NEBOSH CC Electrical Hazards on Site 2

Question 1

What is the purpose of PAT testing (Portable Appliance Testing) on a construction site?

Accepted Answer

To check that portable electrical equipment is safe and in good working order

Answer

PAT testing involves inspection and electrical testing of portable electrical appliances to ensure they are safe. On construction sites, harsh conditions mean equipment deteriorates quickly and regular testing is essential.

Question 2

What is the safe distance that should be maintained from overhead power lines when using plant such as cranes or excavators?

Accepted Answer

At least 3 metres from uninsulated overhead lines under 33kV

Answer

The safe working distance from uninsulated overhead lines depends on voltage, but for lines up to 33kV, a minimum exclusion zone of 3 metres is typically required. Higher voltage lines require greater distances and specialist assessment.

Question 3

What measures should be used when construction plant must work near overhead power lines?

Accepted Answer

Goal posts, banksmen and exclusion zones

Answer

When plant must work near overhead power lines, goal posts (height restriction barriers) must be erected to prevent plant from reaching the lines. A banksman should guide operations, and exclusion zones must be established. The power company should be contacted to consider de-energising the line.

Question 4

What is the meaning of 'isolation' in electrical safety?

Accepted Answer

Disconnecting electrical equipment from all sources of supply and securing so it cannot be inadvertently re-energised

Answer

Isolation means completely disconnecting equipment from all electrical energy sources and securing the isolation (e.g., with a lock) to prevent inadvertent re-energisation. Simply switching off is not sufficient — the supply must be physically disconnected.

Question 5

What is the risk of using a damaged extension lead on a construction site?

Accepted Answer

Electrocution, electric shock or fire due to exposed conductors or poor connections

Answer

A damaged extension lead with exposed conductors, damaged insulation or faulty connections can cause electric shock to anyone who touches it, and may cause arcing which leads to fire. All electrical leads must be regularly inspected.

NEBOSH Construction Certificate Practice Test

NEBOSH Construction Certificate Practice Test

NEBOSH CC Electrical Hazards on Site 2