You perform a butt splice General Wire-Stripping Instructions
Cut back a portion of the outer cover and slide suitable dia heatshrink over the outer sheath, use heatshrink on each of the butt splices then slide the large out piece to cover all conductors.
If it has braid outer, you can often use metal tape or some suitable means of connecting each covering the overall connection.
It is most likely best to cut all conductors through and splice them all.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.