The lorry, belonging to Hazelton Homes (Midlands) Ltd, was delivering stone at Old Hall Close, Cottesmore, on 28 March 2012 when the raised tipper body struck the power lines above, bringing them to the ground.
The strike caused a power cut to 11 nearby homes, which were without electricity for three hours.
The Health & Safety Executive (HSE) decided to prosecute and the case was heard by Leicester magistrates yesterday.
The court heard that two weeks before the incident, the company's quantity surveyor had warned about the dangers of overhead power lines and the need for barriers and warning signs. However, none were provided. Nor had power lines been made dead or redirected away from the access road.
Hazelton Homes (Midlands) Ltd pleaded guilty to breaching regulation 34(2) (c) of the Construction (Design and Management) Regulations 2007 and was fined £8,000 with costs of £4,214.
Speaking after the hearing, HSE inspector Linda-Jane Rigby said: "This incident was entirely preventable and arose from a clear failure to assess and manage the risks associated with the presence of overhead power lines.
"The need for goalposts and warning signs had been drawn to the attention of Hazleton Homes (Midlands) Ltd shortly before this incident but the directors failed to put the necessary measures in place. Once remedial steps were taken, the company failed to ensure they remained in place.
"A number of people die every year when they accidentally make contact with electrical cables. It was only a matter of luck that no-one was seriously injured or killed in this incident."