Worker Experiences Electric Shock While Plugging Container

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The German Federal Bureau of Maritime Casualty Investigation (BSU) published an incident report in which a worker experienced electric sock while plugging a container into a socket in during August of 2020 in Hamburg.

The incident

An incident involving personnel occurred on board the fully-containerised vessel MONTREAL EXPRESS at 20063 on 29 August 2020. At this point, the ship was at its berth in the port of Hamburg for cargo-handling operations.

A dock worker had intended to connect a refrigerated container stowed on deck in the area of bay 38/39 to the ship’s power supply system. To this end, he went to the nearest terminal/switch box with the plug of the power cable, which was fitted to the container in the usual manner. This was located on the port side of the ship below the hatch coaming in the area of bay 39.

There was a sudden flash of light when the dock worker was inserting the cable’s plug into the socket. He felt a mild electric shock but was able to leave the scene unassisted and report the occurrence to his supervisor. The latter immediately called an emergency physician and notified the ship’s command and Waterway Police (WSP) Hamburg.

The crew of an ambulance was at the scene just a short time later and examined the dock worker, who exhibited no injuries but was in a state of shock. He was taken to hospital for further observation as a precaution but was able to leave it soon after. Apart from him temporarily being in a mild state of shock, the incident did not give rise to any adverse health effects.

Why did it happen?

  • The rubber seal of the switch box housing, which was firmly closed with a screwed cover, was damaged and therefore insufficiently preventing the ingress of moisture.
  • This could lead to the formation of a so-called creepage distance formation in the housing, which could trigger a fault current.
  • The PE conductor (earthing connection) was severely impaired in its functionality due to corrosion and/or loose contact.
  • The fault current caused by the creepage distance was therefore not (exclusively) discharged directly via the PE conductor in the direction of the ship’s hull. Instead, the fault current flowed at least partially through the body of the dock worker during contact with the switch box housing, who suffered an electric shock as a result.

What can we learn?

Random checks on board the ship revealed that other terminal/switch boxes had similar defects. In the course of the investigation, the BSU received knowledge of further incidents resulting in health hazards of dock workers connecting refrigerated containers on five different container ships of other shipping companies in the port of Hamburg. Fortunately, what all cases had in common was that the affected persons did not sustain serious injuries. It can therefore be assumed that dangerous incidents frequently occur in ports around the world in connection with the connection of reefer containers, but that these are not reported due to their mild outcome and are therefore not investigated in depth. This in turn is probably a decisive reason why the on-board inspection and maintenance of the relevant equipment, as well as its random inspection by classification societies and authorities, do not seem to have the importance they should have in relation to the serious dangers that can emanate from defective electrical equipment.

Recommendations

  • Planning, implementation and documentation of regular inspections of the technical condition of all terminal/switch boxes for refrigerated containers by the relevant qualified technical personnel on board.
  • Inclusion of the inspection routines in the ship’s maintenance system.
  • Immediate decommissioning of defective terminal/switch boxes until they have been professionally repaired.
  • Inspection of the terminal/switch boxes by a shore-based service company at fixed intervals.
  • Greater consideration of the (random) inspection of the technical condition of reefer container terminal/switch boxes when surveys are carried out by the classification societies and during Port State Controls.

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Source: German Federal Bureau of Maritime Casualty Investigation (BSU)