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?


  1. If you have a house wide ground fault current interrupter then you could connect a lamp across the yellow and green and see if it trips.

  2. Your box has 3 inputs, the black and green both come from the left and bottom (in your picture) while the yellow comes from the right. Presumable to switches and other lights. They are meant to be connected together either in a pigtail or in the fixture if the connection is rated for multiple wires.

The color code looks to be "UK prior to 2004" based on this page, which is consistent with the fact that the building predates 2004 and that the UAE often uses British standards.

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  • 1 > Good point, will try. 2 > Sorry, I didn't get it. Are the two pairs of neutral/ground supposed to connect to the same one phase? – Alexandre Halm Nov 20 '15 at 9:17
  • OK get it. Re: the pigtail, shouldn't there be a second phase wire (maybe it's hidden in the box)? – Alexandre Halm Nov 20 '15 at 9:46
  • @AlexandreHalm there is a yellow going from left to bottom, I believe that is the phase that goes with those black an greens. – ratchet freak Nov 20 '15 at 9:48
  • Green with a yellow stripe is a standard ground color in Europe/Germany if that helps. You could get a better idea what they did by removing the cover to the main panel to see where these wire colors are terminated. This is something that should be done with great care preferrably by an experienced electrician. – ArchonOSX Nov 20 '15 at 10:48

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