Free mock exam
Protection Coordination — Level 3 Systems Design Practice
Free topic-focused mock exam: all 30 questions on Protection Coordination, drawn from the wider Level 3 Systems Design bank. 35-minute timer, 70% to pass, worked explanation on every question. Use this when you've taken the full mock once and want to drill the topics you got wrong.
- Questions
- 30
- Time limit
- 35 min
- Pass mark
- 70% · 21/30
- Question bank
- 30
Free, no sign-up. Retake as many times as you like — the questions are reshuffled, with the answer order changed.
Sample questions
01Protection coordination (discrimination) means:
- Ano device operates until the fault current falls to a safe level
- Bonly the device nearest the fault operates, leaving other circuits unaffected
- Cthe main switch always operates first, isolating the whole installation
- Dall upstream devices operate together so the fault is cleared quickly
Why: Discrimination ensures the protective device nearest the fault operates first, maintaining supply elsewhere.
02Back-up protection occurs when:
- Atwo devices always operate simultaneously
- Bthe supply is disconnected before any device operates
- Cthe downstream device protects the upstream device
- Dan upstream device clears a fault if the closer device fails to operate
Why: Back-up protection provides secondary protection if the primary device fails to operate.
03Time-current characteristics of protective devices are important for:
- Aunderstanding how devices respond at different fault-current levels
- Bconfirming that the rated current is at least the design current
- Cestimating the connected lighting load of the building being designed
- Dcalculating the nominal supply voltage at the origin of the circuit
Why: Time-current curves show the operating time at different current levels, which is essential for coordination.
Common questions
Is the Protection Coordination mock exam free?
Yes — 100% free, no sign-up needed. Questions are pulled at random from a substantial bank, with a worked explanation on every question after you submit.
Can I retake the mock exam?
Yes. Every attempt picks a different random selection and reshuffles the options, so each retake gives you genuinely new questions. No limit on retakes.
Does this count towards the real qualification?
No — this is independent practice material. To gain the actual qualification you need to sit the official assessment through an approved provider.
