0,05mm² wire for Relay

Hi.
I connected Relay on my Light Switch and now I can make it on/off with my Arduino. Lenght of wires is 8m. Is the wire too small for that? Im not really sure current/cross_section_area ratio...

Is the wire connecting the Arduino to the relay or the relay to the light?

Wire is for 5V supply for Relay and signal from Arduino to Relay. So Relay-Arduino. For Light I'm using 1.5mm²

I connected all that and it is working. But sometimes it happens that i can turn the light on. I pressed the button and light is on like a ms that it is off. And latter comes ON on it self. Dont really now why is that