Steven Loake, 53, from Archway, died while trying to fix a fault on the chapel lift at Pentonville prison in Holloway on 5 October 2010.

The engineer did not isolate the lift from the power supply and was found dead by a prison employee the same day.

ThyssenKrupp Elevator UK was fined £100,000 and ordered to pay full costs of £25,748 for breaches of safety legislation identified during the HSE investigation. It was never contended that the breaches directly caused Loake’s death.

Southwark Crown Court was told that the cause of the incident was Loake coming into contact simultaneously with a live conductor and metal parts of the lift structure, thus creating a path to earth and giving him a fatal electric shock.

Investigators found the lift had not been isolated from the mains and that Loake’s multimeter, an electrical test instrument, had exposed test probes, which can lead to ‘flashovers’ or arcing.

The HSE found TKE Ltd, which was the maintenance contractor for all prison service lifts in the UK, had failed to provide a safe system of work for its field operatives, who were required to carry out work on live electrical systems.

It had not provided sufficient information and instruction concerning work on electrical systems nor supervised employees properly.

TKE also failed in its duty to ensure Mr Loake’s work equipment was fit for use. The multimeter was not maintained in good repair and insulation had been stripped back exposing an excessive amount of metal, causing an increased risk of shock and burns.

After the case, HSE Inspector John Crookes said: “The company’s failures in providing a safe system of work along with appropriate information and instruction went back more than ten years.

“The combined effect of these inadequacies was that all TKE’s lift fitters and field operatives were exposed to an unacceptable risk when working with the company’s outdated procedures.

“In that sense, Mr Loake’s death, though not directly caused by the failings, can be seen as an example of the ‘accident waiting to happen’.

“The extent of the breaches demonstrates that TKE’s performance, as one of the leading companies in the UK lift industry, fell well below the required standard. They should be setting the standard in safety and provide an example to other operators.”