CITB Electrical Safety 1

Question 1

What voltage is recommended for portable electrical tools on UK construction sites?

Accepted Answer

110V AC

Answer

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?

Accepted Answer

Yellow

Answer

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?

Accepted Answer

Residual Current Device (RCD)

Answer

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?

Accepted Answer

6 metres

Answer

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?

Accepted Answer

Stop using it and report it to your supervisor immediately

Answer

Damaged electrical cables must be taken out of use immediately and reported to prevent the risk of electric shock or fire.

CITB HS&E Operatives Practice Test