R39 bulbs keep blowing

Hi All
We have a display cabinet lit by 3 R39 25 Watt E14 bulbs. These are screwed in to the top from inside and face vertically downwards.
I bought a 10 General Electric ones but they blow at an alarming rate. Anyone got any suggestions?
TIA for any advice.
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On Sat, 28 Mar 2009 19:07:20 +0000, Invisible Man wrote:

Overheating is the likely cause, can the air heated by the bulbs escape?
Another common cause is vibration, when on. Do you access the cabinet a reasonable amount with the bulbs on? Does it move or shake as you move about the room?
Is your mains voltage on the high side?
Any or a combination of all these could contribute to short bulb life but I susepct the first is the major contributor.
--
Cheers
Dave.




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Dave Liquorice wrote:

Thanks Dave. Like you thought heat might not be helping. Hence my reference to the position of the bulbs. Expensive cabinet so don't want to do too much to it. Vibration not a problem. Mains voltage never shown as excessive on my meter. We do have overground cables to the house but does not appear to be storm related.
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On Sat, 28 Mar 2009 21:25:26 +0000, Invisible Man wrote:

That's probably not a problem. I very much doubt that there is more than a few hundred yards underground on our supply from the the 125kV grid. That will be about 25 miles at 33kV, about 3 at at 11kV with the last 15 yds at 240v.
--
Cheers
Dave.




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Invisible Man wrote:

Put them on a dimmer and don't run the dimmer at full?
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Invisible Man wrote:

Really those sound like a crappy choice of lamp for the job. 25w mains lamps have fragile filaments & low energy efficiency, and theyre in a cabinet with doors.
low voltage halogens are pretty bomb proof, you might be able to change the holders and add a transformer.
NT
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230 volt 15 watt compact fluorescent spotlights are available, and seem to be robust and stand a wide variation of voltage, and put out more light and use less power and generate less heat.
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