DIY Doctor

Swapping Light Bulb Type And Comparing Tungsten, CFL and LED Bulbs

Postby ericmark » Thu Oct 03, 2013 8:04 am

Started with 100W x 2 tungsten moved to 60W x 6 tungsten then 11W x 6 CFL then to 8W x 10 CFL with an output of 310 lm. These were Philips SES (E14) with a life of 10 years before 50% should have failed but they did not last anywhere near that time and the cheaper 8W replacements were slightly larger in globe size and brighter the other room also had 6 of the same size lamp so all 6 replaced with larger type and spares kept for main room. 3 years on and only 6 of the original 16 left so much for 10 years to 50% failure.

When two had blown I had two 1.4W 100 lm LED candle bulbs bought for reading lamp so stuck them in until I could buy new. Rather surprised as seemed same output at original 8W 310 lm bulbs. Two more failed again temporary replaced with 5W folded tube CFL and again brighter than original. Lidi then had some 3W 250 lm LED candle bulbs bought all they had and replaced all the non candle bulbs with 8 of these so now all matching even if two are slightly dimmer being 1.4W 100 lm and oh what a difference.

The room has never been so bright. 2200 lm of light is it would seem more than 3100 lm of light!!!

OK satisfied with the room instant bright light but with the rated lm output and watts used clearly not anything to do with how good the bulbs light the room how do we select lamps?

I do wonder how much is to do with the direction the light leaves the bulbs I note LED lamps are often given an angle of spread so although they seem to radiate light in all directions they may send most of it up to the ceiling which being white will reflect well. However sure the CFL were really the same.

So if watt and lumen input and output don't give us how Tungsten, CFL and LED compare how do we select replacement bulbs?
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Postby proptech » Thu Oct 03, 2013 10:27 pm

Hi ericmark
Good you've solved it in your room, but what a subject !
It seems to be a complete mess, who could possibly make the choice, at least when all we had were tungsten, there was only the various makes to chose from. 100W was 100W end of story !
Now it seems the manufacturers are not helping, packaging is misleading, and there must be a large tolerance on output. Perhaps they're trying to make the things too cheaply.
The other thing that comes to mind is deterioration of output with age, how many times do we change a bulb and think 'that's brighter than the old one'
I suppose that soon LED will be universal, and there will be no choice - a good thing maybe ?

So my opinion on your question of how to chose is - no chance, it's just pot luck !
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Postby ericmark » Fri Oct 04, 2013 1:42 pm

To my mind energy has to go some where and if it goes into making light then the bulb will be cold but if waisted the bulb will be hot. However that does not account for light either side of our visual spectrum.

The heat from the CFL makes me think they are not that efficient at making visible light and having to use coatings to convert from UV to visible can't help.

I tried to measure holding a white sheet set distance from lamp and use cameras light meter should have worked but when I tried to measure watts used I found my watt meter does not like the low wattage and with a 5W CFL bulb it flicked between 2 and 4W so OK to measure 2kW but not 2W.

However I swapped to CFL not to save energy but to save maintenance with 6 bulbs it was one every other week and in 2 years it has been one every other month so yes improved. However reading spec on bulbs it should have been one a year so only lasting 1/6th of the time they should have done.
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