Blue Bulbs on S Stock

The yellow-looking tubes are a "warm white" colour (temperature 3000K, denoted as 830 on the tubes) and the closely related 2700K is what you'll find with most CFL energy saving bulbs used everywhere. This colour of tubes has also been used in the various Siemens Desiro classes. At the opposite end is "daylight white" with a colour temperature of 6500K (shown as 865 on the tubes), which gives a very harsh blue tinge if you are not used to it but is actually close to that of bright sunlight.

However, the replacement tubes I have seen are in the middle of this range, at 4000K (shown as 840) or "cool white". This is the colour used in the A, C and D stocks, although replacements in the C stock in recent times were of the warmer colour. They will look a bit blue next to the yellow of warm white. The easiest way to work out which is used is to look at what is written on the tube itself!


Cool-White and Warm-White T5 fluorescent tubes by hassaanhc, on Flickr

I think I may have mentioned it before on this site, but I remember several years ago I started noticing one or more D-Stock carriages with unusual lighting. It was clearly a 'daylight' type of tube but had the odd effect of making the inside of the carriage seem brighter than daylight itself, even on a sunny day, if the train was in the shade.

Obviously it's not at all unusual to see a train brighter that its environment, but doing so when you were not underground and could see blue sky and sun in a different part of your field of vision was odd, As I remember, the D stock did get cooler, brighter lighting, but not to the same extent as what must have been a couple of test vehicles.

If they are LED tubes they may just be faulty.

Power surges can affect them.

I doubt it LED's are low voltage devices and are more robust than the filament bulbs they replaced! "White" LED's tend to have a blue tinge to them as well

The white is made up of 3 colours and when one colour fails the tone of white changes and a blueness is one example of this.

I must say I totally despair at how in the last couple of years the simple subject of train lighting has become such a 'fad' that virtually every type of train now seems to have a different type or colour of lighting, including some wholly ghastly and vile designs which appear blue or "daylight".

Last year I rode on 205032 on the Dartmoor Railway, which still retains what appear to be the same flourescant tubes as on the day it was withdrawn, so nice just to have a train with 'normal' lighting, not too bright, and no silly colours. Felt like I was 10 years younger again.

For what it's worth, my home remains very nearly 100% tungsten, and will be for many years to come! :-)

Agreed 100%. I'm not sure if some of the LED street lighting is deliberately dimmer than what it replaced, however I find it doesn't light up the road nearly as well. My car retains conventional headlights, and I'm very glad it does.

As an aside I also find some of the fittings highly unattractive in appearance, but obviously this is my personal view.

'fraid not.

If green failed, you would get magenta, not blue tinged white.

If red failed you would et cyan, not blue tinged white.

If you were generating white light by having a large number of R, G, and B lamps, failure of a number of lamps, even if all the same colour, would result in a blotchy appearance, not a blue tinged white.

Mmm, I can see how that could happen, as humans are very bad at identifying colours (actually it's because we are uncannily good at adjusting for the changing colour of sunlight [which also spills over into adjusting for all sorts of tints of artificial light], according to the time of day/year, vital to quickly detect danger and food), so a cyan cast might appear blue, particularly if the green component is quite blue to start with - something I have noticed in quite a few LED's.

You'd be talking there about the phenomenon of colour constancy and the retinex theory of Edwin Land (of Polaroid). I spent a great many years working in that field!

Don't worry. We'll run out of indium before long.