So, before we get into this, let me have a quick side rant
+++side rant start+++
So, I'm an EE student, as many here probably are, and at the moment, I highly doubt the german universit system.
Today, I tried to change the kitchen light in my flat.
That's when I noticed, that by now I am able to do fourier transformations and taylor polynoms without a calculator, I can work with matrices, vectors and tensors and all that good stuff, though I learned to use matlab and maple i detail, which we're not allowed to use although we could (duh).
To this point, no-one has shown us how to use a scope or even a meter, we don't know how whatever electronics, say opamp or 555 work, and I am, three years in, seemingly still unable to hook a bloody lamp to my kitchen ceiling.
So, what am I doing wrong? Was I expecting the wrong things? Did I inscribe to the wrong university? Am I studying the right thing? And does it get better?
+++rant end+++
To my problem.
In my flat, there were these old lamps, sixties-gramdma-style, big ol' 40W bulbs, that weren't mega bright too, so I decided to take them off and go for some new ones, GU10, so 230V as well.
First of all, weirdly enough, the old lamp was connected unearthed, although it clearly provided an earth terminal. The connected wires were, to add to my surprise, brown and green/yellow.
(In case you didn't know, in central europe, usually brown is line, blue is neutral and yellow/green is earth)
So, measuring with a multimeter, I really had 230V from brown to yellow, so smells already of drunk uncle Bob wiring, but the floating blue wire measured 30odd V to the brown and 80odd V to the yellow wire. No clue where that's from.
So, I connected the line and neutral of the lamp across 230V and connected the blue odd voltage wire to the earth terminal on the lamp.
What happens now, is that the lamp works fine, when I turn it on to test it, then I go on and close the encasing and adjust the spots, still works fine, mind my business and suddenly 20 minutes later the lamps turn off.
So, flip the breaker, up the ladder open the lamp, everything's fine, turn it on, works, close it, and 20 minutes later, darkness.
Did the whole routine about five times.
I do not have many clues to what that is, but I have a few hints on what it ain't:
-Does not trip the RCD, not that I ever met one in this house, but if there is one in the basement I've never seen, doesn't trip that.
-Does also not trip the breaker, so no short there
-I can't measure the voltage because the error only occurs if the thing is closed
-Maybe has it to do with the misterious blue wire, is it worth a try to disconnect it? (Don't wanna be electrocuted, and for all it seems, this is the earth)
-Could be thermal, as those halogens can become quite hot
-When I leave it dangling on the wire clamp, it works perfectly fine.
-Could be that the lamp is shaffordable, students are always on a budget, it's one of those hardware store lamps, didn't cost an arm and a dick
-Occam's razor suggests it's a wonky connection, but the wire clamp seems tight to me
-Finally Murphy's law suggests a fault in the house's wiring, which meant ripping off the whole ceiling plates and rewiring the house
If anyone could either support one of those possibilities or exclude one, or maybe think of another solution to the problem, that I haven't thought of, I would be really grateful for support.
I have a second exact same lamp, I will, just to have tried, swap them out as soon as I got daylight.