Safety First! Preventing Arc Flash Hazards

Every year, electrical safety accidents rank in the top ten of workplace-related fatalities and cause 75,000 plus workers to miss time to due shock and burn injuries.

The threat of inadvertent shock, electrocution, and fire from electrical equipment has long been a known hazard in the electrical industry. In the last 20 years, however, the industry has turned its eyes towards arc flash events as a main point of emphasis. In addition to worker and employee awareness, national code and standard bodies have made great strides in trying to understand the science of these hazards, how they happen, and how to prevent them. Compliance requirements get more comprehensive with every standard release.

NFPA 70 (National Electrical Code) governs safe and reliable electrical installations, limiting shock and fire hazards and making sure anyone coming in contact with the electrical system is aware of those hazards. NFPA 70B (Recommended Practice for Electrical Equipment Maintenance) outlines system maintenance and inspection requirements. NFPA 70E (Standard for Electrical Safety in the Workplace) defines worker and employer safety requirements and best practices.

While NFPA 70 is an adopted, enforceable code, NFPA 70E is an industry standard. Even though NFPA 70E is not directly enforceable by local authorities it is referenced within the federal Occupational Health and Safety (OSHA) guideline, which utilizes the compliance requirements outlined in NFPA 70E to fulfill its own general electrical safety requirements. As all employers know, OSHA has the authority to impose heavy fines and penalties to those found to be in violation of its requirements. So even though NFPA 70E is not code, failure to comply with its requirements can have substantial consequences.

An arc flash event is a phenomenon where electrical current leaves its intended path and travels through the air, causing a sudden, massive release of electrical energy. This release of energy coincides with an instantaneous release of superheated gases which can cause severe damage to nearby equipment and personnel. These events can be triggered by something as simple as a worker dropping a tool onto exposed live equipment or dust, condensation, or poor system maintenance. In addition to direct damage from the heat (up to 35,000 degrees) or resulting fire, an arc flash event can also cause damage from flying objects (often molten metal), pressure (from the expansion of gases), and sound (can reach over 140 dB). The size of the event is a function of several things such as available fault current, size and construction of the associated electrical equipment, magnetic forces, and closure time.

That said, as an employer/owner, what are your responsibilities?

  • Create an electrical safety plan and ensure all workers are familiar with plan (live work, LOTO, PPE, etc.) and trained about potential hazards.
  • Have an arc flash hazard assessment completed by a qualified professional to identify arc flash hazards, potential energy release, arc flash boundary, and what protective measures are required (such as PPE) at each point in the system. The assessment should be updated any time the electrical distribution system is modified, or at least every five years.
  • Label electrical equipment in accordance with NEC requirements and NFPA 70E guidelines.
  • Follow preventative maintenance requirements of NFPA 70B and equipment manufacturers.

Barton Associates has performed power systems studies on all types (whether brand new facilities or aged infrastructure) and sizes (from small standalone retail spaces to full higher education or healthcare campus complexes) of projects and is ready to help you with any questions or needs you may have. For information on coming into compliance, updating existing studies, or a new analysis of electrical infrastructure, please contact Wes Stiles, PE at

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