The 12v one, BECAUSE in your test the gu10 blew first so it is no longer working, which means the 12v one is still on so it draws more current by default since it is still working.
and you are going to say the real answer is the they both draw the same, to which i would ahve to say you are wrong, because you clearly said
Actually it's not a 'trick' question, but a question customers are always asking. And an answer electricians often give is that ELV is more efficient. Obviously the power is the same. (But DESL is right as he is using VA rather than W.) A 50W ELV uses (approx) 4A at 12v, so what is the current on the LV side?
Academic as the comparison is what is the power drawn on the 230v side. Per the above there's very little difference. Small losses in the transformer (no big copper or iron stuff in those these days)!
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