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Grid infrastructureUnited StatesEIR-0840

Underground transformer explosion damages street in Wilmington

June 2017Published 15 Sept 2026Responsible editor: Chief Editor

SignificantElectrical
Estimated damageEstimated by the register's adjusterHow? Know the real figure?
Figure hidden: shown to subscribersMedium confidence
supply cut for about •• daysShown in the record →Full estimate
From the recordFailed part hidden
Where
intersection of 3rd and Monroe streets in Wilmington
Operator
Delmarva Power
What
underground transformer exploded
Cause
Not reported
Outcome
lifted and broke street section, tripped another transformer

Companies named in the reporting of this entry (being named is not a finding of fault): Delmarva Power

What happened

An underground transformer exploded at the intersection of 3rd and Monroe streets in Wilmington, next to the Adams Four Shopping Center, at about 12:30 p.m. on 29 June 2017. The blast lifted and broke up a section of the street around a manhole cover, while the cover itself stayed in place. Delmarva Power reported that the blast tripped at least one other transformer in the Southbridge section and caused a brief power disruption from Pennsylvania Avenue and Rodney Street southwest to Lobdell and Bradford streets. Police and fire services cordoned off the area until crews could assess the vault, and officers directed traffic where signals were dark.

Contributing factors

The cause of the transformer explosion was not reported.

Lessons learned

  1. An underground transformer fault can lift and break the street even when the manhole cover stays in place, so the surrounding pavement should be treated as unstable.
  2. A fault can trip other transformers and darken signals beyond the blast site, so traffic control should follow the reported outage area.
  3. Isolation of the vault and restoration of supply should proceed while the damaged street remains cordoned.

More lessons on outages, backup supply and restoration, electrical protection and isolation, from every incident on the register.

Not yet known

  • Transformer model and age
  • Duration of power disruption
  • Cost of repairs and street restoration

This entry is updated when these are reported. Get an alert for the next one like it.

Source

wdel.com

Published 2026-09-15. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.

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