Electrical Arc Flash Accident Investigation

 

Following are excerpts from the Type A Accident Investigation by the U.S. Department of Energy of an Electrical Arc Injury on October 11, 2004 in Menlo Park, California.

Click here, or click on the image to read the Investigation in its entirety (this may take some time to open: it is 80 pages, 5.3MB). At the end of this article we have some links to other reported incidents and to some educational resources.

EXECUTIVE SUMMARY
The Accident
On October 11, 2004, at approximately 11:15 am, a subcontractor electrician working at the Stanford Linear Accelerator Center (SLAC) received serious burn injuries requiring hospitalization due to an electrical arc flash that occurred during the installation of a circuit breaker in an energized 480-Volt (V) electrical panel.

Analysis and Results
The accident resulted from deficiencies in SLAC’s work control planning and implementation processes. The Site Engineering and Maintenance Department (SE&M) exhibits a culture where safety is often secondary to operations. The Board identified deficiencies in the line management organizations of the DOE Stanford Site Office (SSO), SLAC, and Bay Span, Inc. (Bay Span), the electrical subcontractor performing the work.

The events leading up to and during the installation of the circuit breaker and the resultant arc flash are characteristic of an unstructured and largely undocumented approach to work that does not ensure the safety and health of workers at SLAC. Managers, supervisors, and support staff do not take action to enforce compliance with the safety requirements for this very dangerous task. For the circuit breaker replacement, the Board identified the following key deficiencies:

• A “Pre-Work Hazard Analysis” (PWHA) form was not completed.
• There was no approved electrical hot work permit.
• The workers were not wearing the appropriate Flame Resistant (FR) clothing and all the required Personal Protective Equipment (PPE).
• The Bay Span Laborer (BSL) was not trained to be backup for an electrician.
• No one in the SLAC management chain had been informed of the decision by the SLAC Field Supervisor (FS-1) to install the circuit breaker in an energized panel.
• SLAC safety officials were not involved (only notified after such work occurred).

All SLAC management officials above FS-1 stated that it was unnecessary for the circuit breaker installation to be done with the panel energized, and they would not have approved working on an energized circuit breaker panel. The events that occurred on October 11, 2004, violated all of the Integrated Safety Management (ISM) Guiding Principles and Core Functions.

Conclusion
The Board concludes that this accident was preventable. The direct cause of the injury was an explosive release of energy resulting from an arc flash that occurred during the installation of a circuit breaker in a 480V energized panel. The circuit breaker installation on an energized panel was not justified. If proper permitting procedures had been followed, the work would not have been performed. The severity of the injuries could have been significantly reduced or eliminated had the worker been wearing the appropriate FR clothing and using the correct PPE. There were at least three people directly involved in the task with sufficient direct interaction and safety knowledge who could have exercised stop work authority because of the unsafe working conditions, yet no one took action.

 

Other reported incidents:

Brookhaven National Laboratory Arc-Flash Incident: http://www.bnl.gov/esh/shsd/ESH%20Coordinator%20Presentations/2006-0927/Type%20B%20JON%20-%20Sandberg.pdf

Arc Flash Incident Palo Verde, Arizona 2008: http://www.youtube.com/watch?v=8hO1s_SFHe0

Wood River substation incident: https://www.storesonlinepro.com/files/2304822/uploaded/Chevron%20Incident.pdf

 

Some websites to visit for information on preventing arc flash incidents:

Emerson Process Management’s FAQs on Arc Flash Solutions:http://www.electricalreliability.com/ArcFlashFAQ.htm

ESA’s Arc Flash Resource Center: http://easypower.com/arc_flash/arc_flash_resource_center.php

Arc Flash Information Resource: http://www.arcflash.me/arc-flash-safety.php

National Institute for Occupational Safety and Health: http://www.cdc.gov/niosh/mining/products/product152.htm

ESPS Electrical Safety Program Solutions, Inc: http://www.esps.ca/Default.aspx?cid=222&lang=1

High Voltage Info: http://www.highvoltageinfo.com/arc-flash-video.php