Don Klipstein wrote:
In . com, Arkadiy wrote:
Smitty Two wrote:

I put some halogens in my kitchen, whatever Home Depot had, and have
been happy with them. But, they throw a lot of heat up through the
cabinet floor, which isn't good for some foods in storage. Think about
insulating spacers of some sort if the xenons heat up, or keep dishes on
the bottom shelf.
Actually I knew there is a heat problem with halogens, which is cured
in xenons.

Hardly at all if light output is the same. The xenons will not be much
more efficient than halogens.

That's why I am leaneng toward xenons. What I don't
understand is advantages/drawbacks of line voltage versus low voltage.

In general, low voltage incandescents tend to be a little more efficient
than 120V ones of the same wattage and life expectancy. The shorter,
thicker filament can be operated at a higher temperature. A shorter
thicker filament also has less heat conduction to a surrounding fill gas
than a longer, thinner one. In fact, most 120V incandescents less than 25
watts and some longer filament 25 and 40 watt ones have a vacuum because
heat conduction from the filament by a gas hurts efficiency more than
efficiency is helped by the gas allowing a higher filament temperature.

It appears to me that typically 12V incandescents are mostly about 20%
more efficient than 120V ones of the same wattage and life expectancy.


Is there a wattage above which, in general, 120V would be optimum over
'low voltage'?

In the case of xenon fill undercabinet lights, all the lamps I saw were
12 or 24V. Do 120V lamps exist in this application or is 12/120V just a
question of where the power supply is located?


I started to write that someone should collect your posts to a FAQ -
then figured out you have a lot of information at:
http://members.misty.com/don/


--
bud--