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Excavations and confined spaces questions for the CSCS test

7 free questions on Excavations and confined spaces, from section C. Safety. Every question is original and explains why each option is right or wrong.

Last verified against HSE guidance and the law ·How we write our questions

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Question 1

Easier ·Link to this question (question 1)

You are about to start work in a trench that has supports along its sides.

When must a competent person inspect the trench supports?

Choose one answer.

  1. A. Each shift, and after anything that affects them
  2. B. Once, when the trench is first dug
  3. C. Once a week, on the same day each week
  4. D. Only if someone notices a crack in the ground nearby
Show the answer and explanation

Answer: A

  • A. Right: Right. HSE says supports or battering must be inspected at the start of each shift and after any event that could affect their strength, such as heavy rain or a fall of material.
  • B. Wrong: Wrong. Ground conditions change. One check when the trench is dug is not enough.
  • C. Wrong: Wrong. Weekly is not often enough. Trench supports are checked at the start of every shift.
  • D. Wrong: Wrong. A collapse can happen with no obvious warning. Inspections must be regular, not only when someone sees a problem.

Explanation

Excavations must be inspected by a competent person at the start of each shift and after any event that could affect their stability. No work until it is safe.

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Question 2

Medium · choose 2 ·Link to this question (question 2)

Your gang is digging a deep trench for a new drain.

Which two help stop the sides collapsing? (Choose two.)

Choose two answers.

  1. A. Getting the work done quickly so the trench is open for less time
  2. B. Supporting the sides, or sloping them back to a safe angle
  3. C. Keeping plant, vehicles and spoil heaps back from the edge
  4. D. Leaving the sides unsupported if the ground is dry and hard
Show the answer and explanation

Answers: B, C

  • A. Wrong: Wrong. A trench can collapse at any time, however quickly you work. It needs proper support.
  • B. Right: Right. Supports or battering (sloping the sides back) should be planned before digging starts.
  • C. Right: Right. Extra weight near the edge makes a collapse more likely, and spoil can fall into the trench.
  • D. Wrong: Wrong. HSE says no ground can be relied on to stand unsupported in all conditions.

Explanation

Support or batter the sides of excavations, and keep plant, vehicles and spoil back from the edge.

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Question 3

Medium ·Link to this question (question 3)

A workmate has gone down into a sewer manhole and collapsed at the bottom. They are not answering you.

What should you do?

Choose one answer.

  1. A. Hold your breath, climb down and bring them up
  2. B. Wait and see if they come round before doing anything
  3. C. Stay out, raise the alarm, follow the emergency plan
  4. D. Climb down straight away to pull them out
Show the answer and explanation

Answer: C

  • A. Wrong: Wrong. You can't hold your breath long enough to do a rescue, and some gases act very quickly.
  • B. Wrong: Wrong. Every second counts. Raise the alarm straight away so the trained rescue team can act.
  • C. Right: Right. Whatever made your workmate collapse, such as bad air or no oxygen, could overcome you too. People have died trying to rescue others from confined spaces.
  • D. Wrong: Wrong. Without the right equipment and training you are likely to be overcome as well, and then there are two people to rescue.

Explanation

Never go into a confined space to rescue someone unless you are trained and equipped to do so. Raise the alarm and follow the site's emergency arrangements.

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Question 4

Medium ·Link to this question (question 4)

Your gang is about to dig a trench near a road, where there may be buried electricity cables.

Put these steps in order, starting with the first.

Put these 4 steps in order.

  1. A. Trace the cables with a locator and mark them
  2. B. Dig trial holes by hand to confirm where they are
  3. C. Dig the trench, using the locator again as you go
  4. D. Get and check the plans of buried services
Show the answer and explanation

Correct order: D, A, B, C

  1. D. Get and check the plans of buried services First. Plans show roughly where services are, but they are only a guide.
  2. A. Trace the cables with a locator and mark them Second. Use a cable locator to find and mark the cables on the ground.
  3. B. Dig trial holes by hand to confirm where they are Third. Hand-dig carefully, with suitable tools, to expose the cables and confirm their position.
  4. C. Dig the trench, using the locator again as you go Last. Keep using the locator often during the work, as cables are not always where they seem.

Explanation

Before digging: check the plans, trace and mark cables with a locator, then confirm with hand-dug trial holes. Keep using the locator as you dig.

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Question 5

Easier ·Link to this question (question 5)

A deep trench runs next to a footpath that workers use to get to the canteen.

What should be along the edge of the trench?

Choose one answer.

  1. A. A line of traffic cones
  2. B. A sign asking people to be careful
  3. C. Nothing, as people can see the trench
  4. D. Substantial barriers
Show the answer and explanation

Answer: D

  • A. Wrong: Wrong. Cones mark an area, but they won't stop someone falling into a trench.
  • B. Wrong: Wrong. A sign alone won't stop someone falling in, especially in poor light.
  • C. Wrong: Wrong. People can trip, slip or not notice the edge. Barriers are needed.
  • D. Right: Right. HSE says excavation edges should be protected with substantial barriers where people could fall into them.

Explanation

Put substantial barriers along excavation edges where people could fall in, and keep spoil and plant back from the edge.

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Question 6

Medium ·Link to this question (question 6)

You are hand-digging a trial hole to expose a buried electricity cable that has been located.

What tools should you use?

Choose one answer.

  1. A. Insulated hand tools, digging carefully
  2. B. A pick, so you get through the ground faster
  3. C. A breaker, as the ground is hard
  4. D. The excavator bucket, going slowly
Show the answer and explanation

Answer: A

  • A. Right: Right. HSE says insulated tools should be used when hand digging near electric cables, and trial holes are dug with suitable hand tools.
  • B. Wrong: Wrong. A pick can easily damage a cable. Dig carefully with suitable insulated tools.
  • C. Wrong: Wrong. A breaker could strike the cable. Hand dig with insulated tools.
  • D. Wrong: Wrong. Machines can easily damage cables. Trial holes near cables are dug by hand.

Explanation

Near buried cables, dig by hand with insulated tools. Use the cable locator often as you go.

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Question 7

Medium ·Link to this question (question 7)

A valve inside an underground chamber needs adjusting. It could be done from outside using a long-handled tool.

What does HSE say?

Choose one answer.

  1. A. Send in the newest worker so others are safe
  2. B. Do it from outside if possible
  3. C. Climb in, as it will be quicker
  4. D. Climb in, but only for a few minutes
Show the answer and explanation

Answer: B

  • A. Wrong: Wrong. Nobody should go in if it isn't needed, and anyone who does must be trained and equipped.
  • B. Right: Right. HSE says wherever possible avoid working in confined spaces. Don't go in unless it is essential.
  • C. Wrong: Wrong. A confined space can have bad air or low oxygen. Avoid going in if the job can be done from outside.
  • D. Wrong: Wrong. Some gases can overcome you in seconds. Avoid entry if you can.

Explanation

Avoid entering confined spaces if the work can be done another way. If entry is essential, it needs a safe system of work and emergency arrangements.

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