The arc flash risks of working on live electrical equipment have been well known throughout the mining and general industry for many years, yet too many incidents still occur with tragic consequences.
For our readers who are not electrically minded, arc flashes are extreme surges of heat energy that can severely injure, or even kill, anyone within a radius of around 3 metres or more. The sound waves and pressure from a flash can even throw workers across the room in certain instances. Regular risk evaluations can play a large role in prevention, as well as proper warning signage along with infrared monitoring and employee training.
Arc Flash incidents occurring regularly
Back in February 2018, we reported on an Arc Flash Incident in a Western Australian mine which resulted in severe injuries and temporary blindness to an electrical worker and his assistant. The Western Australian DMIRS recently advised mines that, since July 2018 three electricians have suffered very serious injuries caused by arc flash incidents while they were working live on or near energised switchboards.
As recent as 20th November this year, Energy Australia confirmed that a “phase-to-phase arc flash” caused the explosion at Yallourn Power Station which lead to the death of one of its workers a day later. Graeme Edwards, a unit controller with more than 30 years’ experience, was critically injured during the arc flash explosion.
In Western Australia in May 2018, working on or near energised electrical installations (live work) became illegal under Regulation 55 of the Western Australian Electricity (Licensing) Regulations 1991. The requirements to assess risk and commence work is only permissible after specific criteria have been met and rigorous safety measures are implemented (Refer to r. 55 extract).
Australian Standards : Why not one Arc Flash Prevention Standard?
For many in the industry (both electrical and safety personnel), there appears to be some
ambiguity and/or confusion across the range of standards to be used….rightly so. While the new AS/NZS 3000:2018 Electrical Installations (Wiring Rules) provides a new section detailing the requirements for protection against Fire Hazards due to Arcing Faults plus an Appendix to provide an understanding of the types of arc faults and requirements for the Arc Flash Detection Device (AFDD), a number of other standards may also apply.
AS/NZS 3007:2013 Electrical equipment in mines and quarries—Surface installations and associated processing plant specifies the requirement to define arc flash energy levels and to advise that personal protective equipment is required when performing any work in the proximity of switchgear.
It is also apparent that for a significant time, Australian electricians and electrical engineers may have anecdotally applied the USA NFPA arbitrary standard based incident energy of 40 cal/cm2 to identify a ‘serious’ event that required a level of protection. ENA NENS 09-2014 National Guideline for the Selection, Use and Maintenance of Personal Protection Equipment for Electrical Arc Hazards corrected that, and essentially removed the use of cotton PPE and mandated arc rated PPE recognising that an incident below the 40 cal/cm2 threshold could be serious. Recent updates have identified that the arbitrary use of this incident energy may not a good measure of the pressure wave that potentially may be created by an arc event.
The fundamental absence of one technical standard in Australia regarding Arc Flash has resulted in the adoption of a plethora of other relevant standards including international alternatives. The US Based NFPA 70E 2018 update and IEEE 1584 (Calculation of Incident Energy and boundaries) are two that are heavily relied on by design engineers.
We do appreciate that there is a range of work being undertaken by various regulators across Australia to assist the industry manage the risk and and come to terms with the many standards.
Ultimately, we must recognise that there is no ‘Safe Arcing Fault’ across the mining industry and despite a range of PPE being available to effectively provide levels of protection against Arc Flash Events, we should be seeking to eliminate live work.
Western Australia takes a stand on Arc Flash
The DMIRS has taken a tough stand on Arc Flash advising mines that ‘live electrical work’ is not acceptable and may only be conducted after exhausting all other avenues to isolate the work and provide adequate protection. The WA regulator said in their latest bulletin “In the light of this spate of arc flash incidents, Building and Energy is sending this message to every licensee to reinforce yet again that R. 55 must be complied with in every instance. Appropriate enforcement action will be taken for every case of R. 55 breaches.”
They added “If convicted of such a breach, those responsible may incur penalties of $250,000 for an electrical contractor or $50,000 for an employed electrician.”
In Western Australia, if a live work incident occurs on a mine site, the electrical contractor, employed electrician and person in charge could be liable for prosecution under the Mines Safety and Inspection Act 1994, with penalties ranging up to:
- $2.7 million for companies;
- $550,000 and imprisonment for five years for individuals (self-employed); and
- $100,000 for employees.
Additionally, those in charge of other workplaces where such incidents occur may be subject to similar penalties under the Western Australian Occupational Health and Safety Act 1984.
The productivity issues surround Arc Flash incidents also should not be underestimated. The loss of key switchboards can costs mining sites and other organisations, considerable productivity/production costs while plant remains inoperable following an incident.
The potential loss of life or serious injury to workers from Arc Flash incidents is one that requires immediate attention. The obligations of sites for live electrical work, while well known, must be adequately managed. Arc Flash continues to be a serious threat to those working with energised equipment across the industry.
NOTE: This article is for general reference purposes only. We would strongly recommend that readers consult their local regulations and procedures for assessing arc flash risks and preventing arc flash fatalities and injuries.
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