The contractor was siding a home in the 1500 block of Bonwood Road in the Alban Park section of Wilmington when he lost his balance.
It is not known yet if he came in contact with overhead electrical wires.
When firefighters arrived on scene, the victim was in cardiac arrest.
Firefighters worked to revive the contractor by performing CPR.
The contractor, said to be around 50 years old, was taken to Christiana Hospital in critical condition.
