The 22-year-old from Prescott had been told the electricity supply had been disconnected but was thrown across a basement when his angle grinder made contact with the live wires.

Construction firm Vermont Capitol Ltd was prosecuted by the HSE following the incident at a building site on Shaw Street on 2 August 2013.

Liverpool Magistrates’ Court heard that the company was clearing the site before building a block of around 60 student flats at the end of a row of Grade-II-listed Regency terraced houses, dating from the 1830s.

The end terrace had been partially demolished after becoming structurally unsound, leaving just the façade and basement on the building site.

The court was told the worker had been asked to remove old pipes and cables from the cellar but Vermont Capitol had failed to ensure the mains supply into the building had been disconnected, despite informing the site manager that it had.

There was a flash as the labourer cut into the cable and he suffered injuries to his elbow and shoulder after being thrown across the room. His protective clothing prevented him from suffering burns or being more badly injured.

Vermont Capitol Ltd, of Argyle Street in Liverpool, was fined £2,000 and ordered to pay £980 in prosecution costs after pleading guilty to a breach of the CDM regulations.

Speaking after the hearing, HSE Inspector Chris Hatton said: “This young worker is extremely lucky to be alive after suffering an electric shock from a mains cable likely to be carrying at least 240 volts of power.

“The team on the site had been told all of the utilities entering the site had been disconnected and so the worker had no way of knowing he was actually cutting into a live electricity cable.

“It’s vital that developers take the risks seriously from gas pipes and electricity cables and get written confirmation that supplies have been disconnected before starting work. Otherwise lives will continue to be put at risk.”