I'm fed up with the 20w capsule bulbs I'm currently using, because they seem to fail on an all too regular basis ( and are a b****r to fit anyway ). LED lights don't come cheap, by the time you've scattered them all around, so I've been looking at the T4 fluorescent tubes. They come in a broad range of ratings from
6W through to 30W and although one site I looked at gave rough equivalents, but how accurate they are I'm not sure.
So the question is, what is the best rating for a virtually continuous run of lights, mounted 450mm above a light worksurface ?
The tubes have a pretty constant power per unit length, so it doesn't make much difference which you use for a continuous run. Longer ones will be more convenient to fit because you'll need fewer of them, but avoid too many different lengths or you'll need many different spare tube sizes.
Note that T4 tubes are not standardised -- make sure you buy ones from a supplier which is going to be around for a while (expected life of the installation), and carries spare tubes. Might even want to get spares up-front. Fortunately, I did this with my Omicron ones, which went out of production a few years back now, although I'll probably run out of one tube length this year.
T5 tube lengths are standardised. I've posted a few articles about using those in this circumstance.
Suitable power is to some extent a matter of opinion, what people like tends to span somewhere vaguely in the region of 3:1 powerwise. The other issue is that once you've chosen (blind), you can't then change the tubes' output.
There is a solution: dimmed fluorescent lighting. This is easier to implement using full size T8 tubes, eg 2', 4', and a) you can set the light level to whatever you want whenever you want b) a quarter as many tubes means as quarter as many tube failures b) and a quarter as many replacement tubes bought d) you need far less fittings, ballasts and dimming kit. e) fatter tube means less glare if you ever see it directly from some angle f) you can get replacement tubes just about anywhere g) you have a wide range of tube CCT to choose from, and can change CCT any time you like h) you can get good CRI tubes i) you're not tied to any supplier j) tube lengths & powers are standardised across all suppliers k) you can have pleasant low level lighting at night l) its very simple to get the dimmer to ramp up light level over a second or 2 at switch on if you like that sort of thing
About the only downside is you've got to make cutouts under the cabinets to enable the tube to run full length, but that's fairly trivial.
BTW the tube is best held in clips with it more or less touching the wood above, and the ballast housed separately. There is of course no space for a full size fitting.
I used T8 tubes for this mounted in terry clips with separate ballasts. They are hidden quite nicely behind the plinth underneath the wall cupboards. Used these dimmable electronic ballasts:-
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they use just a plain pot to dim them so will need a circuit added to for that - just two wires at low voltage.
Expensive - but not much more so than those linked types and a much better solution.
Thanks NT and Dave for both those suggestions. I like the dimmable option as it can be set up then to suit anyone. Another objection to the LEDs was that they may be too harsh !
My local Homebase uses LED bulbs in its lighting displays, even though the fittings concerned usually come with halogen bulbs. They have three different colour temperatures.
One is very blue, and they sell these LED bulbs. The other two are white; there is a brilliant white which is quite impressive compared with LEDs of the last couple of years, and a slightly yellow white which looks like an attempt to replicate daylight (with obvious limitations). These two are not told in the shop and the staff couldn't tell me where they came from.
I wish they sold them; I would buy a couple of each to try them and, of satisfactory, change all my GU10 halogens to LED.
I'm building some lights using LEDs at the moment -- this is my first serious attempt to use them for lighting. There are warm white ones, but they're still a little too cold at >3000K, and they're only half the efficiency of the ghastly cold white ones, which means acceptable colour ones don't win any efficiency wars. In my case, the tiny light source lends itself to much more accurate beam control than is possible with fluorescents, and instant full brightness at low temperature is also a win, and the lighting requirements are low. These are one of the few combinations of requirements where LEDs currently have a possibility to shine through;-).
I'll put together a web page describing them if it works.
I'm wondering if you're looking at a minature metal halide lamp? These are in very widespread use in retail display lighting. They are generally available in warm white, white, and daylight.
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