An electrical contractor has been handed a £70,000 penalty after a groundworker was electrocuted when he grabbed the uninsulated ends of a live cable.

South Eastern Electrical had been contracted to replace lighting in a supermarket carpark during the refurbishment of the premises in Southend, Essex. The firm subcontracted two electricians to carry out the work without instructions or a circuit diagram. South Eastern had made no attempt to survey the lighting columns in the carpark to identify their electrical supply point and, though the electricians' supervisor had showed them a distribution board where they could isolate the supply, it wasn't clear which columns the board fed.

The electricians had replaced the lighting in three columns and after finding the electrical supply was dead, assumed a fourth was safe. But the fourth column was supplied by a different distribution board and was activated by a light sensor. It had been daylight when they originally tested it for current, but as the light faded, the circuit was energized. An electrician touched a live cable and was knocked unconscious by the shock, and suffered burns and bruising.

HSE inspector Dominic Elliss said simple controls such as identifying and isolating the electrical supply, together with clear instructions and supervision, would have prevented the incident. The firm had no permit to work system covering who had to make which columns safe and how.

At Basildon Crown Court on 5 March, South Eastern Electrical was fined £50,000 with £20,000 HSE costs, for failing to protect the electricians' safety, contrary to Section 3(1) of the Health and safety at Work Act.