NTSB Issues Recommendation to Address Electrical Hazards on Washington’s Metro System NTSB

NTSB Issues Recommendation to Address Electrical Hazards on Washington’s Metro System

Investigators found that some electrical connections associated with the power supply to the third rail were improperly constructed and installed.

In its ongoing investigation of the Metro train accident at L’Enfant Plaza on Jan. 12, 2015, National Transportation Safety Board investigators found problems with certain electrical connections in Washington’s Metro system that require “immediate action.” The NTSB issued a safety recommendation to address the situation.

Investigators found that some electrical connections associated with the power supply to the third rail were improperly constructed and installed, which can allow moisture and contaminants to enter the components. Such conditions can create the potential for electrical short circuiting, which could result in fire and smoke events in the Washington Metropolitan Area Transit Authority system.

The safety issue was further substantiated during the investigation of the Feb.11 smoke event in the tunnel near the Court House station. Investigators found that cable connectors were missing “sealing sleeves” designed to keep moisture and contaminants away from the high-voltage conductors.

Further, investigators have found instances in other locations in the Metro system where the cable connector assemblies were missing the sleeves. The NTSB has learned that WMATA does not have a program to ensure that the sleeves, which are in its design specifications, are used and installed properly.

To remedy these hazards, the NTSB has asked WMATA to promptly develop and implement a program to ensure that all power cable connector assemblies are constructed and installed in accordance with its engineering design specifications.

“We are hopeful that WMATA management will act on this recommendation in a timely manner so that the hazards we identified can be mitigated as soon as possible," said NTSB Chairman Christopher A. Hart.

Because so much of the evidence in the January 12 L’Enfant Plaza accident was thermally damaged or consumed in the electrical short circuiting event, investigators have so far not been able to determine whether the cable connector assembly was protected by sealing sleeves. The investigation into this accident is ongoing; the findings, safety recommendations and probable cause will be issued when the investigation is completed.

On June 23-24, the NTSB will hold a fact-finding investigative hearing on the January 12 accident in which issues involving WMATA’s programs and maintenance procedures will be explored in detail.

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