A little bit more about Arc Flash
WHAT IS ARC FLASH?
An Arc Flash is an explosive release of energy caused by an electrical short circuit between 2 energised conductors or an energised conductor and earth. The sudden discharge of electrical energy causes a brilliant explosion of light and sound. The temperatures inside an Arc Flash incident can reach 19,000°C (sun’s surface temperature is 6000°C) causing conductors especially copper to vapourise. The explosion causes shrapnel and vaporized conductors to escape the blast site at 1600km/hr. This amount of energy is sufficient to cause severe injury to anyone within the blast radius. The injuries can range from burns, blindness, hearing loss, impact injury, psychological trauma and even death. Critically, most Arc Flash incidents happen when the electrical system is being worked on and “live” and thus Arc Flash presents a serious risk to the employees.
The incident energy in an arc flash incident does not necessarily depend on the system voltage because the lower the voltage, the more current there can be in the system and the higher current levels create the high amounts of energy that is dissipated in an arc flash incident in an electrical system.
ARC FLASH AND THE LAW
Health and safety legislation in Ireland and the UK imposes numerous duties on employers and the self-employed (contractors) in relation to Arc Flash and electrical safety in general. Employers must ensure, so far as reasonably practicable, the safety, health and welfare at work of employees and any other persons who may be affected by their undertakings (Safety, Health & Welfare at Work Act 2005 in ROI, The Health and Safety at Work Etc. Act 1974/N.I Order 1978 in UK). Notably, this general duty extends to the provision and maintenance of safe plant and systems of work, and also the provision of such information, instruction, training and supervision as is necessary. Arc Flash and other hazards associated with electricity at work must be managed in this context.
More specifically, employers must make a suitable and adequate assessment of the risks to health and safety, and those include Arc Flash and other risks involving electricity, and to put in place the necessary preventive and protective measures (2005 Act in ROI, Safety at Work Regulations 1999/N.I. 2000 in UK).
Persons engaged in any work activity involving electricity, must be competent to prevent danger (Safety, Health & Welfare at Work General Application Regs. 2007 Part 3 in ROI, Electricity at Work Regs. 1989/N.I.1991 in UK). That means, not only to have appropriate technical knowledge, but also understanding of the hazards, risks and work precautions to be observed.