An employee received a fatal electric shock whilst changing a welding rod during arc-welding work inside a metal silo. It was found that there was a voltage of no more than 86 Volts ac between the welding rod and the silo metalwork when no welding was taking place. There was an unsafe system of work in this hazardous environment. It was found during the investigation that the electrical equipment in use at the time of the accident was damaged but this was found not to be contributory to the accident.
The employer was prosecuted under the Health and Safety At Work etc. Act 1974, Section 2, Sub Section 1, and The Management of Health and Safety at Work Regulations 1992 (No 3) paragraph 1 and entered a guilty plea at magistrates court. They were later fined £250,000 at Crown Court.
This incident shows that even relatively low voltages can deliver a fatal electric shock, particularly where a person cannot easily escape the shock, and that arc welding equipment should be switched off when rods are being changed.
Electrical work in hazardous environments should not be carried out until a risk assessment has been done and control measures identified and implemented. HSE has published guidance covering many of the common hazardous environments such as confined spaces, where there is a hazard from earthed surfaces, wet places, explosive atmospheres, deep trenches, near sewage etc. Work should not commence where there is doubt regarding the effectiveness of any control measure.