Joining 8 wires into one
You should be looking for something like an IP65 weatherproof junction box.

The designs vary from country to country (as do regulations of course) so it's hard to be more specific.



Ideally you want a bus type connector that has separate connection points for each wire. A single screw-terminal probably can't securely hold so many wires.


Example WAGO 8-way push fit connector and 5-way lever-clamp connector (400V 32A max)