1. n. [Drilling]
An electromechanical device used to connect an electrical toolstring to a logging cable, electrical wireline, or coiled tubing string equipped with an electrical conductor. It provides attachments to both the mechanical armor wires (which give logging cable its tensile strength) and the outer mechanical housing of a logging tool, usually by means of threads. This connection to the logging tool results in a good electrical path from the electrical conductors of the logging cable to the electrical contacts of the logging too, and shields this electrical path from contact with conductive fluids, such as certain drilling muds. The basic requirements of most cable heads include providing reliable electrical and mechanical connectivity between the running string and tool string. Another attribute of cable heads is that they serve as a "weak link," so that if a logging tool becomes irretrievably stuck in a well, the operator may intentionally pull in excess of the breaking strength of the logging cable head, causing the cable to pull out of the cable head in a controlled fashion.