CSCS Ireland Excavations and Electrical Safety

Question 1

Before commencing excavation work on a construction site in Ireland, what must be done regarding underground services?

Accepted Answer

The location of all underground services (gas, electricity, water, telecoms) must be identified and marked before digging begins

Answer

Before any excavation, all underground services must be identified using service drawings, CAT scanning (Cable Avoidance Tool), and liaison with utility companies. Striking a live cable or gas main can be fatal.

Question 2

What is the recommended minimum safe distance from an underground electrical cable when using a mechanical excavator?

Accepted Answer

0.5 metres — hand digging should be used within 0.5 m of a known cable

Answer

Mechanical excavation should stop at least 0.5 metres from a known buried electrical cable. Hand digging should then be used to expose the cable safely. Even with marking, cables may not be exactly where records show.

Question 3

What must be provided at the edge of every excavation over 2 metres deep on a construction site?

Accepted Answer

Barriers or guardrails to prevent people and vehicles from falling in

Answer

Excavations over 2 metres deep must have rigid barriers or guardrails around the edges. Warning signs alone are insufficient as people or vehicles can still fall or drive into unprotected excavations.

Question 4

What is the primary risk of excavation collapse on a construction site?

Accepted Answer

Workers being buried alive or crushed, which can be fatal within minutes

Answer

An excavation collapse can bury a worker in seconds under tonnes of soil. Rescue is extremely difficult and often fatal. Ground conditions must be assessed and appropriate support (trench sheets, shoring, battering) installed.

Question 5

What is the safe voltage for portable electrical tools used in damp or confined conditions on Irish construction sites?

Accepted Answer

110 volts (centre-tapped to earth, with a maximum of 55 V to earth)

Answer

110 V centre-tapped to earth (CTE) is the standard safe voltage for construction sites in Ireland and the UK. The maximum voltage to earth is 55 V, significantly reducing the risk of a fatal shock compared to 240 V mains supply.

CSCS Ireland Practice Test

CSCS Ireland Practice Test

CSCS Ireland Excavations and Electrical Safety