Task: Operating high voltage switchgear equipment
Injury: Electrical shock
This advisory is to inform pipeline companies who operate and maintain high voltage switchgear equipment, of a potentially dangerous situation related specifically to the following equipment - Square D Isoflex Model 5 Motor Control Center, 5 KV.
Description Of Incident:
Recently, an electrician from a construction contractor was injured while doing work on this type of equipment at a facility in Canada. The load side of the motor starter cell was isolated prior to the commencement of work. A bolted access panel was removed from the top portion of the motor starter cell in order to facilitate removal of the motor feed cables that ran from the motor starter. The electrician received an electrical shock as a result of making contact with a live 2400 volt surge arrestor while removing the motor feeder cables.
The surge arrestor did not appear on the vendor drawings that were supplied with the equipment at the time it was originally installed and was concealed behind a bolted access cover in the top portion of the cell; consequently, the surge arrestor was not identified as a potential energy source and was not de-energized during the initial isolation that occurred prior to the commencement of work.
By manufacturer's design, the compartment behind the bolted access cover contained both load and line side conductors and there were no barriers between the two. The surge arrestor was connected to the line side of the cell and was installed in a common compartment with the motor feeder cables (load side conductors).
No warning label was provided on the bolted access cover that was removed and no protection caps were installed on the surge arrestors at the time of manufacture.
The hazard associated with the surge arrestor was not adequately re-assessed upon becoming aware of its presence following the removal of the bolted access cover.
The surge arrestor was not tested to confirm that it was de-energized prior to proceeding with work.
The following picture illustrates the location of the surge arrestor within the top portion of the switchgear cell.
Supervisor of Construction & Records Services
Phone: (780) 420-8747