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Grid infrastructureUnited KingdomEIR-0770

Substation equipment failure near Truro causes widespread power flickering in Cornwall

Dec 2023Published 15 Sept 2026Responsible editor: Chief Editor

SignificantElectrical
Estimated damageEstimated by the register's adjusterHow? Know the real figure?
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supply cut for about •• daysShown in the record →Full estimate
From the recordRoot cause hiddenFailed part hidden
Where
Substation off the B3284 between Truro and Shortlanesend, Cornwall
Operator
National Grid
What
Piece of plant failed after maintenance, causing voltage dip
Cause
Not reported
Outcome
Brief interruptions affected thousands of properties

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

What happened

Following maintenance work at a National Grid substation located off the B3284 between Truro and Shortlanesend, Cornwall, an incident occurred after the network had been restored to normal working. A piece of plant failed, producing a bright flash that was reported by local residents as explosions and fireballs visible from as far away as Falmouth. The failure caused a dip in voltage across a wide area of Cornwall, resulting in flickering lights and brief power interruptions affecting thousands of properties from Bodmin to Penzance, including Truro city centre where some Christmas lights and shop lighting were briefly affected.

No property appears to have lost power for more than a few seconds. National Grid confirmed the substation as the source of the disruption and stated that repair work resumed the following morning.

Contributing factors

The failure occurred shortly after maintenance work at the substation had been completed and the network restored to normal working, with a piece of plant subsequently failing.

Lessons learned

  1. Substation plant should be monitored immediately after restoration to service, as failures can occur even after maintenance appears complete.
  2. Visible flashes or bangs at substations can alarm the public, so operators should issue prompt clear statements.
  3. Voltage dips from substation failures can affect wide areas, so operators should check customer resilience to brief disturbances.

More lessons on detection and monitoring, from every incident on the register.

Not yet known

  • Exact cause of the plant failure
  • Type and age of failed equipment
  • Duration of repair work
  • Cost of the repairs

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

Source

cornwalllive.com

Other entries that name Cornwall

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

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