(1) With [[SP]] and [[resistivity]] logging. It is the conductor line, to which is attached a portable surface [[electrode]], which is extended to some remote location from the rig and logging unit to provide electrical ground connection.

(2) With perforation safety. Ground strap. It is a heavy-gauge, low-resistance line provided with appropriate connectors or clamps to electrically connect together the masses of the hoist unit, rig, and [[surface casing]] ([[wellhead]]). This negates voltage differences which may occur between the masses.