Bury Council has appeared in court after one of its employees suffered an electric shock from a 230 volt mains cable.
The worker from Prestwich, who asked not to be named, suffered burns to his wrist, leg and groin and singed his facial hair while removing a lamp post on Harper Fold Road in Radcliffe on 9 June 2011.
The local authority was prosecuted by the Health & Safety Executive after an investigation found he had received inadequate training and supervision for the work.
Trafford Magistrates' Court heard on Friday that new street lights were installed on the road and the old lights disconnected.
The injured worker and a colleague were in the process of removing one of the old lamp posts, using a jackhammer to break the concrete around the base, when he struck a mains electricity cable.
HSE discovered the two workers had not been given service drawings for the lamp post they were removing, which would have shown where the mains cable ran.
Their manager had not received any health and safety management training, despite it being part of his job to ensure work was carried out safely.
Bury Council, of Knowsley Street in Bury, was fined £20,000 and ordered to pay £7,594 in costs after pleading guilty to breaching the Health & Safety at Work etc Act 1974 by failing to ensure the safety of workers.
John McGrellis, HSE principal inspector, said: "The council employee needed several days off work to recover from his burn injuries but he could easily have been killed.
"He shouldn't have been put in a situation where he didn't know what the potential dangers were as he used a jackhammer to break up the concrete around the lamp post.
"It's vital that people carrying out work near to power lines receive appropriate supervision and training to ensure their safety."
A Bury Council spokesman said: "On this occasion, we failed to live up to the high health and safety standards and procedures expected of us and desired by us. We acted speedily after the incident and have co-operated fully with the HSE at every step, and accept the judgement of the court.
"Since this incident, we have invested a considerable amount of time and money into making improvements. These include: buying new state-of-the-art detection equipment, providing a comprehensive training framework for staff, introducing new digital software to support better recording procedures, created a new risk assessment framework/procedure, strengthened corporate health and safety across the council, and appointed a Lead Director on behalf of the Strategic Leadership Team.
"We hope that these actions show how determined we are to learn from what went wrong and make Bury a place where all employees take health and safety seriously, have the right experience, the right level of training and support, and to embed good and safe working practices into their daily work."