Which cable here is the “N” and which is the “L”?All I know is its not the "yellow-green "cable.
Here’s how
They often have L and N marked on it (raised lettering on the plastic) if you look carefully.
It actually does not matter. There is no issue of polarity in a normal light fitting; either way round it gets the same AC supply. That is why it doesn’t bother to mark which is which.
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This. 
Usually the circuit breaker only cuts the L wire. So be careful not to touch the neutral to the earth or you’ll also trip the RCD.
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I can sometimes matter. Newer devices like electric drills use double-pole switches, disconnecting both wires when off. Older appliances, like table lamps, often use single-pole switches that only break the live connection. This means the device can still be live internally when “off” - a risk if you open the casing. Unplugging is crucial to avoid shocks or fires from internal faults. Lamps use screw fittings where the outer metal part is normally neutral and the inner is live. If wired incorrectly, touching the bulb’s metal base while plugged in could cause a shock.
Another story about an elderly woman who was almost killed: A fireman called in an electrician years ago after a woman was severely shocked while taking a shower. The electrician found a dangerous voltage between the showerhead and the drain, and it wasn’t just in the bathroom. Every water fixture in the house was live, which was extremely dangerous.
After hours of searching, the electrician asked the woman if anything had changed in the house recently. She said nothing had happened with the electrical system. But then she mentioned her children had helped her paint the kitchen. The electrician checked out the kitchen and noticed the stove’s clock had reset. When he pulled the stove out, he found the culprit: a non-polarized plug. The neutral wire had been tied to the gas piping as a cost-saving measure, and the live wire was connected to the clock.
The problem came when the stove was plugged back in after the painting was done and it was plugged in backwards. That connected the live wire to the gas piping. Since gas and water lines are often connected in a home, this electrified the entire water system.
I assume the fuse box had not been updated with RCDs in this case?
Note also that RCDs have something like a 5%-10% failure rate, so it is good to be aware of that and test them regularly.
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So you are saying it does not matter. So why does my lamp have the markings “L” and “N” on the socket. Here it does matter.https://www.youtube.com/watch?v=8axvfRoFEVg. (7.04 min)
It would matter if you were wiring more than one lamp in series. It is also good practice (fault tracing, etc)
For all appliances with two pin plugs it does not matter. Light bulbs may or may not have a fitting that determines polarity. Correct wiring of the socket is highly desirable but not always essential for simple function which can lead to the horror stories quoted.
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If it has those markings then I don’t understand why you’re asking the question, Many simple light fittings do not, and it’s that type that I was referring to. No markings==no matter.
Or are you actually referring to the house wiring side of things? They really should be colour coded, although those pictured appear not to be. Poor work.
But anyway, there’s a simple answer to that, you just get a tester screwdriver, cost about 5 francs, and touch the end to each of the two screws in turn. One of them will cause it to glow, so that’s the live side to connect with your ‘L’.
Yes its the house wiring. Prettty confusing but your suggestion about using a test screwdriver worked. Thanks
There’s more to that story, if it’s true. than you recall here. For a start the gas and water piping would be entirely separate from each other; secondly they will both be earthed, so if they were somehow connected to Live then the circuit breaker would trip; thirdly, the cooker can’t somehow magically reverse the live and neutral - the worst it coud do, assuming there was an earth which was connected to the Neutral (which is tha case in pars of my house) , would be to connect live to earth, instantly tripping the circuit breakers.
So to somehow electrify the shower would take a lot more dodgy wiring, illegally so, than simply connecting a plug the wrong way round.
It sounds like a grounding issue, very common in France in the 1970’s getting a shock in the bath if you touch the taps.
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Never had that, but I did have another dodgy earthing issue at our house (1980s built) in Alsace.
An old fridge had managed to short itself out - not much of an issue in itself but it tripped not just the circuit it was on but the entire main switch. Easily resolved by unplugging it, but it was built-in and a pain to access, so it was a few days before I was able to access it. Anyway, turned out that several circuits running on different phases all came back to a common earth rail on the house side of the supply, so trip one circuit, trip them all,
Anyway, was all resolved by a local electrician, but it makes me wonder how it had ever been allowed like that in the first place and what else might have come of if in different circumstances.
Without this answer I would have connected the wrong cables and once again would have blown out all the power in our apartment block. 
No, you really would not. You would never have noticed, and unless there was something inherently wrong with the building wiring there would be zero risk of damaging anything.
Assuming someone did the proper job and the light switch disconnects the live wire, then you may easily detect which wire it is with the so called neon mains test screwdriver / Phasenprüfer when the light switch is on, and then check if the live wire is really disconnected with the switch off. And always switch off the circuit breakers before actually working on it.
Never touch a wire before testing it with the tester and never grip it before touching it with the back of your palm. Especially if you work alone. Circuit breakers down (all of them, no room for a mistake), light switch off, mains tester, last test with the back of your hand and only then work on it. And there are insulating gloves for working in iffy conditions (e.g. it is a large building, someone else might put the circuit breakers back on unaware of an ongoing repair etc).
I am not an electrician but I made my mistakes and believe me the subjective eternity between gripping a live wire and the RCD tripping is not a nice lesson 
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This, but I found the instructions are a bit confusing. You do need the circuit breakers on to test for the live wire. A test is then great to check that the correct circuit breaker is turned off - sometimes you need power somewhere for light or a tool.