CITB Electrical Safety 1 — Questions and Answers
Question 1: What voltage is recommended for portable electrical tools on UK construction sites?
- 230V AC
- 110V AC (Correct answer)
- 415V AC
- 24V DC
Correct answer: 110V AC
110V centre-tapped to earth (CTE) is the standard for portable tools on UK construction sites, limiting the maximum shock voltage to 55V.
Question 2: What colour are 110V transformer leads typically on a UK construction site?
- Blue
- Red
- Yellow (Correct answer)
- Black
Correct answer: Yellow
Yellow is the standard colour for 110V CTE cables on UK construction sites to clearly distinguish them from mains voltage equipment.
Question 3: What device should be used with 230V equipment on a construction site to provide protection against electric shock?
- Fuse box
- Residual Current Device (RCD) (Correct answer)
- Standard circuit breaker
- Step-down transformer
Correct answer: Residual Current Device (RCD)
An RCD detects earth leakage faults and disconnects the supply within milliseconds, preventing potentially fatal electric shocks.
Question 4: What is the minimum safe approach distance from overhead power lines of unknown voltage?
- 1 metre
- 3 metres
- 6 metres (Correct answer)
- 10 metres
Correct answer: 6 metres
When voltage is unknown, lines must be treated as high voltage and a minimum safe distance of 6 metres must be maintained.
Question 5: What is the first thing you should do if you find a damaged electrical cable on site?
- Repair it with insulating tape
- Continue working and report it at the end of the shift
- Stop using it and report it to your supervisor immediately (Correct answer)
- Cover it with a warning cone and carry on working
Correct answer: Stop using it and report it to your supervisor immediately
Damaged electrical cables must be taken out of use immediately and reported to prevent the risk of electric shock or fire.
Question 6: What should you do before using a portable electrical tool?
- Run it at full power to check it works
- Visually inspect the cable, plug, and casing for damage (Correct answer)
- Ensure it is connected to a 230V supply
- Remove the RCD to prevent nuisance tripping
Correct answer: Visually inspect the cable, plug, and casing for damage
A pre-use visual inspection identifies damage or defects before they can cause electric shock or injury to the user.
Question 7: Which regulation specifically covers the safe use of electrical systems and equipment in UK workplaces?
- COSHH Regulations 2002
- Provision and Use of Work Equipment Regulations 1998
- Electricity at Work Regulations 1989 (Correct answer)
- Manual Handling Operations Regulations 1992
Correct answer: Electricity at Work Regulations 1989
The Electricity at Work Regulations 1989 require that electrical systems and equipment are maintained and used in ways that prevent danger.
CITB Electrical Safety 1
What voltage is recommended for portable electrical tools on UK construction sites?