What is the legal definition of a confined space under UK regulations?

Under the Confined Spaces Regulations 1997, a confined space is defined as any place which is substantially (though not always entirely) enclosed, and where serious injury can occur from hazardous substances or conditions within the space, or nearby. It is the risk, not just the size, that defines a confined space.

Any space that is fully sealed and located below ground level with no natural ventilation

Any enclosed space where there is a reasonably foreseeable risk of serious injury from hazardous substances or conditions

Any work area smaller than 2 metres in height where a person cannot stand fully upright

Any room without a permanent means of mechanical ventilation or air conditioning

Which of the following is a key characteristic of a confined space?

A confined space has two key characteristics: it is substantially (though not always entirely) enclosed, and there is a reasonably foreseeable risk of serious injury from hazardous substances or conditions. A space does not need to be underground, sealed, or unlit to be classified as confined.

It must be completely sealed with no openings to the outside atmosphere

It must be smaller than the minimum dimensions specified in the regulations

It must be substantially enclosed and have a reasonably foreseeable risk of serious injury

It must be situated underground or below the surrounding ground level

Which of the following is an example of a confined space?

A storage tank that previously held chemicals is a classic example of a confined space. It is substantially enclosed, has limited access and egress, and there is a foreseeable risk of serious injury from residual hazardous substances, oxygen depletion, or a build-up of flammable vapours.

A workshop fitted with extract ventilation and multiple windows

An office with permanent mechanical ventilation and two exits

An open-top skip in a well-ventilated yard

A storage tank that previously held chemicals

Free mock exam

Understanding Confined Spaces — Confined Spaces Practice

Free topic-focused mock exam: 15 random questions from a pool of 40 on Understanding Confined Spaces, drawn from the wider Confined Spaces bank. 20-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: 15
Time limit: 20
Pass mark: 70%
Bank size: 40

Free · no sign-up · timer can be ignored · retake as many times as you want

Sample questions

01What is the legal definition of a confined space under UK regulations?
- A.Any room without a permanent means of mechanical ventilation or air conditioning
- B.Any enclosed space where there is a reasonably foreseeable risk of serious injury from hazardous substances or conditions
- C.Any space that is fully sealed and located below ground level with no natural ventilation
- D.Any work area smaller than 2 metres in height where a person cannot stand fully upright
Why: Under the Confined Spaces Regulations 1997, a confined space is defined as any place which is substantially (though not always entirely) enclosed, and where serious injury can occur from hazardous substances or conditions within the space, or nearby. It is the risk, not just the size, that defines a confined space.
02Which of the following is a key characteristic of a confined space?
- A.It must be smaller than the minimum dimensions specified in the regulations
- B.It must be situated underground or below the surrounding ground level
- C.It must be completely sealed with no openings to the outside atmosphere
- D.It must be substantially enclosed and have a reasonably foreseeable risk of serious injury
Why: A confined space has two key characteristics: it is substantially (though not always entirely) enclosed, and there is a reasonably foreseeable risk of serious injury from hazardous substances or conditions. A space does not need to be underground, sealed, or unlit to be classified as confined.
03Which of the following is an example of a confined space?
- A.An office with permanent mechanical ventilation and two exits
- B.A storage tank that previously held chemicals
- C.A workshop fitted with extract ventilation and multiple windows
- D.An open-top skip in a well-ventilated yard
Why: A storage tank that previously held chemicals is a classic example of a confined space. It is substantially enclosed, has limited access and egress, and there is a foreseeable risk of serious injury from residual hazardous substances, oxygen depletion, or a build-up of flammable vapours.

FAQ

Is the Understanding Confined Spaces 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.