CSCS Electrical Safety 2

Question 1

What colour is the reduced low-voltage 110V plug and socket used on UK construction sites?

Accepted Answer

Yellow

Answer

110V plugs and sockets are coloured yellow in the UK, in accordance with BS EN 60309. Blue denotes 230V single phase, red denotes 415V three-phase. This colour coding helps operatives quickly identify the voltage and select the correct equipment.

Question 2

What does a CAT scanner detect when used before excavation work near electrical cables?

Accepted Answer

Underground power cables, metal pipes, and other buried services

Answer

A Cable Avoidance Tool (CAT) detects underground power cables, telecommunications cables, and metallic pipes using different detection modes (power, radio, and Genny modes). HSE guidance PG381 requires CAT and Genny surveys before any excavation to locate buried services and prevent cable strikes.

Question 3

Under BS 7671, what is the maximum disconnection time for a 230V final circuit protected by an RCD in a TT earthing system?

Accepted Answer

0.2 seconds

Answer

BS 7671 (IET Wiring Regulations) specifies a maximum disconnection time of 0.2 seconds for socket-outlet circuits in TT systems protected by a 30mA RCD. This rapid disconnection time ensures that any earth fault is cleared before a lethal shock can occur.

Question 4

What must be done if an underground electrical cable is accidentally damaged during excavation work?

Accepted Answer

Evacuate the area immediately, report to the site manager, and contact the utility provider

Answer

If an underground cable is struck, all personnel must evacuate the immediate area as the cable may still be live. The site manager must be informed, the area secured, and the relevant Distribution Network Operator (DNO) contacted immediately. Under the Electricity at Work Regulations 1989, continuing to work near a damaged cable is extremely dangerous and unlawful.

Question 5

What is the minimum IP (Ingress Protection) rating generally recommended for electrical equipment used outdoors on UK construction sites?

Accepted Answer

IP44

Answer

IP44 is the minimum rating generally recommended for electrical equipment used outdoors on construction sites, providing protection against solid objects over 1mm and water splashing from all directions. BS 7671 and HSE guidance specify that equipment must be suitable for the environment in which it is used.

CSCS Green Card Practice Test

CSCS Green Card Practice Test

CSCS Electrical Safety 2