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It's Not Magic, It's Work!

01 Jan 2011

Light Bulbs

Yesterday we were at our local DIY store looking for light bulbs and loft-insulation. There is a bewildering list of stuff available even in a small B&Q. Annoyingly not what we wanted. We did however get some things.

Light bulbs in the UK are annoying and getting worse:

  • Most sensible fittings use a bayonet fitting such as the BA22d/BC. In the past few years there has been an influx of cheap tat from China using the alternative Edison Screw fit system. That now means you have to deal with two incompatible socket and bulb systems.
  • There are also three kinds of bulbs in use, plain old "incandescent", "halogen" incandescent and compact fluorescent ("cfl"). Most bulbs quote their energy use in Watts and not their light output in Lumen.
    • So the newer bulbs will say something like 11 W, output 75 W. Meaning 11 W in electricity and the light out put of an old style incandescent 75 W light bulb.
    • To add to the complexity, most of the new and very popular halogen bulbs use a wide range of strange fittings and are a royal pain to find. Additionally they don't quote their light output or an equivalent to incandescent!
  • LED bulbs are also available, but they are very expensive and limited in output so hardly used yet.

At long last some things are starting to change. Old inefficient incandescent bulbs are being voluntarily phased out of use. To try and avoid confusion between the remaining bulbs, they are now at long last putting the luminosity of the bulb on the boxes, so you can at last compare them and have a better understanding of what is going on!

Lamp Type Typical Wattage Lumen Per Watt Typical Lumen Expected life (days) Cost per bulb
Incandescent 60 12-15 720-900 41.7 £30.00
Halogen 50 15-25 750-1250 125 £25.00
Compact fluorescent 11 60-80 660-880 333.3 £5.50
Fluorescent Tube (strip light) 10 80-100 800-1000 416.7 £5.00
LED 5 100-125 500-625 5 years £1.50
Life time is total running time, assuming normal usage patterns.
Cost is total running cost in electricity and bulbs over 5 years.

Modern cfl bulbs are much quicker to start then older ones, but still not as instant as incandescent (old or halogen). Some of them do claim to reach a high output level very quickly and there are clear differences between bulbs.

Modern cfl bulbs are available in a variety of colours and though I do have some in the house that are slower to start none of them have funny colours that they were prone to a decade or so ago. I've not seen oddly coloured cfl bulbs in over a decade.

Modern cfl bulbs do not flicker, cheap magnetic ballasts can cause flicker but almost all modern fluorescent lamps use electronic ballasts now - which also means they reach peak light output very quickly too.

Modern cfl bulbs are now available in a wide variety of shapes, you are not stuck with the old folded "U" shaped tube design. However the straight "U" shaped design is the cheapest and most efficient.

You can even use some cfl bulbs in dimmer systems, though they do not have the same range of light output as old incandescent bulbs and they are very expensive.

Finally if you really, really don't want use use cfl (like my father) you can now get halogen incandescent bulbs that are designed as alternatives to plain incandescent bulbs and while not as efficient as cfl or LED they still give our more light and less heat than plain incandescent bulbs.

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