Emergency services were called to the junction of Corser Street and Willenhall Road at around 9.40pm on Tuesday to reports that a 28-year-old man had suffered serious electrical injuries following a break-in at an electricity substation at a former British Steel site.
The man remained in a critical condition in hospital today.
Police believe he may have been with two other men, who left the scene when paramedics arrived.
Inspector Kate Longbottom, from Wolverhampton CID, said: “We believe that the injured man was using cutting equipment and came into contact with a live wire.
“We really need to trace the other two men who we believe left the scene when paramedics arrived.
“We also need to hear from anyone who may have seen anything suspicious in the area at the time to get in touch with us.”
A spokesman for West Midlands Ambulance Service said: "We were called at 9:30pm on Tuesday to Corser Street in Wolverhampton. We sent one ambulance, two paramedic officers and the MERIT emergency doctor and critical care paramedic to the scene.
"Crews treated one patient, a man, for serious injuries and he was taken to hospital on blue lights and sirens for further treatment with the MERIT team onboard.”
Anyone with information is asked to call West Midlands Police on 101, quoting incident number 4938 of November 24.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org