Abstract: A system for protecting the transmission of signals from and/or to a tool in a high pressure environment. The system includes a tool connected to a signal transmission line, such as an electrical cable or optical fiber. The signal transmission line is surrounded by a protective tube that is connected to the tool by a connector having a hollow chamber in communication with the interior of the tube. A fluid, such as a dielectric liquid, is disposed within the connector and the tubing at a pressure higher than the environmental pressure. In the event of a leak at, for instance, the connector, the high pressure fluid flows outwardly rather than allowing the inflow of deleterious fluid from the environment.