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HS&E RAAC practice question: Electrical isolation (1 of 5)

E. Specialist: HVACR – refrigeration and air conditioning A free question from our original HS&E RAAC practice exam. Try it, then open the answer to see why each option is right or wrong.

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

You are about to replace a compressor contactor on an air conditioning unit.

What must be done first?

Choose one answer.

  1. A. Work on it live, carefully
  2. B. Check it with your finger
  3. C. Make it dead and prove it dead
  4. D. Switch off at the unit and hope for the best
Show the answer and explanation

Answer: C

  • A. Wrong: Wrong. Don't work live if it can be avoided.
  • B. Wrong: Wrong. That could kill.
  • C. Right: Right. HSE says electricity supplies should be made dead and proved to be dead before work starts.
  • D. Wrong: Wrong. It must be proved dead.

Explanation

Make the supply dead, prove it dead, and stop it being switched back on.

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