wrote:

Can anybody tell me of the relative advantages/disadvantages of going
low voltage or mains voltage for this lighting?

What the others said, plus:

12V will give a better colour spectrum than mains halogen - so a more
natural "daylight" like light.

12V is available with dichroic reflectors which will aid point 1 above,
and will also result is less heat being projected forward by the light.
(correspondingly, more heat being lost though the back of the bulb into
the fitting and surrunding area)

Modern 12V transformers tend to be Switched Mode Power Supplies rather
than actual transformers. Hence they are smaller, lighter, and more
efficent. However they do produce more EMI that can be picked up in
succeptable equipment like analogue cordless phones etc.

--
Cheers,

John.

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