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Frequently Asked Questions

What is Arc Flash?

An arc flash is a type of explosion that results from a short circuit that flashes over from one exposed to live conductor to another conductor or to ground.  It is a serious hazard that is caused by electrical arcs that can vaporize metals, plastics, and flesh.  Arc flash incidents are extremely dangerous and are potentially fatal to workers.  

Light – the light emissions can be like looking into the sun on a bright sunny day, casing permanent damage to the retina.

Heat – temperature of the arc can reach 35,000 degrees Fahrenheit (up to 4X hotter than the sun). Because an arc flash can extend beyond a workers position, 360° of protection is needed. With the melting and vaporizing of metals and other materials, the presence of toxic fumes will instantly be present.

Arc Blast – superheated air and vaporized solids surrounding the arc, expand out from the fault at supersonic speeds. The arc blast also sends a sound wave loud enough to cause irreparable damage to a workers hearing.

Where does it happen?

Arc flash can occur at any location where electricity is present and this includes residential, industrial, and commercial facilities. It can happen with or without the presence of a worker.  Statistics say that a worker is injured every 30 minutes from electrically induced causes. 

Who is at risk for Arc Flash?

Electricians, maintenance workers, operators, and workers who are exposed to energized equipment are at risk for an electrical arc flash.  Therefore, operations that inspect, repair or maintain electrical equipment are subject to NFPA 70E guidelines.  These operations include Chemical Plants, Food Processing, Auto Manufacturing, Metal Working, Petroleum Refining, Hospitals, Paper and Pulp, Retailing, Printing, and other manufacturing companies.

What Causes Arc Flash?

An arc flash happens when current flows through an air gap between conductors.  Most accidents are caused by touching a test probe to the wrong surface or dropping a tool that can create a spark that will ignite.  Other causes of Arc flash are:
•    Dust, corrosion or other impurities on the surface of the conductor
•    Equipment failure due to improper installation, or normal wear and tear, or use of substandard parts
•    Coming close to a high-amp source with a conductive object

What kind of injuries and what are the costs of Arc Flash injuries?     

•    Skin burns by direct heat exposure.  Large amounts of heat can  set clothing on fire and severely burn human skin
•    High-intensity flash can cause damage to eyesight
•    Other physical injuries may also result from being blown off ladders or shrapnel wounds from metal parts
•    Death is also a possibility with arc flash or arc blasts

Most electrical accidents are due to arc flash and not from shocks.  More than 2,000 people are admitted annually to hospitals or burn centers with severe arc flash burns. Costs to the worker or to your company may be significant and devastating.  Medical treatment may sum up to millions of dollars or your company may be tied up to expensive lawsuits with victims and their families.  Or it may even result to a plant shut down for a period of time if equipment is damaged and needs to be repaired or replaced.

How do we prevent or reduce the risk of Arc Flash?

•    To know how much danger is present, Arc Flash Hazard Analysis needs to be conducted and should only be undertaken by professionals with necessary qualifications to perform
•    Arc flash training would give worker better understanding of the hazards of arc flash
•    NFPA 70E specifies areas where arc flash protection is required for workers involved in the maintenance of energized or potentially energized electrical equipment.  NFPA 70E standard and OSHA regulations MUST be met. With proper use of PPE (Personal Protective Equipment), risks in potential Arc Flash environments can be mitigated.

What is an Arc Flash Hazard Analysis?

An arc flash analysis per the NFPA 70E is a study investigating a worker’s potential exposure to arc flash energy, conducted for the purpose of injury prevention and the determination of safe work practices, arc flash boundary and the appropriate levels of personal protective equipment (PPE). It is critical to worker and workplace safety to analyze arc flash hazards.  NFPA has identified FR hazard risk category levels which are numbered by severity from 1-4.  Hazard risk Category is the level of arc flash protection clothing a worker must wear to protect against a minimum level of incident energy measured in calories per centimeter squared. Meaning, electrical equipment, depending upon the energy delivering capability, under fault conditions can cause an explosion, or arc fault of a certain level, again measured in calories per centimeter squared. 

  • Arc Rating Explained - A value of the energy necessary to pass through any given fabric to cause with 50% probability a second or third degree burn. This value is measured in calories/cm². The necessary Arc Rating for an article of clothing is determined by a Hazard/Risk Assessment and the resulting HRC. Usually measured in terms of ATPV ( Arc Thermal Performance Value) or EBT (Energy of Breakopen Threshold) . The higher the ARC rating value the greater the protection. When the product is sold to protect workers from arcing faults, clothing manufacturer are required in indicate the ARC rating.


What is Arc Flash PPE?

The arc flash hazard analysis allows for calculation of Arc Flash Incident Energy levels (AFIE). The categories (0 - Dangerous) determine the amount of protective clothing and personal protective equipment (PPE).  Table 130.7(C)(16) in the NFPA 70E carefully outlines the requirements for each category.

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