An 18-year-old from County Durham was found on fire after trying to steal live electrical cable carrying 11,000 volts, police said.
The teenager, from Darlington, suffered extensive burns to his arms and head during the incident at derelict buildings in Newton Aycliffe.
He was taken to Newcastle's Royal Victoria Infirmary where his condition is described as serious.
A 19-year-old man was arrested and bailed after the incident on Saturday.
Det Insp Simon Orton, of Durham Police, said: "This young man could have died. He will have to live with the consequences of his criminal action for the rest of his life.
"People who go out to steal copper cabling carrying electricity are putting their lives at risk.
"We have had a number of these types of burglaries recently and we want emphasise that the intruders are putting themselves in highly dangerous situations where death could result from dishonesty."