On Mon, 14 Jan 2019 10:31:56 +0100,
(D.M. Procida) wrote:

I assume it would not come to any harm run at a lower voltage, though I
know that some lamps can darken as the result of deposits on the inside
of the glass when run dimmed.

The darkening is metal vaporizing from the filament and settled on the glass.
The bulbs that habe a mechanisnm to avoid this are the halogen bulbs: the glass
is run hot, a halogen scrubs the metal off the glass, and re-deposits it on the
filament.

This is positively not a halogen bulb -- run it with as low a voltage as you
like.

The lifetime of a lightbulb is exquisitely sensitive to to voltage, something
like (voltage/ratedvoltage)^-12 to (voltage/ratedvoltage)^-14. So running a bulb
at 99% of the rated voltage will increase its life by 12-15%.


Thomas Prufer