CSCS Excavations & Confined Spaces Questions
Trench support, inspections and confined-space entry.
Excavations & Confined Spaces — practice questions (untimed, instant feedback)
- 7 questions · pass mark 90%
- Untimed practice — you see the correct answer immediately after each question.
- Some questions need more than one answer — these are clearly marked.
All 7 Excavations & Confined Spaces questions and answers
These are the same 7 questions as the practice test above, written out with the correct answer and the reasoning behind it. Read them through when you want to revise rather than test yourself.
1. You see the side supports move while you are working in an excavation. What should you do?
Answer: Get yourself and everyone else out quickly
- A) Nothing — the sides always move a little
- B) Watch to see whether they shift again
- C) Get yourself and everyone else out quickly (correct answer)
- D) Move to another part of the trench
Why: Moving supports warn of collapse — get everyone out of the excavation at once.
2. The gas alarm sounds while you are in a confined space. What should you do?
Answer: Leave the confined space straight away
- A) Keep working but avoid electrical tools
- B) Keep working but take fresh-air breaks
- C) Leave the confined space straight away (correct answer)
- D) Turn the alarm off
Why: A gas alarm means leave the confined space immediately.
3. What is the recommended way to protect the edge of an excavation?
Answer: Install a barrier
- A) Put up a warning sign
- B) Install a barrier (correct answer)
- C) Tell people verbally
- D) Place cones around it
Why: A physical barrier stops people and vehicles falling into the excavation.
4. What is the main hazard of a confined space?
Answer: Limited access and escape
- A) Limited access and escape (correct answer)
- B) High ceilings
- C) Good ventilation
- D) Clear visibility
Why: Restricted entry and exit make escape and rescue difficult in a confined space.
5. Who manages the risks of excavation work on site?
Answer: The site manager
- A) The site manager (correct answer)
- B) The first aider
- C) Only the digger driver
- D) Nobody in particular
Why: The site manager is responsible for managing site risks, including excavations.
6. How often should the air in a confined space be tested?
Answer: Before each entry
- A) Once a day
- B) Once per shift
- C) Before each entry (correct answer)
- D) Only if a problem is reported
Why: Test the atmosphere before every entry to confirm it is safe.
7. What does 'shoring' mean in excavation safety?
Answer: Supporting the sides to prevent collapse
- A) Removing water
- B) Shielding from debris
- C) Supporting the sides to prevent collapse (correct answer)
- D) Building a temporary walkway
Why: Shoring supports the trench sides to prevent a collapse.
What this topic covers in the CSCS test
These two subjects sit together because they fail the same way, fast and with almost no warning. An unsupported trench side can bury you in seconds, and the air in a confined space can be lethal before you notice anything is wrong. Two HSE points are worth carrying into the exam: no ground can be relied upon to stand unsupported, and the people killed in confined spaces include those who went in to rescue someone else.
- Why excavations collapse, and how shoring, trench boxes and battering prevent it
- Who inspects an excavation, when, and what must be recorded
- Edge protection, spoil heaps, and keeping plant back from the edge
- Safe access and egress, and why petrol and diesel engines are kept out
- Buried services: plans, cable locating devices and safe digging practice
- What makes a space a confined space, and the risks that define one
- The Confined Spaces Regulations 1997: atmosphere testing, ventilation, permits and rescue
Key facts worth memorising
- A cubic metre of soil can weigh over 1.5 tonnes
- That is why a collapse is so often fatal even in a shallow trench, and why HSE says no ground can be relied upon to stand unsupported in all circumstances.
- Inspection at the start of every shift
- Regulation 22 of CDM 2015 requires a competent person to inspect a supported or battered excavation at the start of the shift, after any event likely to affect its stability, and after any fall of material.
- A written report within 24 hours
- Under regulation 24 of CDM 2015, an inspector who is not satisfied must say so before the end of the shift and provide a written report within 24 hours.
- Ladders reach 1 metre above the landing
- A ladder used for access must stand on a firm level base, be secured against slipping and extend at least 1 metre above the landing place unless there is a suitable alternative handhold.
- Locate, mark, then dig carefully
- HSE's sequence is plans first, then a locating device used frequently and repeatedly, then trial holes by hand, digging alongside the service rather than above it and using insulated tools near cables.
- A confined space is defined by risk, not size
- It is a space that is enclosed or largely enclosed with a foreseeable risk of fire, explosion, loss of consciousness, asphyxiation or drowning, so a large silo counts and so does an unventilated pit.
What people get wrong
A shallow trench does not need support.
Depth is not the test. With a cubic metre of soil weighing over 1.5 tonnes it takes very little material to crush someone. Decide the support before you dig and have it on site before work starts.
If a workmate goes down in a confined space, you get them out.
This is how confined spaces kill more than one person at a time. HSE says the dead include untrained rescuers, and that relying on the emergency services is not enough. Raise the alarm and use the rescue arrangements that had to exist before the work began.
The service drawings show you where the cables are.
Plans give only an indication of the location and number of buried services, and HSE says tracing with a locating device afterwards is essential. Marker tape works the same way: it tells you something is close, not exactly where.
One gas test at the start covers you for the day.
HSE warns that a confined space being safe one day does not mean it always will be. Test before entry and keep monitoring, and if the alarm sounds you leave first and work out why afterwards. Never try to sweeten the air with oxygen, which sharply raises the fire risk.
Answering these questions in the test
Almost every scenario here has one answer that means getting out or staying out, and that is the one to take. Supports moving, a gas alarm sounding, an odd smell, a colleague collapsing: none of these are assessed from the inside. Also watch the difference between a warning and a control. Marker tape, a gas alarm and a lookout all tell you something. What keeps you alive is the trench support, the tested atmosphere, the barrier at the edge and the rescue plan made before anyone went in.
Sources
Written from the following. Where a figure could not be verified against one of these, it has been left out rather than approximated — our sources and methodology explains how we date and re-check them. Spotted something wrong? Report an error and we will fix it.
- hse.gov.uk/construction/safetytopics/excavations.htm
- hse.gov.uk/construction/safetytopics/underground.htm
- legislation.gov.uk/uksi/2015/51/regulation/22/made
- legislation.gov.uk/uksi/2015/51/regulation/24/made
- hse.gov.uk/confinedspace/introduction.htm
- hse.gov.uk/confinedspace/legislation.htm
- hse.gov.uk/pubns/indg258.pdf
- legislation.gov.uk/uksi/1997/1713/contents/made
Topics that come up alongside excavations & confined spaces
Ready for the real thing?
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