Underground transformer explosion damages street and cuts power in Wilmington

An underground transformer exploded at the intersection of 3rd and Monroe streets in Wilmington, Delaware, next to a shopping centre around 12.30pm on 29 June 2017. The force of the blast lifted and broke up a section of the street around a manhole cover, an unusual outcome since such events typically blow the cover off instead. Wilmington police and firefighters cordoned off the area until Delmarva Power crews arrived to assess the underground vault. The blast also tripped at least one other transformer in the city's Southbridge section, causing a brief power disruption across several streets. Traffic signals at two intersections went dark, requiring police to direct traffic manually. Injuries were not reported by the source.

Not reported. The source does not state the cause of the transformer failure.

1. Underground transformer vaults should be designed and maintained to manage pressure release safely during equipment failure, including the risk of surface displacement as well as ejected covers.
2. Utilities should have arrangements with local police and fire services for rapid cordoning of streets when underground electrical equipment fails.
3. Contingency plans for darkened traffic signals should be in place, because a single vault failure can trip adjacent transformers and extend the affected area.

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