These are the wires I found in my ceiling :
I couldn't identify the color code (we live in the UAE, so there is no "natural" convention, and I'm used to EU convention).
There is tension (voltage) between the yellow wire and the other ones, but not between the blacks and green-yellow, so I assume yellow = phase.
Q1: Is it safe to assume that yellow-green = earth and black = neutral? If not, is there a way to check?
Q2: Why two earth and two neutral wires?
Q3: How should I connect my (very basic) roof light?