Apprentice revision

Capstone and licence exam practice

Unlimited practice calculations for the capstone and licence assessments: voltage drop, maximum demand, earth conductor sizing and three-phase current. Every question has new numbers, marks your answer, and shows the full working so you can see where you went wrong. Free, no login, nothing saved.

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Voltage drop

A three-phase 400 V circuit runs 40 m in 4 mm² copper and carries 20 A. Take Vc = 9.6 mV/A·m for this cable and circuit type. What is the voltage drop?

Supply: 400 V three phase
Run length (L): 40 m
Current (I): 20 A
Vc: 9.6 mV/A·m

What the capstone tests

In Australia the capstone is the final core unit of the Certificate III in Electrotechnology Electrician (UEE30820): UEEEL0039, Design, install and verify compliance and functionality of general electrical installations. Your training provider runs it. The calculation side covers:

maximum demand for the installation, mains and submains;
cable selection for mains, submains and final subcircuits, including derating;
voltage drop against the 5 percent allowance;
earth fault loop impedance limits and disconnection times;
sizing active and protective earthing conductors;
verification testing of the finished installation.

The practice above covers the four that reduce to a clean calculation. Cable current ratings are left out on purpose: they come straight from the AS/NZS 3008.1.1 tables, and practising them properly means using your own copy of the book, which is what you will do on the day. Use the cable sizing calculator to check your working once you have done it by hand.

Worked examples

One of each type, worked through the way an assessor wants to see it: formula first, then the numbers, then the answer with units.

Voltage drop

A three-phase 400 V circuit runs 30 m in 10 mm² copper and carries 29 A. Take Vc = 3.8 mV/A·m for this cable and circuit type. What is the voltage drop?

Vd = L x I x Vc / 1000 (Vc already includes the factor for the circuit type)
Vd = 30 x 29 x 3.8 / 1000 = 3.31 V
As a percentage of 400 V: 3.31 / 400 x 100 = 0.83 %
Against a 5 % allowance (20.0 V) this passes on its own. Remember the 5 % covers the whole installation from the point of supply, so the drop on the mains and submains comes out of the same allowance.

Answer: 3.31 V (AS/NZS 3008.1.1 voltage drop method; AS/NZS 3000 Clause 3.6.2 (5 percent))

Maximum demand, single domestic

A single domestic installation on a 230 V single-phase supply has 15 lighting points, 16 10 A socket outlet points, a 12 kW range, a 3.6 kW storage water heater. Using the Table C1 load groups for a single domestic installation, what is the maximum demand?

Convert kW ratings to amps at 230 V: I = P x 1000 / 230
Lighting points: 15 points: 3 A for the first 20 = 3 A
10 A socket outlet points: 16 points: 10 A for the first 20 = 10 A
Electric range: 52.2 A connected x 50% = 26.1 A
Storage water heater: 15.7 A at full load current
Maximum demand = 54.8 A

Answer: 54.8 A (AS/NZS 3000:2018 Appendix C, Table C1 (single domestic electrical installation))

Earth conductor size

A circuit is wired in 150 mm² copper active conductors. Using AS/NZS 3000 Table 5.1 for copper actives, what is the minimum size of the copper protective earthing conductor?

Table 5.1, copper active conductors column: 150 mm² active requires at least 50 mm² copper earth.
Table 5.1 is the minimum. A larger earth may be needed to meet earth fault loop impedance and disconnection times, so check those as well.

Answer: 50 mm² (AS/NZS 3000:2018 Table 5.1)

Three-phase line current

A balanced three-phase load draws 37 kW at 0.86 power factor from a 400 V supply. What is the line current?

I = P / (√3 x VL x cos φ)
I = 37000 / (1.732 x 400 x 0.86) = 37000 / 595.8 = 62.1 A
For a motor, use the nameplate output and efficiency as well: input power = output power / efficiency.

Answer: 62.1 A (Three-phase power: P = √3 x VL x IL x cos φ)

How licensing works in each state

The capstone or final assessment gets you the qualification; the licence or registration comes from your state regulator. Requirements, forms and fees change, so check with your training provider and the regulator linked below before you apply.

Where	Final assessment	Licence or registration	Regulator
New South Wales	UEEEL0039 capstone through your training provider	Qualified Supervisor Certificate (Electrician)	NSW Fair Trading
Victoria	Licensed Electrician Assessment (LEA): theory, safe working practice and practical	Electrician licence (A Grade)	Energy Safe Victoria
Queensland	UEEEL0039 capstone through your training provider	Electrical mechanic licence	Electrical Safety Office
South Australia	Completed apprenticeship and Certificate III	Electrical worker registration	Consumer and Business Services
Western Australia	UEEEL0039 capstone through your training provider	Electrician's licence	Building and Energy, Electrical Licensing Board
Tasmania	Approved course and completed apprenticeship	Electrical practitioner licence (Electrician)	Consumer, Building and Occupational Services
Australian Capital Territory	Capstone through your training provider	Electrician licence (unrestricted)	Access Canberra
Northern Territory	Completed apprenticeship, with a capstone block through your training provider	Unrestricted electrical work licence	NT WorkSafe, Electrical Safety Regulator
New Zealand	Electricians Theory and Regulations exams, plus the practical assessment where required	Registration (Electrician) and practising licence	Electrical Workers Registration Board

The training package for electrical qualifications is under review, so unit codes may change. In New Zealand, cable sizing uses AS/NZS 3008.1.2, the New Zealand part of the cable selection standard.

More revision

Knowledge Assessment 5 practice quiz, 47 questions on design factors, protection, installation and equipment.
Maximum demand guide and the Table C1 load schedule calculator.
Voltage drop explained, including the single-phase factor of two that catches people out.
Earth conductor calculator for Table 5.1 and the adiabatic check.

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Frequently asked questions

What is the electrical capstone assessment?

In Australia the capstone is the final unit of the Certificate III in Electrotechnology Electrician (UEE30820), UEEEL0039 Design, install and verify compliance and functionality of general electrical installations. It is assessed by your training provider and tests design calculations, installation and verification testing. Victoria also has the Licensed Electrician Assessment (LEA) run through Energy Safe Victoria approved providers.

What calculations come up in the capstone?

The capstone unit covers maximum demand, cable selection for mains, submains and final subcircuits, voltage drop, earth fault loop impedance limits, sizing active and protective earth conductors, and verification testing. Practise each one until you can do it from the standard without help.

Are these practice answers the same as the real tables?

Earth conductor questions use AS/NZS 3000 Table 5.1 and maximum demand questions use the Table C1 load groups, both checked against the standard. Voltage drop questions give you the cable Vc value as data, so the answer depends only on the method. In the real assessment you will look the Vc up in AS/NZS 3008.1.1 yourself.

How is New Zealand different?

New Zealand electricians register with the Electrical Workers Registration Board rather than doing a capstone unit. The pathway includes the Electricians Theory and Electricians Regulations exams. Cable sizing in New Zealand uses AS/NZS 3008.1.2, the New Zealand part of the cable selection standard.