About 30,000 homes were left without power after metal thieves ransacked one of the West Midlands’ main electricity sub-stations for the third time in days.

They escaped with thousands of pounds worth of copper from the 132,000-volt sub-station in Walsall, following the latest bid by crooks to cash in on rocketing metal prices. 

Homes in Walsall, Great Barr, Wednesbury and West Bromwich had their power cut for 30 minutes last night from 7.50pm, meaning many TV viewers missed the end of the first part of Coronation Street.

Central Networks spokeswoman Emily Highmore said: “It absolutely beggars belief that people would go into a high-volt sub-station like this and risk their lives.

“It happened twice over the weekend, and then again last night, and next time it could be two bodies we discover in there.

“I can’t believe people don’t realise the dangers; there are signs outside all of our sub-stations saying ‘risk of death’. People are warned, and yet they keep going in anyway. 

“They are basically trying to steal copper and tampering with our equipment, so even if they get out alive, it makes it incredible dangerous for our workers to go in afterwards and deal with the problems.”

The sub-station – the exact location is not being revealed – is now under surveillance.

West Midlands Police launched Operation Steel in August 2007 to tackle the rising number of metal thefts, particularly involving lead or copper, on the western side of the force area.  To date, more than 600 people have been arrested.

Thieves have raided schools and graveyards around the Black Country, in a bid to steal metal to sell on as scrap, and have taken entire bus shelters and door knockers.

And last month, vandals pilfered commemorative plaques in Smethwick and Tipton that had been bought by residents as a tribute to the pottery and chainmaking industries.