An electrical contractor has been fined £100,000 after an employee died when he was electrocuted while fitting wiring in a building society refurbishment.
Barry Martin, 28, of Redhill, Surrey, suffered a shock to the head when a colleague mistakenly turned on the power in June 2003.
His employer, Cheltenham-based CFR Group plc, admitted breaches of health and safety legislation.
At the Old Bailey, the firm was also ordered to pay £33,000 costs.
Mr Martin, had been working for more than 66 hours a week over 11 weeks on the refitting at the Halifax branch in central London, the hearing was told.
Judge Richard Hone said it was an "unnecessary and tragic death", adding that it was a "matter of regret" it had taken four years to come to court.
The firm, which employs 130 people, had an unblemished safety record since 1946 and an £11m annual turnover, the court heard.
In the case of Mr Martin, however, it failed to ensure power switches were padlocked closed so that they could not be switched on by accident.
The company was also fined £750 for breaking working time regulations.