I didn't read Ragnar's post carefully enough (I read it as !"Class 2", not "Class 3" as written). I would expect the lights to be Class II, not Class III (hence with no 'earth'(or LV) within them), wouldn't you?
Domestic rental, 18 downlighters stopped working
- Thread starter SUNRAY
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These certainly had 230V between the live wiring and the metal frame so I assumed they had an earth terminal or 2. They looked like they had about 6 spring terminals. I didn't want to risk damaging the little plastic lugs of the JB enclosure by opening it so couldn't see what markings they had
Fair enough.
I suppose that, if (as has been suggested) they were Class III that would require them to have an SELV supply, which I suppose would preclude there being fed with 'a small bit of the supply voltage' from an earth-referenced (LV) supply (which is what you were looking at) - but I do not think it would preclude metal parts of the equipment being earthed (provided that the supply itself was not 'earth referenced').
I would expect 12V downlights to be deisgned as class 3, and their misuse by wiring in series on 230V to result in them being class 0 or worse.
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Fair enough, although I think that"Class 0 or worse" is probably a bit OTT.
However, as I've said, in practice I don't think that there is actually any credible insulation which would not be capable of "withstanding 230V),so I'm not sure that (rules and regulations aside) there is actually much of a problem, is there?
I am reminded of this: https://www.bigclive.com/halogen.htm
That's really very different from what we've been discussing ...
In that DIY chandelier, there is no 'insulation' at all. 'Instead, 'bare' connections to a pile of lamps in series (which will be at potentials varying from )v to 230V relative to earth) are exposed and 'touchable' (or would be if they weren't too high up to touch).
That web page has been around for several years. I was unable to quite fathom out, how the neon operates - 'The little neon lamp and resistor is in parallel with the whole PCB's load so that it lights if one of the lamps on that level goes open circuit.'
Serveral is probably an understatment....thinking back, I can remember stumbling on it about the time I was doing my A levels ... so and that (and I'm still struggling a little to beleive it myself) was about 20 years ago! :O
When all the lamps are good the voltage across each of the 5 levels should approximatly 48v which is below the neon's stricking voltage, when a lamp goes open cirucit, the full mains voltage will appear across that level and allow the neon to strike, the current of the neon will be too small to result in a significant voltage drop across the other lamp fliaments, perhaps a handfull of volts at max so it'll still be sufficient to keep the neon lit
When all the lamps are good the voltage across each of the 5 levels should approximatly 48v which is below the neon's stricking voltage, when a lamp goes open cirucit, the full mains voltage will appear across that level and allow the neon to strike, the current of the neon will be too small to result in a significant voltage drop across the other lamp fliaments, perhaps a handfull of volts at max so it'll still be sufficient to keep the neon lit
Thanks, got it now..
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