This article was posted 10/19/2009 and is most likely outdated.

Arc Flash Incident - No Loss
 

 

Topic - Safety
Subject - Arc Flash Incident - No Loss

October 19, 2009
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Arc Flash Incident – No Loss


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Enform Canada recently reported on this arc flash incident which occurred when a technician touched two exposed lugs of a 480-volt main breaker. No injuries resulted.

 

Safety Alert # 13-2009
Arc Flash Incident - No Loss
Release Date: September 14, 2009


 Function: Drilling Rig

 Incident Date: April 23, 2009

 Incident Type: Non Injury

 Country and Region: Western Canada

Summary:
An arc flash occurred when a technician touched two exposed lugs of a 480-volt main breaker in a Motor Control Center (MCC) while performing maintenance checks.
 
Description of Incident:
During the course of commissioning a new 480v MCC, a contact technician was required to perform phasing checks on the exposed lugs on the line side of the 480v main breaker. The technician was using a commercially available set of phase sticks with a shepherd-hook style end. When the technician attempted to check the phase C lug, the hooked end of the phase stick came in direct contact with both B and C phase lugs. Spacing between the lugs was approximately 1”. As per manufacturer’s specification for this voltage, there were no barriers between the lugs. The resulting contact cased an arc flash.
 
While the worker was not injured, there is potential for an arc flash to cause serious burns. Explosive arc blasts can also occur causing damaging sound levels and exposure to a high pressure blast which could cause eardrums to rupture and lung damage.
 
Important investigation results identified that:
• An arc flash hazard study had been conducted on the MCC. The equipment involved in the incident was rated and required Category 2 personal protective equipment.
• The technician was wearing the required arc flash rated PPE
• The technician thought that because the breaker was tripped, the lugs were de-energized.
• In an attempt to demonstrate what happened, the technician, placed the phase stick back into the breaker cabinet and caused a second arc flash. The technician thought that because the breaker had been tripped that the lugs were de-energized. 
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Causal Analysis:
A detailed incident investigation was completed. The main causal factors were:
• The contactor’s safety management process did not identify the training standards and procedures required for contractors to perform critical work.
• The contractor’s standards did not address the hazards of working on exposed 480 volt terminals, barriers and breaker configuration for phase checking.
• The process of training electrical workers to become “qualified” and understand the hazards associated with arc flash were not well defined nor applied consistently with new workers.
• The ‘sheppards’ hook style phase stick was designed for overhead lines and was not the appropriate equipment/tool for checking this equipment.
• Hazard identification and controls were not implemented even though the work involved energized electrical parts.
• A Field-Level Hazard Assessment (FLHA) was not conducted prior to completing the phase checks to identify the hazards of performing this job.

We Can Prevent Similar Incidents:
This incident reinforces the importance of the fall protection requirements identified in occupational health and safety regulations. In this case, the employer identified the following corrective actions:
• Review and enhance contractor selection process to ensure that training standards and procedures have been established for electrical contractors performing
• Develop an Arc Flash Hazard Study standard consistent with industry standards. Ensure that all analysis are conducted in accordance with this standard and that the results are communicated to personnel performing maintenance work.
• Revise/enhance Company standards and training program to address arc flash and electrical shock hazards.
• Work on high-voltage electrical equipment is a critical task and requires that a Field-Level Hazard Assessment (FLHA) be completed before beginning work. Additional Information: In addition to the Canadian Electrical Code (CSA C22.1-09), other relevant references include:
• NFPA 70E-2000 Standard for Electrical Safety Requirements for Employee Workplaces.
• IEEE Standard 1584-2002 Guide for Performing Arc Flash Hazard Calculations
Contact:
safety@enform.ca  


DISCLAIMER:
This Safety Alert is designed to prevent similar incidents by communicating the information at the earliest possible opportunity. Accordingly, the information may change over time. It may be necessary to obtain updates from the source before relying upon the accuracy of the information contained herein. This material is presented for information purposes only. Managers and supervisors should evaluate this information to determine if it can be applied to their own situations and practices

 

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Comments
  • "In an attempt to demonstrate what happened, the technician, placed the phase stick back into the breaker cabinet and caused a second arc flash. "

    Well, as if the tech did not learn his lesson first, he proceeds to create another arc. He should be fired.

    Eric Scott PE
    Reply to this comment

  • It sounds like the person doing the work WAS NOT qualified to perform that kind of work since he did it twice the way I understand from what I read.If he had the right PPE on why would he be using a hot stick anyway .

    Duane Boysen
    Reply to this comment

  • In the references section NFPA-70E-2000 is cited. THe latest version of this Consensus Standard is NFPA70E-2009.

    Blaine Bunch
    Reply to this comment

  • training, training ..training. phase stick? I wounder how many more safety rules these incidents will cause. no more hot work?

    I am human I make mistakes and must be careful

    peteb
    Reply to this comment

  • He did it twice? Let's think here....main breaker. I am glad that he was wearing PPE. Inappropriate assessment does cause accidents. Another pair of eyes and another persons brain to share thought with is always a good idea. Arc flash can also cause eye damage.

    Chuck
    Reply to this comment

  • We had a guy who airnailed his foot to the floor. Two months later when he came back to work, someone asked him "How did it happen?" "Like this!" he said, and airnailed is foot to the floor again. True story.

    Lawrence
    Reply to this comment

  • I am a bit disturbed that "This incident reinforces the importance of the fall protection requirements". CLEARLY fall protection did not play a part in this accident. I am an advocate of fall protectection and it's enforcement but moreover I dislike safety personel from doing a "cut and paste" to describe a very serious incident.

    Doug
    Reply to this comment


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