wrote in message
...
Steve wrote:

"simon beer" wrote in message
...

Also what are the advantages or disadvantages in fitting mains powered
as
opposed to low voltage ones. These are to be fitted in the kitchen.

We have both types in our new kitchen. I wish I'd gone for low-voltage
ones
all round, as they have a much nicer light quality - sort of whiter,
more
twinkly and modern looking. The mains voltage ones have a yellowish
light,
rather like a tungsten bulb.

Er, they *are* tungsten bulbs! :-)

--
Chris Green )

The reason for the 12v lamps being whiter is that they run at a higher
temperature. Because they carry a high current at low voltage, the filament
resistance is very low - so the filament is very short and fat compared with
a long and thin one in mains lamps. This, in turn, means that it is
physically much stronger and can run much hotter without failing. As any
schoolboy will tell you, the wavelength of light emitted is inversely
proportional to the temperature. Thus a higher temperature means that much
more of the radiation emitted is in the visible part of the spectrum rather
than down in the infra-red. This means more visible light (and less heat)
per watt of input power *and* the light emitted is whiter.

Roger