. 8 kW
  3. 6.4 kW
  4. 13.3 kW

Explanation

Maximum demand is the connected load multiplied by the diversity factor: 8 kW × 0.6 = 4.8 kW. The result must always be less than or equal to the connected load.

Question 28Electrical Design, Load and Maximum Demand Calculations

Which statement correctly distinguishes maximum demand from connected load?

  1. Maximum demand is always larger than connected load
  2. Connected load is the greatest current ever drawn
  3. Maximum demand is the greatest demand expected over a period Correct answer.
  4. Connected load excludes diversity by definition

Explanation

Maximum demand is the greatest load expected to be drawn over a defined period, after diversity is applied. Connected load is the sum of all equipment ratings if operated simultaneously, so maximum demand is normally the smaller of the two.

Question 29Electrical Design, Load and Maximum Demand Calculations

An installation has the following single-phase loads on a 230 V supply: lighting 2 kW, socket outlets 3 kW, and a fixed appliance 1 kW. Applying no diversity, what is the total connected load current?

  1. 26.1 A Correct answer.
  2. 17.4 A
  3. 13.0 A
  4. 8.7 A

Explanation

Total connected load is 2 + 3 + 1 = 6 kW. Current equals power divided by voltage: 6000 W / 230 V ≈ 26.1 A. Diversity is deliberately not applied here.

Question 30Electrical Design, Load and Maximum Demand Calculations

A load draws 12 kW at a power factor of 0.6. What reactive power must be supplied to correct the power factor to unity?

  1. 9.6 kvar
  2. 12 kvar
  3. 16 kvar Correct answer.
  4. 7.2 kvar

Explanation

Initial apparent power is 12 / 0.6 = 20 kVA, so initial reactive power is √(20² − 12²) = 16 kvar. Correcting to unity requires cancelling all of this reactive power, so 16 kvar of capacitance is needed.

Question 31Electrical Design, Load and Maximum Demand Calculations

Why does improving power factor reduce the current drawn from the supply for the same real power?

  1. It increases the supply voltage
  2. It decreases the real power demand
  3. It lowers the cable resistance
  4. It reduces the apparent power required Correct answer.

Explanation

Current is proportional to apparent power for a given voltage. Raising the power factor brings apparent power closer to real power, so the current falls. Voltage, real power and cable resistance are not changed by power factor correction itself.

Question 32Electrical Design, Load and Maximum Demand Calculations

Which of the following is normally treated as a continuous load when determining maximum demand?

  1. A welder used intermittently
  2. Permanently connected space heating Correct answer.
  3. A portable drill
  4. A lift motor

Explanation

Continuous loads operate for sustained periods and are treated at their full rating in demand calculations. Intermittent or portable equipment is typically subject to diversity or demand factors.

Question 33Electrical Design, Load and Maximum Demand Calculations

A three-phase 400 V motor has a full-load current of 40 A and a power factor of 0.85. What is its input apparent power?

  1. 16 kVA
  2. 23.6 kVA
  3. 27.7 kVA Correct answer.
  4. 32.6 kVA

Explanation

Apparent power in a balanced three-phase circuit is S = √3 × V_L × I_L. That gives 1.732 × 400 × 40 ≈ 27.7 kVA. Power factor is not needed to find apparent power from voltage and current.

Question 34Electrical Design, Load and Maximum Demand Calculations

A dwelling has a total connected load of 24 kW and a maximum demand of 14.4 kW. What diversity factor has been applied?

  1. 0.6 Correct answer.
  2. 0.4
  3. 1.67
  4. 0.83

Explanation

Diversity factor equals maximum demand divided by connected load: 14.4 / 24 = 0.6. A factor below one reflects loads not operating simultaneously.

Question 35Electrical Design, Load and Maximum Demand Calculations

In maximum demand calculations, what does a demand factor express?

  1. The ratio of maximum demand to connected load Correct answer.
  2. The ratio of line to phase voltage
  3. The ratio of cable length to load
  4. The ratio of reactive to real power

Explanation

Demand factor is the ratio of the maximum demand to the total connected load. It reflects the extent to which the connected load is actually used at peak. It is not a power factor or a voltage ratio.

Question 36Electrical Design, Load and Maximum Demand Calculations

A single-phase 230 V circuit supplies a 3 kW water heater. What is the design current?

  1. 23.0 A
  2. 13.0 A Correct answer.
  3. 7.7 A
  4. 3.0 A

Explanation

Design current equals power divided by voltage for a resistive load: 3000 W / 230 V ≈ 13.0 A. This current is then used to select protective device and cable size.

Question 37Electrical Design, Load and Maximum Demand Calculations

A load has a real power of 8 kW and a reactive power of 6 kvar. What is its power factor?

  1. 0.6
  2. 1.33
  3. 0.8 Correct answer.
  4. 0.75

Explanation

Apparent power is √(8² + 6²) = 10 kVA. Power factor is real power divided by apparent power: 8 / 10 = 0.8. This follows directly from the power triangle.

Question 38Electrical Design, Load and Maximum Demand Calculations

Which factor most strongly determines the maximum demand of a group of domestic socket outlets?

  1. The length of the ring circuit
  2. The brand of protective device
  3. The number of outlets and their expected coincident use Correct answer.
  4. The colour of the socket faceplates

Explanation

Maximum demand for socket outlets depends on how many outlets exist and how many are likely to be used simultaneously. This is why diversity is applied to socket outlet loads rather than summing every outlet's rating.

Question 39Electrical Design, Load and Maximum Demand Calculations

A three-phase 400 V balanced load draws 60 A at a power factor of 0.9. What is the approximate real power in kW?

  1. 24.0 kW
  2. 21.6 kW
  3. 41.6 kW
  4. 37.4 kW Correct answer.

Explanation

P = √3 × V_L × I_L × pf = 1.732 × 400 × 60 × 0.9 ≈ 37.4 kW. All three factors, including the √3 and the power factor, must be applied together.

Question 40Electrical Design, Load and Maximum Demand Calculations

Why is it important to use the actual maximum demand rather than the connected load when sizing the main protective device?

  1. Maximum demand ignores diversity
  2. Using connected load guarantees a larger, safer device
  3. Connected load is always smaller
  4. Oversizing may prevent the device protecting against overload Correct answer.

Explanation

Sizing the main device for the full connected load can result in a rating too large to protect the supply conductors against overload. The device should be based on a realistic maximum demand, coordinated with cable capacity.

Question 41Electrical Design, Load and Maximum Demand Calculations

A 5 kW load operates at a power factor of 0.5. What current does it draw from a 230 V single-phase supply?

  1. 21.7 A
  2. 43.5 A Correct answer.
  3. 10.9 A
  4. 65.2 A

Explanation

Apparent power is 5 / 0.5 = 10 kVA, and current is apparent power divided by voltage: 10000 / 230 ≈ 43.5 A. Using the real power alone would underestimate the current.

Question 42Electrical Design, Load and Maximum Demand Calculations

A group of loads has individual maximum demands that do not all peak together. Which approach gives the most realistic group maximum demand?

  1. Use the largest single load only
  2. Apply a group diversity factor to the sum Correct answer.
  3. Average the individual maximum demands
  4. Sum every individual maximum demand

Explanation

Applying a group diversity factor to the sum of individual maximum demands accounts for the fact that loads peak at different times. Simply summing individual maxima tends to overstate the group demand.

Question 43Electrical Design, Load and Maximum Demand Calculations

A 400 V three-phase motor takes 25 A per phase at a power factor of 0.8. What reactive power does it draw?

  1. 13.9 kvar Correct answer.
  2. 8.0 kvar
  3. 17.3 kvar
  4. 10.4 kvar

Explanation

Apparent power is √3 × 400 × 25 ≈ 17.3 kVA, and real power is 17.3 × 0.8 ≈ 13.9 kW. Reactive power is √(17.3² − 13.9²) ≈ 10.4 kvar, or equivalently S × sin φ.

Question 44Electrical Design, Load and Maximum Demand Calculations

Which statement about the relationship between power factor and apparent power for a fixed real power is correct?

  1. Apparent power rises as power factor rises toward unity
  2. Apparent power is independent of power factor
  3. Apparent power falls as power factor rises toward unity Correct answer.
  4. Apparent power equals real power at all power factors

Explanation

Since S = P / pf, for a fixed real power a power factor closer to unity gives apparent power closer to real power, so apparent power falls. Unity power factor gives the minimum possible apparent power.

Question 45Earthing, Protective Bonding and Fault Loop Impedance

Under the AS/NZS 3000 framework, what is the primary purpose of equipotential bonding of conductive building parts?

  1. To increase the fault loop impedance to reduce fault current
  2. To limit potential differences between simultaneously accessible conductive parts Correct answer.
  3. To provide a low-resistance path for operating current during normal service
  4. To replace the need for a protective earthing conductor

Explanation

Equipotential bonding keeps simultaneously accessible conductive parts at substantially the same potential so that touch voltages during a fault remain at safe levels. It does not carry normal operating current and does not replace the protective earthing conductor.

Question 46Earthing, Protective Bonding and Fault Loop Impedance

What does the term 'fault loop impedance' describe in an installation?

  1. The insulation resistance between active and neutral
  2. The impedance of the total path taken by fault current from the source and back to it Correct answer.
  3. The resistance of the earth electrode alone
  4. The impedance of the load connected at the socket outlet

Explanation

Fault loop impedance is the impedance of the complete circuit that fault current follows, including the source, the active conductor, the fault, the protective earthing path and the return to the supply transformer. It determines the magnitude of fault current and hence disconnection time.

Question 47Earthing, Protective Bonding and Fault Loop Impedance

Which conductor connects the exposed conductive parts of equipment to the earthing system?

  1. The protective earthing conductor Correct answer.
  2. The equipotential bonding conductor between extraneous parts
  3. The neutral conductor
  4. The active conductor

Explanation

The protective earthing conductor links exposed conductive parts to the earthing system so fault current can return and operate the protective device. Neutral and active conductors carry operating current, and bonding conductors join extraneous conductive parts.

Question 48Earthing, Protective Bonding and Fault Loop Impedance

An earth electrode is installed to provide a connection to earth. Which property most directly governs its effectiveness?

  1. The rated current of the main switch
  2. The colour of the insulation on its connecting conductor
  3. The resistance between the electrode and the general mass of earth Correct answer.
  4. The cross-sectional area of the active conductor supplying the installation

Explanation

The effectiveness of an earth electrode is measured by its resistance to the general mass of earth; lower resistance improves fault current return and voltage control. Insulation colour, active conductor size and switch rating do not determine electrode effectiveness.

Question 49Earthing, Protective Bonding and Fault Loop Impedance

In a MEN (multiple earthed neutral) system, where is the neutral connected to earth?

  1. At every light fitting
  2. At the supply transformer and at the main earthing terminal of each installation Correct answer.
  3. Only at the earth electrode of the installation
  4. Only at the furthest socket outlet

Explanation

In an MEN system the neutral is earthed at the supply source and again at the main earthing terminal of each installation, creating the multiple earth references. This arrangement supports low fault loop impedance and effective protective device operation.

Question 50Earthing, Protective Bonding and Fault Loop Impedance

What is the main risk if the main equipotential bonding conductor to a metallic water service is disconnected?

  1. The protective device will trip during normal operation
  2. The water service will carry normal load current continuously
  3. The fault loop impedance will fall to zero
  4. A dangerous potential difference may appear between the pipe and other earthed metal during a fault Correct answer.

Explanation

Without bonding, a fault or stray current can raise the potential of the metallic service relative to surrounding earthed metal, creating a shock hazard. Bonding does not carry normal load current and does not reduce loop impedance to zero.