ELECTRICAL - 19.05.2022

Avoidable cable strike at substation

The case

VolkerInfra Ltd (V), a high voltage cabling expert contractor, had been subcontracted by principal contractor Siemens Energy Ltd (S) to carry out cabling works as part of a wider construction project at Whitegate Substation near Manchester. The excavator driver, working on behalf of V, was excavating ground for laying a 275kV cable and struck an existing live cable close by with the excavator. The contact resulted in multiple explosions which caused blistering to his retina.

The investigation

An investigation by the HSE found that the permit to dig had not been properly completed by S. It was also found that no one had checked the cable markings prior to work starting. The existing live cable had not been adequately identified by the team working on behalf of V and so the surface markings for the cable location were incorrect by around 50cm. There had also been inadequate monitoring and supervision of work.

S pleaded guilty to breaching regulation 13(1) Construction Design and Management Regulations 2015 (CDM) , was fined £900,000 and ordered to pay costs of £6,327.52. V pleaded guilty to breaching of s.3(1) Health & Safety at Work etc. Act 1974 , was fined £180,000 and ordered to pay costs of £6,430.72.

HSE Inspector Rebecca Vaudrey said after the hearing: “Those in control of work have a responsibility to devise safe methods of working and to provide the necessary information, instruction and training to their workers in the safe system of working.”

Lessons to be learnt

It’s not just on CDM projects that you need to be aware of underground services. Simply digging a hole to plant some trees on your site could land you in trouble if you have not adequately prepared for the task.

You, or your landlord, should have access to site plans to identify where there are buried services so that you can prepare for any digging works. It is a reasonably practicable control to purchase or hire a simple cable avoidance tool (CAT) as these identify buried services (see The next step ) and a trained operator will be able to assess the direction of the services and mark the ground with paint or wooden pegs. Never use steel spikes as you will not know how deep the services are buried until you have completed your trial dig and you may easily damage shallow pipework.

Tip. Don’t rely solely on plans, as things may have altered and they may not be up to date. Always make sure you are undertaking trial digs by hand rather than assume there is no danger there. Some services are buried in plastic pipes, so will not be detected using a CAT.

Tip. Buried services also include gas, water and telecommunications so always have emergency plans in place and ensure they can be adapted to each of these different services. An electricity strike will require a very different response to hitting a water main, and a gas strike may introduce the risk of fire and explosion.

For a selection of cable avoidance tools, visit https://tips-and-advice.co.uk, Download Zone, year 20, issue 17.