Arc Flash AwarenessHi Gibbo, I can understand your frustration with the apparent lack of direction and clarity in this area. In the UK we have a good record in electrical safety but our records of electrical accidents are poor which leads some people to think that there is not a problem. The anecdotal evidence suggests, (you personally have experience of two arc flash accidents) that we must not be complacent in this area and do much more to identify the hazard and protect workers. There are around 650 admissions to hospital beds per year for electrical accidents in England alone and whilst some of the victims are general members of the public, the fact that the majority of them are males of working age should allow you to draw your own conclusions. Rates of injuries have been rising in recent years so we must not be complacent.
A fundamental safety principle, which is embodied in UK legislation, is to design out, eliminate or remove the hazard at its source whether this is electric shock or arc flash. The Electricity at Work Regulations 13 and 14 lead to the conclusion that the majority of tasks must be carried out with the equipment made dead. Live working should never be accepted as the norm and Regulation 14 of the Electricity at Work Regulations 1989 makes clear that three conditions must be met for live working to be permitted. These conditions are:
1.It is unreasonable in all the circumstances for the conductor to be dead; and
2.It is reasonable in all the circumstances for that person to be at work on or near that conductor while it is live; and
3.Suitable precautions (including where necessary, the provision of personal protective equipment) have been taken to prevent injury.
If live working can be justified through the rigorous tests of reasonableness in conditions one and two, judgments must be made about suitable precautions against electric shock and the effects of electrical flashover to satisfy the requirements of condition three.
At this point in time it is unlikely that a UK HSE Electrical Inspector will ask to see an IEEE1584 Arc Flash Study after an electrical burn accident whilst doing live work, but instead ask for an account of what the worker was doing there in the first place. If it can be shown that it was unreasonable in all the circumstances for the conductor to be dead and it was reasonable in all the circumstances for that person to be at work on or near that conductor while it is live then the third part of regulation 14 from the EAWR 1989 will come into question. In other words, were suitable precautions (including where necessary, the provision of personal protective equipment) taken to prevent injury. The precautions should include competent staff, insulating barriers or screens, suitable test equipment & leads and accompaniment. Other precautions should include; adequate information to the person carrying out the work about the live conductors, system & foreseeable risks, protective clothing and the creation of a safe zone in which only authorised persons can be admitted.
The latter three precautions can be specified with the aid of the US standards such as IEEE 1584 that are the result of intensive empirical research. There is no other refined tool to calculate arc flash incident energy to the same detail and therefore there is, in my view, a duty to use the *latest technological advances in the evaluation of risk. (*One of the general principles of prevention from European Law which is embodied in UK legislation) The key is to use the tools available but as part of a rigorous risk assessment.
I hope that this helps but there is a seminar which has been designed to answer the questions that you raise in Watford on the 11th February 2008. Jim Phillips PE and I will be presenting and also Neil Gove who is a HM Specialist Electrical Inspector from the HSE. The links to the event are below.
http://www.elecsafety.co.uk
http://www.electricalreview.co.uk/news/118116/Exploding_the_Myths_and_Mystery_behind_Electrical_Arc_Flash.html