As the technician reinserted the standby motor starter (bucket) the wires which were previously attached to the fuse switch became energized and an arc flash occurred resulting in the technician suffering minor reddening to the side of his face.
1. Electrical Arc Flash Incident
Location: Humber Refinery Date: July 10th, 2013
Contact: Lynn Hawthorne Risk Rank: III Impact # 216825
Type of Incident: Near Miss
Incident Description:
On July, 10th 2013, a Shift Power & Control Technician was called to a fault on a 415 Volt motor for a Sulfuric Acid Pump.
Normally the standby pump would be brought into service; however this was out of service for mechanical repairs.
The Technician proceeded to isolate the equipment and withdrew the motor starter (bucket) from the MCC for fault finding.
During the investigation the technician identified that the fuse switch had failed. To expedite the repair, he decided to use
the fuse switch from the standby pump motor starter (bucket), which was out of service. He withdrew the stand by pump
motor starter (bucket) and transferred the fuse switch into the original motor starter (bucket).
The repaired motor starter (bucket) was returned to service and the Sulfuric Acid Pump successfully re-streamed.
The technician planned to mark up the standby motor starter bucket and leave a message for the area electrical technician.
However he noted that with the starter (bucket) withdrawn, the MCC panel could not be locked off as it relied on the fuse
switch on the motor starter (bucket) for this and that there was a large opening in the front of the MCC panel where the
intelligent control unit slotted through, when the drawer was inserted. Not wanting to leave the system unsecure, he decided
to re-insert the standby motor starter (bucket), forgetting that he had removed the fuse switch.
As he reinserted the standby motor starter (bucket) the wires which were previously attached to the fuse switch became
energized and an arc flash occurred resulting in the technician suffering minor reddening to the side of his face. The arc self
extinguished once the ends of the wires had burnt back.
The motor control centre was new and had been built to the latest International standard for arc fault containment; as such
the wearing of Arc Flash PPE was not a site standard for this activity.
Incident Learnings:
By removing the fuse switch the technician created a fault in the motor starter (bucket) which resulted in an arc
flash when it was incorrectly returned to its service position.
The technician failed to realise that the motor starter bucket of the sister pump was identical and could have been
swapped without the need to remove individual components.
The site arc flash policy did not consider faults introduced during maintenance activities, Arc Flash PPE is now a
requirement for this type of task
Motor Starter (Bucket) installed Damaged Motor Starter (Bucket) removed
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