If you’ve ever seen an arc flash in person, you know how sudden and terrifying they can be. Often fatal, arc flashes occur “whenever there is a loss of insulation between two conductive objects at sufficient potential (voltage)” (ABB Inc., 2009). In other words, they occur when there is an arc fault; the air becomes a conductor and an extremely dangerous electrical explosion ensues. If you're working near an energized area, you're at risk for arc flash exposure.
According to Electrical Safety Foundation International, the primary causes of electrical deaths are contact with an overhead powerline, wires/transformers or with electrical current from a machine or tool (ESFI, 2010).
Even if an arc flash is not fatal, the results can still be devastating. The medical bill for one injury can exceed $1 million and permanent injuries greatly reduce the quality of life for the worker (WPSAC). According to the Workplace Safety Awareness Council (WPSAC), arc flash exposure can result in the following hazards:
- Building fire
- Blast pressure
- Heat that exceeds 35,000°F
- Deafening sound blast
Arc flashes are measured using Arc Flash Incident Energy (AFIE) and by its Flash Protection Boundary (FCB). These measurements determine the type of Personal Protective Equipment (PPE) to wear around a live part and other safety precautions.
According to WPSAC the three boundaries, starting with the outermost distance, are:
- Flash Protection Boundary – This outer boundary is where a worker exposed to an arc flash would receive second-degree burns. These burns are curable and usually not fatal. Within this boundary, flash protective equipment is required.
- Limited Approach Boundary – A shock hazard exists for the worker within this boundary. Only qualified workers that have received proper training are allowed to cross this line. Workers must continue to wear flash protective equipment.
- Restricted Approach Boundary – This is restricted space and is considered the equivalent to working on a live part. Only qualified workers who are wearing PPE appropriate for working on live parts, have received specialized training pertaining to working on live parts, and have a documented risk hazard plan are allowed within this boundary (WPSAC).
To calculate a specific boundary distance, there are a few different methods that involve complex calculations. Each method has its limitations and should only be performed by a trained professional. For more information on these methods, download National Fire Protection Association Document 70E and reference Annex D (NFPA 70E).
Training and Procedures
Training for those working around energized units is essential and must be performed every 3 years (Salisbury, 2015). Training includes instruction on how to work safely within a boundary, contact release, and basic resuscitation. Contact release training teaches one how to safely remove a victim who is within contact of a part. Resuscitation training ensures the ability of a worker to provide life-saving care in the form of CPR and AED use.
Personal Protective Equipment
PPE should always be worn when working within an arc flash boundary. The proper PPE must include all clothing worn by the worker that is flammable, yet allow the worker to move and see freely. These items also should be worn:
- Nonconductive head protection that covers the face, neck, and chin.
- Proper eye and hearing protection
- Dielectric footwear
- Rubber insulating gloves and sleeves with leather protectors (NFPA, 2015)
Tests should also be done on the equipment in accordance with Table 130.7(C)(7)(c) shown at right.
As with many policies, receiving buy-in from the workers affected is crucial to the success of the initiative. To that end, there are three things to think about as you respond to potential hazards in your workplace.
1. Workers must be held accountable for their safety and the safety of others. When implementing any new procedure, a firm and fair commitment to accountability shows that the company is serious about the new initiative and helps reinforce new habits among long-time staff members.
2. There should be clear communication on who is properly trained to enter arc flash protection areas, who is responsible for making sure the proper PPE is worn, and what each individual's role is throughout the different procedures, as well as individual responsibilities during an emergency.
Update: ISO has adopted this symbol, meaning "to warn of arc flash."
3. Executive and supervisory actions should be consistent with the new rules put in place. Regardless of the worker's role, they need to follow the procedures faithfully. When workers see executive leadership taking new policies seriously, it leads to much higher levels of cooperation.
Organizational safety starts with knowledge of potential dangers and a willingness to improve. ORR Safety is committed to helping you ensure a safe environment and provide the PPE workers need to be protected. If you need PPE to keep your workers safe from arc flash exposure or if you’d just like an ORR Safety expert to be a second set of eyes during a hazard assessment, please give us a call or send us an email. We’d be honored to partner with you to make sure your people go home safely at the end of their shift.
ABB Inc. (2009) Arc Flash Hazards. Retrieved from https://library.e.abb.com/public/2b5f3d9051ccdd76852576ac006dc16b/1SXU210204G0201.pdf
ESFI: Electrical Safety Foundation Internation (2010) Electrical Safety Then & Now. Retrieved from http://files.esfi.org/file/Electrical-Safety-Then-and-Now.pdf
NFPA (2015) 70E. Retrieved from http://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards?mode=code&code=70e
Salisbury 2015 NFPA 70E Updates Powerpoint
WPSAC: Workplace Safety Awareness Council. Understanding "Arc Flash". Retrieved from https://www.osha.gov/dte/grant_materials/fy07/sh-16615-07/arc_flash_handout.pdf