[Hallb-engineering] Fwd: Lesson Learned "Pinched Power Cable Results in Electrical Short and Spark - Argonne National Laboratory"
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Tue Sep 27 06:12:20 EDT 2016
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Subject: Lesson Learned "Pinched Power Cable Results in Electrical Short and Spark - Argonne National Laboratory"
Jefferson Lab Lessons Learned : Print Lesson
Pinched Power Cable Results in Electrical Short and Spark - Argonne National Laboratory
Statement of Lessons Learned
Inspect equipment prior to use to help identify potential hazards and prevent injuries.
Discussion of Activities
At Argonne National Laboratory Alpha Gamma Hot Cell Facility (AGHCF) telemanipulators are used in inert gas environments to perform remote operations when dealing with radioactive material. A common 15 amp 120 VAC outlet provides power to the telemanipulator�s AC/DC power supply via a cord approximately 6 feet long.
On Tuesday, November 17, 2015, an AGHCF technician was performing remote operations using telemanipulators when he heard a popping sound and saw a flash of light overhead. The technician immediately stopped his work and notified his supervisor. Upon investigation, the power cord to the telemanipulaor was found to have been pinched between the Y motion cable�s pulley system causing a direct short and a spark. The equipment was tested and found to be properly grounded, eliminating risk of electrical shock to the operator. To avoid future incidents, the telemanipulator was de-energized and tagged out of service for future repair.
During installation of the master side of the telemanipulator, the power cord was draped over the top of the through tube to prevent it from hanging in front of the operator. The configuration of the cord over the through tube placed it in close proximity of multiple pinch points. The cord eventually managed to work its way into the pulley system for the Y motion cable which resulted in the short.
One of the cable ties used to manage the power cord was missing from the frame of the telemanipulator. The cable tie would have prevented the cord from hanging low enough to be a nuisance to the operator, and may have affected the decision to drape the cord over the through tube during installation.
Telemanipulator operation does not require a prior-to-use inspection. A brief visual inspection of the telemanipulator may have identified the issue prior to the incident and allowed the technician to correct the situation.
The following actions were identified:
1. An extent of condition inspection was performed on all telemanipulators to ensure and correct any other cord draping and to verify that all cable ties werere in place to properly route the power cord.
2. Power cords were shortend or wrapped to prevent them from hanging in front of the operator.
3. Telemanipulator prior-to-use inspection training was required for all AGHCF qualified operators.
4. Replaced the damaged workstation�s power cord.
JLab Preventive Measures
As part of Jefferson Lab�s Work Planning Process safety walk-downs, pre-job-briefings, and equipment inspections are required; our Safety Wardens also diligently perform safety inspect of equipment. This lesson learned shows that small changes in equipment configuration may not be noticed immediately, but over time could cause detrimental effects.
9/26/2016 2:18:28 PM by Bailey, Mary Jo
Submitted to those with Lock, Tag, and Try Training
Summary Lesson ID: 970
Doc ID: 2016-JLAB-970
Safety Related: YES
Originator: Bailey, Mary Jo
Issued: 9/26/2016 2:17:20 PM
Approved By: Bailey, Mary Jo
Approved On: 9/26/2016 2:18:28 PM
Contact: Jimmy Smith, jesmith at anl.gov, (630) 252-8616
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Sent Emails: 0
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