Concerned electricity officials say the raiders risked instant death to break into the 33,000-volt substations.

The raiders caused damage which is likely to cost power giant EDF Energy Networks more than £5,000 to repair.

After one raid, 1,910 customers in Farcet, near Peterborough, were without power for about 20 minutes, from 1.40pm on Tuesday, while officials worked to repair the damaged caused by the thieves.

The following day, in Windrush Drive, Paston, Peterborough, a further 141 customers were without lighting and heating for two hours, from 6pm, while repair works were carried out to another substation.

Later the same evening, another 285 residents were without power for 30 minutes, from 10pm, after a substation was raided.

An EDF Energy Networks spokeswoman said, despite numerous warnings about the dangers of tampering with electrical equipment, such as overhead lines and substations, the number of cable thefts had continued to rise.

She said: “On October 7 and the next day in the Paston Ridings area of Peterborough, essential safety equipment was discovered to have been stolen from at least seven substations.

“In some cases, EDF Energy Networks engineers were able to replace the equipment stolen without affecting supplies to customers.”

She added: “Anyone who tampers with our electrical equipment is risking their lives and those of others.”

The spokeswoman said the firm was working closely with the police to trace and prosecute the thieves.

She said EDF had also embarked on work to step up security at its substations.

Pc Bob Stewart, who covers the Peterborough North East area, said: “To repair a substation requires a member of the EDF Energy staff to deal with high voltages of power, and although these staff members are trained to do this, we all know that accidents can happen, and, in this case, should one occur, then it would result in serious injury or worse.”

He added: “Anyone who sees people attempting to gain entrance to the substation or anyone in the substation compound should contact the police immediately.”

n Anyone who has any information about the break-ins should call police on 0845 456 4564, or EDF Energy Networks on 0800 5873243.