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Topic Title: Low energy light bulbs fail quickly in outdoor light units
Topic Summary: Low energybulbs fail quickly when used in outdoor lighting fittings - why?
Created On: 03 June 2012 12:49 PM
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 03 June 2012 12:49 PM
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Joined: 03 June 2012

I have noticed that low energy light bulbs fail very quickly - within days or very few weeks - when used in outdoor light fittings. Is there a reason for this rapid failure and can it be avoided?
I have a bulkhead type dusk-to-dawn security light fitted to my garage external wall which uses a photosensor to switch the light on at dusk and off at dawn. It was supplied with a 60W incandescent bulb.
When I replace the incandescent bulb with a low energy bulb (small - say 8W), the low energy bulb invariably fails after a few days, or weeks at the most. One low energy bulb lasted a number of years (I wish I could remember what brand!).
Also, when I replaced an incandescdent bulb in one of those "glass envelope under a swan neck support bracket" outdoor fittings, it too failed within days.
I can see no good reason to this rapid failure mode. When mentioned to friends they too see the same problem. As incandescent bulbs are to be phased out in 2012, a solution would be useful - preferably not requiring LED bulbs at almost £20 each.
 04 June 2012 12:51 PM
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The switching device needs to be suitable to support energy-saving lamps.

I've got three around my property using IP65 Steinel Dusk-Dawn PIRs (so switch more frequently). These devices are suitable for CFLs, which I've got in standard IP66 platic bulkheads (metal light fittings outside no good near us as we're on the coast), and in 2 years, have only had to replace the CFL in the bulkhead over the garage side door, probably because this door slams shut and the mechanical vibration damages the lamp. Of course, the lamps have been operating well outside their temperature range, as we've had a few -10 degree C nights too.

EUR ING Graham Kenyon CEng MIET TechIOSH
Principal and Proprietor,
G Kenyon Technology

 04 June 2012 02:12 PM
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Thank you. Your response prompted me to google CFL and I came across this wiki article which suggests that overheating in the enclosure may be the cause as it shortens the ballast's life.
See which says "Some CFLs are labeled not to be run base up, since heat will shorten the ballast's life. Such CFLs are unsuitable for use in pendant lamps and especially unsuitable for recessed light fixtures. CFLs for use in such fixtures are available. Current recommendations for fully enclosed, unventilated light fixtures (such as those recessed into insulated ceilings), are either to use 'reflector CFLs' (R-CFL), cold-cathode CFLs, or to replace such fixtures with those designed for CFLs. A CFL will thrive in areas that have good airflow, such as in a table lamp."
Reference 71 points to which is a most interesting discussion of the merits or otherwise of CFLs, and where some Philips bulbs are recommended for enclosed fittings and outdoor security lights. I then searched my "to go to recycling" box and the bulb which lasted was a Philips Genie 11W CFL with 3 U-tubes about 50-60mm long.
Googling IP65 Steinel Dusk-Dawn PIR brought up the Elektra 60W bulkhead fixture which says it is suitable for low energy bulbs, and where the picture on the packaging recommends a "long, straight" CFL, not a spiral one.

Edited: 04 June 2012 at 02:22 PM by JRHa

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