On 10/11/2012 07:18 PM, Dave Plowman (News) wrote:
In ,
Jeff wrote:
The lobby and foyer lights were mounted on the ceiling, pointing down.
One would think that there would be plenty of hot air accumulating
near the ceiling, but that wasn't the case. That's where the fan
ducts were located which helped to cool the lights. Few of those
lights ever burned out.

The marquee lamps were mounted on a vertical structure, with the lamps
pointed horizontally.

Vertical mounting for a GLS lamp seems to give a better life than other
orientations. A rough service type may have had a better life in this
application.


The filament temperature goes up more slowly than the ambient, since
it's radiatively cooled, but a rise of, say, 50 degrees would probably
have a significant effect on bulb life.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net