Arc Flash Safety and Its Role in Mining

Within any type of industry that involves the use of electrical equipment, the potential occurrence of an arc flash poses a dangerous risk to these workers each day. An arc flash describes the explosive release of thermal energy following any fault within an electrical power system. As the fifth leading cause of work place fatalities that occur in the United States alone, proper preventative measures and awareness of the causes of arc flashes is crucial.

Associated Hazards

The most common causes of arc flashes within any industry is associated with the making or breaking of a circuit, as well as during an attempt to insulate an air gap with a more conductive object in an electrical system.

While arc flashes can occur spontaneously, the contact of any potentially conducting object, such as corrosion, tools that have been dropped near a circuit or a buildup of conductive dusts around the system can induce an arc flash. To put the explosive force of an arc flash into perspective, a short circuit occurrence on a 10,000A arc within a 480 volt circuit could detonate with a force that is comparable to eight sticks of dynamite1.

The thermal energy that is produced as a result of arc flashes can be devastating to any worker that is within the affected boundaries of the blast. With a central heat magnification that can measure up to 36,000 °F, which is almost four times greater than that which is present on the surface of the sun.

In addition to devastating third degree burns to any affected individual, arc flashes can also severely damage retinas from the ultraviolet (UV) light that follows a blast. To minimize the extent of these injuries, personal protective equipment (PPE) such as fire resistant clothing and protective eye gear must be used by all employees who work in high-risk occupational fields.

Arc Flash Regulations

In the United States, the Occupational Safety and Health Administration (OSHA) recognizes NFPA-70E, which is a document that describes the mandated standards that must be kept to ensure electrical safety within a given workplace2. To create an electrically safe working condition for workers, the NFPA-70E provides the following requirements:

  • All employees who face a risk of electrical hazards must be trained to recognize and respond to specific hazards
  • Appropriate use of PPE
  • All power sources be identified for any electrical equipment in use
  • Voltage testing of equipment
  • Proper labeling of all electrical equipment to include the system voltage and arc flash boundary

Arc Flash Prevention

Within any industry that is susceptible to the occurrence of arc flashes, employees must be educated on the ways in which they can protect themselves during an emergency, as well as what precautious measures must be taken to prevent these events from occurring.

In addition to wearing PPE when performing any type of work that involves electrical equipment, workers must also fully understand safety labels that describe the potential arch flash risk of a specific piece of equipment.

Arc flash boundary labels on electrical equipment describe how far an employee must remain from the equipment in order to be safe in the event that an arc flash occurs. All electrical equipment is also required to state the nominal system voltage, which is an important factor to recognize as higher voltages can encourage larger and often more destructive arc flashes.

Eaton Arc Flash Reduction Systems

The U.S. based power management company Eaton is dedicated to providing energy-efficient solutions to various industries around the world that require safe and sustainable working environments for their electrical equipment needs3. Some of their products that specifically function to prevent or reduce the magnitude of arc flashes include:

Arc Resistant Switchgears

  • Medium voltage (MV): Protects workers from arcing flashes in systems of 6-15 kilivolts (kV).
  • Low Voltage (LV): Protects and controls systems of 600 volts (V) or less.

Arch Resistant Motor Control Centers (MCC)

  • Ampgard MCC
  • FlashGard MCC

Image Credit:

Leigh Prather/ Shutterstock.com

References:

  1. “Top ten list” – Eaton
  2. “Arc Flash Awareness” – The Centers for Disease Control
  3. “Arc Resistant Switchgear” – Eaton

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