The worker was removing a piece of industrial equipment at a site in Wallsend in North Tyneside, Tyne and Wear. He had been contracted by Green North East Trading Bidco (GNETB), which traded as Impetus Waste Management.
On 20 March 2016 he cut through an electric cable to a fan, which he believed had been isolated because the company had told him it was safe for him to carry out the job, South Tyneside Magistrates' Court was told.
He suffered an electric shock and needed hospital treatment. He has since made a full recovery.
The Health and Safety Executive (HSE) said GNETB had not adequately planned and managed the work. It found there were several pieces of equipment that had not been electrically isolated at the site.
GNETB, which entered administration in November 2016, was found guilty of breaching s 3(1) of the Health and Safety at Work Act and ordered to pay costs of £5,390.
"This incident could so easily have been avoided if the work had been properly planned, the risks identified and steps taken to ensure that all equipment was electrically safe before the contractors started work at the site," said HSE inspector Shuna Rank.