How can I install a branch on a wire?

If you need to keep the cable and do not plan to cut it, it is better to use branch connectors ОВ or OB-T made by KBT. An additional advantage of nylon branch connector OB-T is that you can leave the cable without further connection until the time when the connection will be necessary by simple input of a wire ended with nylon-insulated male disconnector РПИ-П(н).
If cutting off the wire is possible in your case, you can also use a branch disconnector with female socket and male plug РПИ-О made by KBT.