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Try Arc free: a video and 5 questions
This is the same content you get in the app. Watch the free RCD video, then have a go at the questions.
How to wire an RCD · 🇦🇺 Australia
3:46 · AS/NZS 3000:2018
How to wire an RCD · 🇮🇪 Ireland
4:29 · I.S. 10101
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5 sample questions
Question 1
Ohm's law relates voltage (V), current (I) and resistance (R). Which formula is correct?
- V = I × R
- V = I / R
- V = I + R
- V = R / I
Show answer
Voltage equals current times resistance. Rearrange as I = V/R or R = V/I when needed.
Question 2
A 230 V heater draws 10 A. What is its resistance (approx.)?
- 23 Ω
- 2.3 Ω
- 230 Ω
- 0.23 Ω
Show answer
R = V/I = 230/10 = 23 Ω.
Question 3
The safest basic isolation sequence is:
- Identify → isolate → lock/secure → test before touch → proceed
- Test while live → then maybe switch off
- Cut the earth first
- Remove fuses under load without PPE planning
Show answer
Safe work centres on positive isolation and proving dead at the point of work.
Question 4
Which is the correct general order for mandatory installation tests after isolation/visual checks?
- Earthing continuity → insulation resistance → polarity → correct circuit connections → earth fault loop impedance → RCD operation
- RCD first → then energise → then insulation
- Polarity → RCD → insulation → earthing
- Insulation → RCD → polarity → earthing
Show answer
A common teaching sequence is: continuity of earthing, insulation resistance, polarity, correct circuit connections, earth fault loop impedance, then RCD tests. Confirm against your current AS/NZS testing standard and RTO materials.
Question 5
A 40 Ω heating element is connected to 230 V. What current does it draw?
- 9.20 A
- 0.17 A
- 11.50 A
- 5.75 A
Show answer
Ohm's law: I = V ÷ R → I = 230 ÷ 40 → I = 5.75 A
Original practice wording, not from official exam papers.
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