Electrical Safety on Irish Construction Sites: Temporary Installations and Overhead Lines

Electrical hazards on Irish construction sites cause fatalities and serious injuries every year.

The Scale of the Electrical Hazard

Electrical accidents on Irish construction sites cause fatalities and serious injuries every year. Contact with overhead power lines by plant and machinery is one of the most common causes of electrical fatalities in the construction industry. Faults in temporary electrical installations cause electrocution, burns, and fires. Striking buried electrical cables during excavation work is a persistent hazard on Irish sites.

Electrical hazards are particularly dangerous because they are often invisible. A live conductor looks the same as a dead one. An overhead power line that appears to be high enough to clear a passing vehicle may be lower than it looks, particularly where the line sags in warm weather. A buried cable that is not shown on the service drawings may be exactly where the excavator is digging.

The Legal Framework

Electrical safety on Irish construction sites is governed by the Safety, Health and Welfare at Work (General Application) Regulations 2007, Part 3 Chapter 1 (Electricity), and the Safety, Health and Welfare at Work (Construction) Regulations 2013. The General Application Regulations require employers to ensure that electrical equipment is suitable for its intended use, is maintained in a safe condition, and is used only by competent persons. The Construction Regulations require the PSCS to ensure that electrical installations on the construction site are safe.

The Electricity Regulation Act 1999 and the Electricity Supply Board's (ESB) network regulations also impose obligations on those working near ESB infrastructure, including overhead power lines and underground cables.

Temporary Electrical Installations

Temporary electrical installations on construction sites must be designed, installed, and maintained by a competent electrician. The installation must comply with the relevant Irish Standard, IS 10101 (National Rules for Electrical Installations), and must be inspected and tested before being put into service and at regular intervals thereafter.

The key requirements for temporary electrical installations on construction sites include the use of reduced low voltage (110V) systems for portable tools and equipment wherever practicable. The 110V centre-tapped earth (CTE) system reduces the maximum shock voltage to 55V, significantly reducing the risk of fatal electrocution compared with 230V systems. Where 230V equipment must be used, residual current devices (RCDs) with a tripping current of 30mA must be installed to provide additional protection against electric shock.

All electrical equipment used on construction sites must be inspected before use and must be maintained in a safe condition. Damaged cables, broken plugs, and defective tools must be taken out of service immediately and must not be used until they have been repaired or replaced by a competent person. Records of inspections and maintenance must be kept.

Overhead Power Lines

Contact with overhead power lines is one of the most common causes of electrical fatalities in the Irish construction industry. Plant and machinery, including excavators, telehandlers, cranes, and tipper trucks with raised bodies, can easily reach the height of overhead power lines, particularly distribution lines which may be as low as five metres above ground level.

Before any work begins on a site near overhead power lines, the PSCS must assess the risk and implement appropriate controls. The preferred control is to have the lines diverted or de-energised by the ESB before work begins. Where this is not practicable, the lines should be protected by goal posts and barriers that prevent plant and vehicles from approaching within the safe working distance.

The safe working distances from overhead power lines depend on the voltage of the line. For low voltage lines (up to 1,000V), the safe working distance is three metres. For high voltage lines (above 1,000V), the safe working distance is greater and must be confirmed with the ESB before work begins. These distances must be maintained at all times, including when plant is travelling, when loads are being lifted, and when vehicles have raised bodies or extended booms.

All workers on sites near overhead power lines must be briefed on the hazard and the controls in place. Banksmen must be provided where plant is operating near overhead lines, and the banksmen must be trained in the specific hazards of working near live power lines.

Buried Electrical Cables

Striking a buried electrical cable during excavation work can cause electrocution, burns, and fire. The risk is particularly high on urban sites where the ground is densely serviced. Before any excavation work begins, the PSCS must ensure that service drawings have been obtained from the relevant utility companies and that the position of buried cables has been identified using cable locating equipment.

Hand digging must be used in the vicinity of identified buried cables. Mechanical excavation must not be used within 500mm of an identified cable. Where the position of a cable cannot be confirmed, hand digging must be used until the cable has been located and its position confirmed.

Conclusion

Electrical hazards on Irish construction sites are serious and often fatal. The controls required are well established: competent design and maintenance of temporary installations, the use of 110V systems and RCDs, safe working distances from overhead power lines, and careful management of buried cables. Employers who apply these controls consistently protect their workers from one of the most dangerous hazards on any construction site.