Around 1,500 houses in part of Derby have been left without power after vandals attacked electricity cables with an axe.
Engineers said those responsible were lucky to survive damaging the 11,000 volt cable which supplies Spondon.
The cable, targeted where it emerged from underground to run up a pole to a transformer, was found to be damaged on Wednesday evening.
Central Networks said the supply should be restored by Sunday.
Kathy Doyle, from the company, said: "We cannot emphasise strongly enough how dangerous interfering with the electricity supply is.
"Electricity is not a toy, it can cause serious injuries, it can kill. We have a safe network but if people tamper or vandalise it, they risk serious consequences."