UNDERGROUND CONSTRUCTION
JOINTING CABLES

Cables are jointed together to either extend the cable or two join a number of cables to one cable. Through joints would normally be done on Main Cables, due to the distances though travel either to the Pillar or between exchanges.

The local Distribution Cables generally had joints to join a number of cables radiating towards the DP's or customers premises.

Jointing the wires also changed through the ages. Originally the wires were insulated by paper and they were joined by twisting together and then covered with a paper tube. Plastic insulation was then used but the wires were still twisted and covered with a grease filled tube. Finally, plastic insulated wires where joined by crimps, which were in themselves insulated.

Due to the numerous types of cable sheathes, closure of the joints differed as the sheathes had completely different properties to each other.

Polythene cable jointing using crimps - Lines, Underground F9216

Jointing various sized paper insulated wires
The first three are small gauge are just twisted and then the sleeve is pushed over the joint
The last three wires are larger and are jointed by soldered sleeves, with the paper sleeve covering the joint