What is Arc Flash?
Electrical arc flash is the unexpected release of energy in the form of light, heat, sound, and a blast of arc products that may consist of vaporized components of enclosure material (copper, steel, or aluminum). According to the National Fire Protection Association (NFPA) and the Institute of Electrical and Electronics Engineers (IEEE), 2,000 workers each year are admitted to burn centers for extended injury treatment caused by arc flash.
This NFPA video shows what happens during an electrical arc flash:
If necessary, a copy of the video transcript (PDF) is available.
NFPA standard 70E requires electrical equipment owners to perform arc flash hazard analysis to determine the arc flash boundary, the incident energy at the working distance, and the personal protective equipment (PPE) that workers within the arc flash boundary must use. PPE is not intended to prevent all injuries, but is intended to mitigate the impact of an arc flash, should one occur.
How do we avoid Arc Flash at UT Austin?
The university takes multiple precautions to avoid arc flash:
- Trained facilities personnel should de-energize the equipment affected and perform proper lockout/tagout procedures whenever possible.
- Energized work is prohibited on exposed electrical parts with nominal voltage of more than 50 volts, unless workers are conducting testing or trouble-shooting where de-energizing is not feasible, or unless de-energizing the part(s) will create a greater hazard.
- Only qualified persons shall be permitted to work on electrical conductors or circuit parts that have not been put into an electrically safe work condition.
- Those working on or near exposed energized electrical parts shall use appropriate personal protective equipment (PPE) and tools to protect themselves from potential electrical shock, arc flash, and fire hazards.
What is Arc Flash Analysis?
Arc flash analysis is a technical study investigating a worker’s potential exposure to arc flash energy. The study is prepared by an electrical engineer and conducted for the purposes of injury prevention and determination of safe work practices, arc flash boundary, and appropriate levels of personal protective equipment (PPE).
The arc flash analysis must be updated when a major modification or renovation takes place. It must be reviewed periodically, not to exceed five years, to account for changes in the electrical distribution system that could affect the results of the arc flash hazard analysis.
The arc flash hazard analysis and recommended PPE levels are no substitutes for safe work practices. Certain burn injuries can occur even when adequate PPE is employed, and the recommended PPE may provide little or no protection against arc blast and its effects when circuits or equipment have not been placed in an electrically safe work condition .
Why is the program required?
The Facilities Operations and Maintenance division of Facilities Services has been charged with developing an Arc Flash Analysis Program (AFAP) on behalf of the university. The program was established to develop the standard procedures for the implementing of and continuing compliance with the national and industry standards governing electrical safety.
The guidelines for work involving electrical hazards and the selection of arc flash protective equipment are provided by National Fire Protection Association (NFPA) standard 70E. This standard requires electrical equipment owners to perform arc flash hazard analysis to determine the arc flash boundary, the incident energy at the working distance, and the personal protective equipment (PPE) that employees within the arc flash boundary must use.
The arc flash analysis must be updated when a major modification or renovation takes place. It must be reviewed periodically, not to exceed five years, to account for changes in the electrical distribution systems that could affect the results of the arc flash hazard analysis.
Institute of Electrical and Electronics Engineers (IEEE) standard 1584 provides the standard for calculating arc flash energy levels at different points in the electrical power system.
Progress at UT Main Campus
Progress on Arc Flash Analysis on the university's Main Campus is detailed in a quarterly report, prepared by the AFAP team.
National Fire Protection Association (NFPA) standard 70E states that, when necessary, labels must be posted on special equipment to "warn employees about electrical hazards that might endanger them." In compliance with the standard, the university requires the following information for arc flash labels posted on identified equipment:
- Equipment designation
- Nominal voltage
- Flash protection boundary
- Hazard risk category
- Incident energy
- Working distance
- Personal protective equipment required
Here is an example:
Roles and Responsibilities
FOM - Arc Flash Analysis Team:
- Implement arc flash studies that are lacking on existing buildings at the university's Main Campus and J. J. Pickle Research Campus.
- Maintain copies of documents and electronic files for site studies. This includes copies of all short-circuit coordination studies, arc flash studies, and single-line diagrams, as well as documentation on subsequent electrical system changes.
- Implement a five-year electrical single-line (power-flow study) review.
Shop Supervisors / Trade Leaders:
- Ensure respective employees comply with all provisions of the Arc Flash Analysis Program.
- Ensure respective employees are trained in arc flash and electrical safety.
- Assist arc flash analysis team in a five-year review and update of existing arc flash analysis.
- Report to the Primary AFAP Engineer any discrepancies between field conditions and the single-line diagram created with SKM Systems Analysis, Inc. (SKM) electrical engineering software.
- Coordinate with the Primary AFAP Engineer to maintain up-to-date single-line diagrams, panel schedules, and SKM models.
- Include a review of the arc flash study in any major modification or renovation to the electrical system of a building.
- Deliver reviewed and completed SKM files and other electrical power system documentation to the Primary AFAP Engineer as part of the project sign-off.
AFA in Project Management - Flow Chart
View a flow chart (PDF) that illustrates the process for determining when project managers should incorporate arc flash analysis into the scope of projects at the university. Additional information, including the full standard operating procedures (SOP), can be found here (PDF).
For questions or additional information about the university's Arc Flash Analysis Program, contact:
Arc Flash Engineer, Engineering & Technical Support, FOM, Facilities Services
Manager, Engineering & Technical Support, FOM, Facilities Services
Master Electrician, Engineering & Technical Support, FOM, Facilities Services
James A. Smith
Manager, Facilities Services Safety