This one was NOT wired up correctly.

Brown is the hot wire, blue is neutral. But what do we find? Brown --> N, Blue --> L

Why is this bad? Screwing in a light bulb puts you in danger of getting a shock, as the hot wire is connected to the large metal part of the E27 of the light bulb first. Initially that part is partially exposed. Not good.

I didn't fake the image, I only increased the contrast around the letters.

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ALWAYS TURN OFF THE MAINS POWER IN THE BREAKER-PANEL BEFORE YOU STICK YOUR FINGERS IN. MAKE SURE IT STAYS OFF!