Richard Baisley, 26, of Scunthorpe, received severe burns to his hands, arms, face and chest when he drilled through concrete and pierced a 415 volt cable.
The location of the cable was not established by piling specialist Kim Barker Construction before the digging work started.
Scunthorpe Magistrates’ Court heard that Baisley and a fellow employee had been instructed by a director of Kim Barker Construction to dig two holes outside their site entrance so they could erect a new company sign.
Part-way through the job, the two workers hired a drill to break through some concrete and took it in turns to use it. During Baisley’s turn, the concrete gave way and he pierced the cable, resulting in an electrical explosion.
Baisley was in hospital for three days for treatment to his burns.and he is unable to return to his original career as a welder because of the affects of heat on his skin.
Kim Barker Construction Ltd, of Flixborough Industrial Estate in Scunthorpe, pleaded guilty safety breaches and was fined £13,000 and ordered to pay £2,039.10 in costs.
Inspector John Dutton said: “This is an example of how a simple job, no matter how straightforward it may seem on the face of it, can have serious, if not fatal, consequences if not properly planned.
“There are lessons from this case that are relevant to many companies who decide to carry out work such work.
“First and foremost, when digging where underground services may be present, a firm needs to carry out an investigation to locate those services.
“It also highlights the need to make sure every job is planned, undertaken and supervised using trained workers and the right tools.”