How can I make a connection leak-proof?
The easiest way is to use non-insulated ferrules together with adhesive lined heat shrinkable tubes with shirk coefficient 3:1 or 4:1. This method is used for the connection of underwater pumps and in most cases when contact with water is possible. Short recommendations for installation: peel insulation by 1\2 of the ferrule length. Measure and cut a heat-shrinkable tube so that after installation it covers 2-3 cm of cable insulation at both sides, add some length for possible longitudinal shrinkage. Crimp a ferrule with a corresponding tool, put a tube on the place of connection and shrink it with a heat gut. Glue pressed out of the sealed part proves the good leak-proof connection. In case you need more confidence shrink one more heat-shrinkable tube over the first one. The second tube should cover the first one. In case you need a leak-proof connection in cross-section range from 0.5 to 6 mm², use heat shrinkable insulated butt connector ГСИ-Т made by KBT.
If you need a leak-proof connection for cables consisting of 2, 3, 4 or 5 wires, use common insulated butt connectors ГСИ together with adhesive lined heat shrinkable tubes with shirk coefficient 4:1.