Power downhole tool via a powered drill string

The disclosure is directed to a method and system to provide electrical current to a downhole tool, such as an active magnetic ranging tool. The electrical current can be transmitted through a drill string, with an end attached drilling assembly inserted into a wellbore. The downhole tool can include a power isolation sub to create an isolated electrical zone along the drill string. The downhole tool can transmit an electrical current along a designated portion of a subterranean formation to create a resultant magnetic field to be detected by the active magnetic ranging tool or other downhole tools. A drilling wellbore can maintain drilling operations while actively ranging a target well for intercept and other operations. The drilling assembly does not need to be removed from the wellbore to enable the activities of the active magnetic ranging tool, and access to the target wellbore is not needed.