Pole fire on 33 kV line shuts M5 and trips supply in Burnham-On-Sea

What happened

On the evening of Wednesday 8 July 2020, a pole carrying a 33,000 volt line near the M5 at Burnham-On-Sea caught fire. Western Power Distribution said the line was the 33,000 volt circuit feeding its Burnham Primary Substation. The top of the pole burnt off, which let the conductors clash together, and at 6.55pm the circuit breaker feeding the substation tripped, disconnecting 10,546 customers. Most were restored at once through an alternative circuit.

The M5 was closed in both directions between Bridgwater and Burnham-On-Sea from 7pm until 3.45am. Two fire engines from Bridgwater and one from Burnham attended. The fire service said the pole fell because of the fire damage, the fire burnt out naturally, and the scene was handed to Western Power and Highways England. The cause was not known and the fire was treated as accidental. The report did not mention any injuries.

Contributing factors

The cause of the pole fire was not known. The top of the pole burnt off, letting the conductors clash and trip the circuit breaker.

Lessons learned

1. A failed overhead line pole beside a motorway can close the road as well as trip supply, so operators and highway authorities need a practised way to isolate the line and manage the closure.
2. An alternative feed restored most of the 10,546 customers at once, which shows the value of a tested second supply route into a primary substation.
3. Where the cause of a pole fire is not known, the damaged pole and fittings should be examined before the line is returned to service.

Source

burnham-on-sea.com