kitchen lighting

I've just installed two of these:

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replace the 4ft florescents that wouldn't have looked out of place in an office.

Reply to
Peter Johnson
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I am sure you can once its splashed all over a kitchen!

(I recall a school friend of mine who had a party trick involving a candle, and a bicycle pump full of paraffin - it made quite an impressive impromptu flame thrower!)

Indeed. The house I grew up in had a 4 or 5' tube in the kitchen and it never seemed unusual. In fact I have one here in our utility room. Aside from the need to sweep the dead bugs out of the diffuse from time to time it does the job and does not look too bad.

Hmmm, yes I got some grumbling on that one. One trick I found is to cut out a hole the size of the base of the lamp and set it into the ceiling so that only its diffuser sticks out. However it was accepted that with no street lights, practicality had to trump aesthetics on this one. So we have one at the top of the stairs, one in the hall, and another beside the fuse box.

I can see the logic for conduit systems and round BESA box mounted accessories. So perhaps the plan is that you can carry on using the same fittings in more "flush mounting amenable" locations?

Reply to
John Rumm

Phosphors for tubes are made in Europe, whereas phosphors for CFLs are made in China. However, they are the same product.

There is expected to be a shortage of phosphors for tubes over the next few years, as there aren't enough rare earths being mined and China will need most of what it mines for it's own use, leaving not enough to export for tubes. New mines will come online a couple of years after that, so it's not a long-term problem, just short term.

They use different proportions of the tri-phosphor mixture. CFLs are designed mainly for home use where they have to blend in with filament lamps, and home lighting levels are much lower than those in offices, which is why a lower colour temperature looks more correct in the home than in the office.

Reply to
Andrew Gabriel

Like the look of the fitting but the output is a bit low for my needs. A couple of years ago I put up a Thorn Diffundi surface fitting with

2x58w 5ft triphosphor tubes to supplement the MR16 units over the work surfaces and have been looking for something less functional ever since.

-- rbel

Reply to
rbel

levels of electric lighting, things look much higher CCT to the eye.

countries people often prefer warm low CCT tubes, in hot coutries they mainly use cool high CCT tubes.

Thanks. That's interesting, I would not have thought of that before, but it makes sense now that you have said it.

I think I will buy a 2700k tube to try, now that I am used to 2700k light from my CFLs.

From a quick search on the internet, 3000k seem more common than 2700k tubes. Is there a noticeable difference between 2700k and 3000k? I assume there is, otherwise there would be no point making two different types. I will probably buy a 3000k tube as well, to see which I prefer. What else has a colour temperature of 3000k? Would I have a 3000k light at home already that I could use to compare?

TIA

Reply to
Fred

levels of electric lighting, things look much higher CCT to the eye.

countries people often prefer warm low CCT tubes, in hot coutries they mainly use cool high CCT tubes.

Halogen lighting is about 3000k

NT

Reply to
meow2222

levels of electric lighting, things look much higher CCT to the eye.

countries people often prefer warm low CCT tubes, in hot coutries they mainly use cool high CCT tubes.

The theory comes from a Dutchman, Kruithof. Look up Kruithof Curve. There is a Wikipedia entry, but it often gets damaged by people editing it who don't actually understand it as much as they think they do.

6500K will look perfectly natural if you achieve midday sunshine lighting levels, which would require covering most of the ceiling with fourescent tubes. Artificial lighting levels in the home tend to be nearer to outside lighting levels at sunrise/sunset, when the sun has lots of the blue filtered out (some is reflected from as the "blue" sky, but not as much as is lost).

There are a number of companies using tri-colour LEDs for dimmable lighting, which also change the colour temperature with the dimming. Filament lamps do this naturally anyway.

There is if you can see both together. Otherwise the likely increased lighting level generated by tubes will make 3000K look right. In a kitchen which is genuinely used for food prep, choosing a higher lighting level which makes 3500K look right is a good thing anyway. Using 3500K or higher at too low a lighting level will make things like meat preparation more difficult.

The very slightly blue tinted (but still legal) car halogen headlamps (the blue only visible where concentrated in the pinch seal).

Reply to
Andrew Gabriel

levels of electric lighting, things look much higher CCT to the eye.

countries people often prefer warm low CCT tubes, in hot coutries they mainly use cool high CCT tubes.

IME Mains halogen is probably closer to ordinary filament lamps (i.e.

2700K). LV halogen is a bit higher.

The LV LED MR16 spot I just fitted adjacent to some LV halogens claims

3000K is very slightly "whiter" than the halogens, but there is not much in it (in fact, compared to new bulbs they would be pretty close).
Reply to
John Rumm

Thanks.

Reply to
Fred

Thank you. That has taught me a lot.

I think I finally understand that it is not just about the colour temperature but also its brightness too. A high colour temperature needs a high brightness to look right, otherwise they look too blue.

It is not that 3500K is the right colour for kitchens, it's that 3500K lighting should be brighter than 2700K or 3000K, so it's the increased brightness that helps with food preparation rather that the colour.

Have I got that right? Or is my understanding flawed?

I don't do much meat preparation. I buy it and put it in the oven and that's it! How does a dim 3500K light interfere with that? Is it that the light is too blue, stopping you seeing how red the meat is, so that you can not tell whether it is too rare? Is it a similar theory to blue lights in public toilets to stop drug addicts?

Thanks again.

Reply to
Fred

I wonder why that is? Perhaps they make the mains ones match filament lamps so that they blend in around the home?

Reply to
Fred

No. Its a simple mechanical fact. The LV halogens have MUCH thicker filaments and can be run hotter as a result.

Reply to
The Natural Philosopher

Interior lighting is chosen firstly for its light level, then you can, with= some lighting technologies, select what CCT you want, which is to an exten= t a matter of taste and colour rendition accuracy. You also get to choose C= RI, which is again very much about colour rendition and appearance.

There's no right or wrong about 2700K or 3500K in kitchens. 2700 makes thin= gs look a bit yellower, and blues dull, 4000K makes them look a bit lacking= in red content and a bit over the top on blue. 3000 is a good choice, but = fl tubes in 3000K are often not of good CRI, 3500s are much better. There i= s more to the story of course.

You'll be able to see fine under 3500, but it will look different under 270=

  1. They eye partially compensates, so try them side by side to see.

NT

Reply to
meow2222

You can take 20% power consumption of fl tubes using a capacitor with very little efect on life expectancy

NT

Reply to
meow2222

Wot a "Wattless dropper"?..

Reply to
tony sayer

LV halogens are more efficient - giving more lumens per watt. The higher temperature comes with the higher light output.

Reply to
John Rumm

Seems ok so far.

There is a further wrinkle in that some light sources have better colour rendering than others. This is not directly to do with colour temperature as such, but to do with the spectra emitted.

Filament lights have continuous spectra like daylight (although a bit weak at the blue end in most cases).

Discharge / fluorescent lights, usually have big gaps in their spectral output, plus some strong spikes at other frequencies. The result can be a light that is as bright, and appears the same colour temperature, but does not render colours in the same way and still looks a bit unnatural.

I think that is based on the idea its harder to see the blue tracks of a blood vessel when the skin is rendered blue as well.

Reply to
John Rumm

For iron ballast fittings a wattless capacitor dropper's good. for electronic ballasts I'd probably put the cap between ballast and tube.

NT

Reply to
meow2222

I don't believe this is true.

Halogens can be run at higher temperature, but that's not done in domestic lighting. The reason is that halogens cost much more to manufacture, and people won't pay for higher efficiency (those few people who will aren't using halogens in the first place). So the only way they can be sold for a higher price is on longer life. That's done by running them at 2700, same as regular filament lamps, which gets you about twice the life.

OTOH, car halogen headlamps which are all rated much less than domestic halogen lamps, do run at higher temperature. However, people expect to pay more for those, and they expect them to be higher colour temperature, so much so that they're often lightly tinted blue, which actually makes them dimmer and less efficient ;-).

The lower efficiency of mains lamps is not due to running at lower temperature. If you work out the length and crosssectional area required for a 100W mains filament lamp, and simply make a long enough wire, it won't glow white hot because the surface area is much too large and it will dissipate 100W whilst only glowing a dull red, if you're lucky. The way this is resolved is to reduce the effective surface area by coiling the filament - to a first approximation, from the point of view of emmissivity and surface area, it now behaves more like a shorter fatter wire, with much less surface area, i.e. more like a LV filament. This process isn't perfect though - a lot of the light from the internal parts of the coil is lost by the time it's reflected a few times and escapes from the filament.

For any given power output of a filament lamp, there is a most efficient design voltage, taking into account all the factors, and for a 100W lamp, it's around 55V. As you increase the power, the ideal design voltage increases. I don't know at what power rating the ideal voltage reaches 240V, but I suspect it's probably well over a kW.

Reply to
Andrew Gabriel

ballasts I'd probably put the cap between ballast and tube.

Kills tubes quickly (due to high crest factor), which is why it isn't used. Thorn developed what they called lag/lead fittings, where half the tubes use inductors, and the other half use capacitors, and together the power factor is not far off 1. However, the "lead" (capacitor ballasted) tubes still have to have a (smaller) series inductor, to reduce the crest factor so you get reasonable tube life. The crest factor with inductive ballasts at mains frequency is very bad.

All current electronic ballasts in the EU are effectively wattless. They all achieve full light output whilst the total circuit watts are less than the tube rating. They are able to do this because the tubes operate more efficiently at high frequency (and it's a requirement in the EU that they do this).

Reply to
Andrew Gabriel

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