Cable monitoring system with multiple branch terminations

A method of monitoring a communications cable system comprising a main cable and a plurality of branch cables, each with a detection conductor extending therealong, the detection conductors being electrically connected, and a plurality of branch termination means connected to the respective branch detection conductors at terminal ends of the respective branches, said method comprising:

• applying a voltage to the detection conductor of the main cable;
• actuating the branch termination means with a signal applied to the detection conductor of the main cable;
• causing the branch termination means to connect to ground the individual branch detection conductors individually and at separate times;
• and
• measuring current in the detection conductor of the main cable.

A termination circuit for a communication cable having a detection conductor extending therealong, said termination circuit comprising:

• monitoring terminal means for connecting the termination circuit to the detection conductor;
• ground terminal means for connecting the termination circuit to ground;
• grounding means for producing a resistance path between the monitoring terminal means and the ground terminal means in response to receipt of an actuating signal at the monitoring terminal means;
• and
• means for inhibiting operation of the grounding means and maintaining the termination circuit as an open circuit in response to the monitoring terminal means having a negative potential with respect to the ground terminal means.

A monitoring system for a communications cable system including a main cable with a monitored end and a plurality of branch cables coupled to the main cable at respective splices, each of the main and branch cables having a detection conductor extending therealong, the detection conductors being electrically connected at the splices, said monitoring system comprising means for applying a DC voltage to the monitored end of the main cable detection conductor, a plurality of termination means connected to the respective detection conductors at ends thereof, a plurality of splice sensor units at the respective splices for detecting the presence of moisture at the respective splices and applying encoded signals to the detection conductors, means for monitoring currents in the main cable detection conductor and, means for detecting encoded signals from the splice sensor units, the system being characterized in that:

• each termination means has a non-actuated state maintaining an open circuit to ground and an actuated state connecting the associated detection conductor to ground;
• and
• the system includes actuating means for selectively actuating the termination means to the actuated state;
• and
• each termination means comprises means for applying a coded termination signal to the associated detection conductor in response to actuation of the termination means, and including means coupled to the main cable detection conductor at the monitored end for detecting the coded termination signals.