Gas ACS Practice — CCN1 Mock Tests & Revision Questions

CCN1 · Core Domestic Gas Safety

Pass your gas ACS assessments with confidence

Realistic mock tests and hundreds of practice questions covering CCN1 core gas safety — legislation, combustion, ventilation, tightness testing, flues, gas rates and unsafe situations. Timed like the real thing, with a clear explanation for every answer.

Questions: 40
Minutes: 60
Pass mark: 80%

Pass readiness · target 80%

See pricing

Hundreds of exam-style questions
An explanation for every answer
Realistic 60-minute timed mocks
Marked to the 80% pass standard
Works offline on your phone
Cancel anytime

01 Get started

Start practising in seconds

No setup, no faff. Pick your assessment below and sit a timed mock or drill questions at your own pace — your first questions are free, no card needed.

02 Why Gas ACS Pass

Built for the way gas engineers actually revise

On the van, between jobs, the night before the assessment. Everything here is tuned to get you over the 80% line — and to make the knowledge stick.

Marked like the real assessment

Every mock is 40 questions on a 60-minute clock, graded against the 80% ACS pass mark — so you know you're ready before you sit the real thing.

An explanation for every answer

Never just "wrong". Each question ties the correct answer back to the standard behind it — GSIUR, BS 6891, the GIUSP — so it stays learned.

Know your weak spots

Per-topic scoring across combustion, ventilation, tightness testing, flues and unsafe situations shows exactly what to revise next.

Revise anywhere, even offline

Installs to your phone and works on-site with no signal. Ten spare minutes between jobs is ten minutes of revision.

03 How it works

Three steps to assessment-ready

1
Pick a mock or a practice set

Sit a full 40-question paper under exam conditions, or drill a single topic at your own pace with instant feedback.
2
Answer, then learn

Work through realistic CCN1 questions. In practice mode, every answer is explained the moment you commit to it.
3
Track your readiness

Your dashboard blends recent scores with topic mastery into a single pass-readiness figure. Drill your weak spots until it's green.

04 See the real thing

A genuine CCN1-style question

This is exactly the quality you'll practise with — on-topic, to the standard, and explained. Here's one from the combustion module, on the house.

Correct answer shown · explanation included, just like the app.

Combustion · Sample Free

A flue-gas analyser reports the ratio of carbon monoxide to carbon dioxide (CO/CO₂) in an appliance's combustion products. What is the maximum ratio for a safe, correctly-operating domestic gas appliance?

A0.02

B0.004Correct

C0.04

D0.0004

Why A CO/CO₂ ratio at or below 0.004 indicates clean, complete combustion. A higher ratio points to incomplete combustion and a potential carbon-monoxide hazard.

40Questions / mock

60Minutes / paper

80%Mark to pass

7+Core topics

05 Pricing

One plan. Everything you need to pass.

Start free — your first questions are on us, no card needed. Unlock the full bank when you're ready.

Gas ACS Pass · Premium

£9.99/month

Cancel anytime — no contract, no cancellation fee.

Every mock paper and practice question
The searchable Question Bank — every answer explained
Weak-topic analytics and your pass-readiness dashboard
"Drill my weak spots" adaptive practice
Installs and works offline on your phone

Or first.

06 FAQ

Straight answers before you start

What is the gas ACS CCN1 assessment?

CCN1 is the core domestic gas safety assessment within the ACS (Accredited Certification Scheme). It's the foundation module most domestic gas qualifications build on, covering the safe handling of gas from the meter through to the appliance.

How many questions are in a mock, and what's the pass mark?

Each mock paper mirrors assessment conditions: 40 questions, a 60-minute countdown, marked against the 80% pass standard. Practice mode is untimed with feedback after every question.

Is Gas ACS Pass official or affiliated with Gas Safe?

No. We're an independent revision aid — not affiliated with or endorsed by the Gas Safe Register or any awarding body. Always study the current official materials alongside this tool; it doesn't replace formal ACS training or assessment.

Are these the real exam questions?

No — every question is original, written to the style and standard of the real assessment and based on published UK gas safety guidance. They're built for revision, not a leaked paper.

How does billing work?

One simple subscription at £9.99/month. Cancel anytime from your account — no contract and no cancellation fee. You can try the free questions before you subscribe.

Can I use it on site without signal?

Yes. Install it to your phone's home screen and it works offline, so you can revise between jobs even with no connection.

Walk in ready. Walk out qualified.

Sit your first timed mock in the next five minutes — free to start, marked the moment you finish.

Ready for assessment day?

Sit a full Mock Test under real conditions — 40 questions, a 60-minute timer, marked against the 80% pass standard. Or use Practice mode to work through questions at your own pace with instant feedback and explanations.

Mock tests

Question Bank

Every question with its correct answer and explanation. Search by keyword — it looks through questions and answers.

Mock Tests

Each mock is a full paper sat under real conditions: 40 questions, a 60-minute countdown, and the 80% pass mark. Pick a test to begin.

✔ Every answer comes with an explanation and the topic to revise.

Practice Session

Question bank Number of questions Practice is untimed with instant feedback and explanations after each question.

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