A principal contractor and its subcontractor have both been fined over the incident on 12 April 2017.
Chelmsford Magistrates’ Court was told that two demolition workers employed by subcontractor R B Haigh and Sons were removing electrical distribution equipment from a switchgear room at the former Molecular Products site in Thaxted, Essex.
One of the employees, Alan Banks, had been told by A J Wadhams and Co, the PC for the demolition work, that the electrical equipment had been isolated.
To reassure his colleague that it was safe, he threw a crowbar at the 400V ac equipment.
However, the power supply had not been isolated and the crowbar came into contact with live exposed wires. This caused a flashover with temperatures of more than several thousand degrees and a subsequent fire.
Banks sustained serious burn injuries and was hospitalised immediately.
Investigating, the Health and Safety Executive (HSE) found that the work had not been properly planned and suitable control measures were not in place to ensure the power supply had been isolated.
It said that A J Wadhams and Co had failed to follow “clear procedures” outlined in its risk assessments and method statements, which required all equipment to be treated as live unless written authorisation proved otherwise.
The company, trading as Wadham Homes, pleaded guilty to breaching s 3(1) of the Health and Safety at Work Act and was fined £80,000 plus £3,816.
Russell and Stuart Haigh, partners of R B Haigh and Sons, pleaded guilty to breaching reg 3(1) of the Electricity at Work Regulations and were also fined £80,000.
HSE inspector Adam Hills said: “This incident has had a significant impact on Mr Banks’ life and the injuries could so very easily have been fatal. Had the companies followed the control measures outlined in their respective risk assessments, then this incident would not have occurred.
“Never assume that an electrical supply is disconnected. Always check with the Distribution Network Operator or a qualified electrician to obtain written proof of isolation before commencing work.”