/ Home & Energy

Why are you phased by the light bulb phase out?

Smashed energy-saving light bulb

When we wrote about the phase out of incandescent light bulbs recently, the response was overwhelming. So what got people’s backs up? I trawled through hundreds of comments to pick out the main complaints…

Your complaints ranged from cost to being left with less choice. Having tested energy-saving bulbs for the latest issue of Which? magazine, this topic is fresh in my mind, so I thought I’d try and tackle each of these issues one by one.

Unfortunately, I couldn’t address all the issues raised in our previous Conversation. Others included claims that energy-savings bulbs aren’t as bright, can’t be used with dimmer switches and don’t always fit light fittings.

1. Energy-saving bulbs don’t last as long as claimed

This can definitely be true if you have a bulb that’s poor for longevity, or doesn’t like being switched on and off frequently. The regulations only require 50% of a bulb’s sample to achieve the claimed lifetime – cold comfort if your bulb is in the half that didn’t.

Which? energy-saving light bulb tests show big differences between bulbs in terms of how long they last and how they cope with being switched on and off. We test three samples of each bulb and, at worst, all three fail long before our 30,000 on/off switching test is over. The best of the bulbs have all three samples working at the end of the test.

It’s the same with longevity – the top performers’ samples survive 5,000 hours continuously turned on – the equivalent of five years’ use. But poor performers will see some, or even all, samples fail before that.

2. Health side-effects including migraines, UV radiation and mercury

The most common type of energy-saving bulb, CFLs, do contain mercury, but only a small amount. An average CFL has no more than five milligrams – and would fit on the tip of a ballpoint pen. Breakages are easily dealt with if a bulb breaks, as detailed in our advice guide.

UV radiation is only potentially a problem if you sit very close (within a few centimetres) of a CFL-type bulb for prolonged periods. For migraine sufferers, using a different type of energy-saving bulb altogether (i.e. a halogen or an LED) or using a CFL with an outer surface as well as an inner (i.e. not a stick-shaped one), will also help.

3. Loss of heating from traditional incandescent bulbs

Incandescent bulbs did waste 85% of their energy as heat, but this is still a very small amount – the heating effect on any room would be negligible. Even using a higher-powered bulb of 100W would only give you around 85W of heat.

Compare that to a typical fan heater rating of 2kW and factor in that many of the bulbs will be in exactly the wrong place to heat a room – on the ceiling – and incandescents seem to be an inefficient method of heating!

4. No overall saving of energy

Some of you were concerned about the energy used to manufacture energy-saving light bulbs, but a 2009 Defra study found that incandescent bulbs had the highest environmental impact of all types of bulbs. That’s because “energy in use” is the key factor, and incandescents are much less efficient than energy-saving bulbs.

Our recent light bulb tests showed the same trait – that the most efficient bulbs were also the most environmentally friendly over the whole lifecycle of production and disposal, because energy used while the bulb is on is the most important factor.

5. Don’t tell us what to buy, give us a choice

It’s obviously annoying for a lot of people not to have a choice of which bulb to buy. But the phase-out is a “done deal” and although it forces us to buy only certain types of light bulb it does force us towards bulbs that will save us money and use less energy.

6. Energy-saving light bulbs are more expensive

The savings from energy-saving bulbs are nothing like as obvious as the extra cost of buying them in the first place, but they will save you money in the end.

We’re looking at ways to calculate payback times for all the bulbs we show test results for. In the meantime, any energy-saving bulb should more than pay for itself, but the amount will depend on various factors, especially how long it lasts.

Based on the bulb being on for 2.7 hours per day and electricity costing 14.5p per KWh, we calculate a 100W incandescent bulb costs around £14 to run for a year. An equivalent CFL energy-saver (such as the Osram Dulux Superstar 30W) would cost £3 or £4 in the same conditions, depending on how much light it emitted (watts being only a measure of how much power you pay to put in, not how much light you’re getting out).

7. CFLs are hard to dispose of

It’s true that disposing of CFLs isn’t as easy as incandescents – you can’t just chuck them in the bin because of the mercury. But we’re used to recycling much of our waste now, so isn’t it just a mind shift that’s needed to get into the habit of recycling bulbs too?

Recycling CFLs can be done at any Ikea, Homebase, Robert Dyas, 250 larger Sainsbury’s or at council facilities. Or you can find your nearest recycling points by typing in your postcode on Recolight on Recycle Now.

Do my responses make any difference to your view on the light bulb phase out? Do you think the phase out is all bad news or can you see some positives to the change?

C V Horie says:
7 September 2012

Low energy bulbs. Once again UK consumers are being fobbed off with lower quality goods. CFLs are notoriously slow to start, can have seriously low lifetimes and give out a poor quality of light. LEDs also give out poor quality of light and are expensive. If you look at your skin under some LEDs you will see every blue vein standing out, makes me look decades even older. I would not use either lamp in a situation where natual colour rendering is important, e.g. kitchen, bedroom or living room.
However, it is quite possible to make good quality CFLs and LEDs with good colour rendering. Both are available commercially in Europe and USA, but are not made available in the UK.

The halogen pseudo-low energy bulbs give a true colour rendering and a bluer light which is better for visual acuity for ageing eyes (yellowing of the cornea). So I use those.
Which has had a campaign promoting low energy bulbs. Although low energy input is one criterion, going for these lamps without considering their other properties, e.g. light output, shows an unbalanced approach. The resistance to the introduction of CFL, and predictably LED, lamps is .a sympton of a poorly thought through technology.

I am not sure what you mean by natural colour rendering. I assume this to be daylight, which is different from what a halogen lamp produces and very different from an old fashioned bulb.

There are a lot of differences in the characteristics of CFLs and LED lamps available in this country, so it is worth looking at what friends and neighbours are using before purchasing them.

For me, CFLs are a no-brainer. Old fashioned bulbs and halogen lamps have a ridiculously short life by comparison and use at least four times as much electricity. I actually prefer to have a bedroom light that does not immediately dazzle me if I have to get up in the night.

If we carry on using incandescent lamps (including halogen) we are going to have to build more power stations, unless we can make savings elsewhere or persuade people not to have so many children. The population is increasing, helped by greater life expectancy. We are all permitted to use as much electricity as we can afford to pay for, so we could all carry on with the halogen lamps that meet your approval.

A lot depends what you are accustomed to. I’ve been using CFLs for more than 20 years and I hate the yellow light of the old bulbs. I hate the popular halogen light fittings with exposed dazzling bulbs. I want to minimise my environmental impact without doing anything too eccentric, and I want lower electricity bills.

When I bought my LEDs online I found there were two colours available – warm white and white. The white, which I chose, had a slightly higher lumen output. I haven’t yet installed them so don’t know what their colour temperature is. I will let everyone know when I do.

I don’t know how true are C V Horie’s comments about the availability of different grades of light bulb in the UK as opposed to the rest of the world, although, as those of us who have been involved with the ongoing debate about dual-fill washing machines know only too well, it can happen that people in some countries can buy in their shops what we in the UK cannot. However, unlike washing machines, bulbs are cheap and easy to ship around and so, if it is the case that better bulbs can be obtained outside the UK, then surely they can simply be ordered online? Just be sure not to order them from the USA with its 110 volt supply 🙁

You are right about the different colours, Richard. I was asked to help a friend choose some LED lamps and fittings and discovered at least four distinct colours. I should note that these were 12V rather than mains LED lamps.

In addition to overseas suppliers, there are UK-based online stores that offer a variety of lamps. In previous discussions we established that two-way adaptors allowing use of two lamps in one lampholder are still available in some countries even if they have been consigned to museums in the UK.

Ah yes. I’d forgotten about the 2-way issue. I bought my adaptors from a local hardware store in Canada – where they are readily available. Sadly they are only available in ES fittings so you need also to buy a BC to ES converter (and remember to puy ES bulbs unless you also buy an ES to BC converter as well).

Although my converters are handling twice their rated voltage (but obviously only half their rated current) they have given me no problems at all

C V Horie says:
7 September 2012

Colour rendering index: If you look at the packaging of a fluorescent tube (made by decent manufacturer), you should see something like CRI: 83. This is the value of most CFLs. CRI is a value referred to a “hot (black) body” radiation source such as sunlight, daylight, candle, tungsten/halogen lamp etc. which have a value of 100. Our eyes and brains have spent millions of years adapting to these light sources. It would take a few years for them to re-evolve to adapt to CFLs.
Where good colour perception is required e.g. medical and art inspection, a CRI of >90, preferably >95, is required. These colour matching lamps used to be specified in clothes shops as well, but apparently no longer. Now when I buy clothes, I take them to the shop window to see what the real colour is in real light.
Why should we settle for unreal colours in our homes?

Actually don’t believe that the CRI is anywhere near as important as some people imagine. Indeed, it is often replaced by a different measure such as colour appearance models, such as CIECAM02 and, for daylight simulators, the CIE Metamerism Index. CRI is not a good indicator for use in visual assessment, especially for sources below 5000 kelvin.

Daylight simply does not have a standard CRI. In the morning is it much higher than it is in the evening – but we scarecly notice the difference since our brains know that, say, our grey patio is grey – even though a photograph of it taken in the morning and a photograph of the same spot in the evening will make it seem to be of quite different colours when the two photographs are viewed side by side under the same light source. Which is why, of course, good cameras have a “white balance” system.

Unless the light bulb is massively different in colour from “daylight” our brains will quickly adjust and acceot that our known surroundings are the same colour as we know them to be. Of course, for really accurate colour recognition we do need special light sources that equate to daylight – but how many people actually need such precision in their normal environments?

For those who need more information about CRI, there is a good site here – http://www.fullspectrumsolutions.com/cri_explained.htm

C V Horie says:
8 September 2012

There are indeed a number of different ways to assess how well a given light source matches the light source(s) we are evolved to use intuitively, the variable daylight and sunlight whose CRI is by definition 100. Numbers are a crude method of assessing the naturalness of light. But the further the light source diverts from what our bodies consider as “normal”, the more uncomfortable we get. Sodium lamps are at the extreme end of the scale but CFLs and other poor quality light sources add uncertainty to our normal interactions with our environment. And that uncertainty is entirely unnecessary. It results from poor choices by manufacturers encouraged by regulators and consumer organisations to produce inadequate products on a massive scale.

glynteg says:
23 October 2012

Having just read the latest repot on energy-saving light bulbs (Nov 2012), I wonder if Which? lives in the same world as I do? In spite of screw fittings becoming more common, the majority of houses in Britain still have bayonet fittings. Of the 53 bulbs tested, only 6 have bayonet fittings. Only one of those scores over 51% and that one is a halogen which scores 1 star for light output and efficiency! So it seems that if you have bayonet fittings you have no choice at all. I do not have a single screw fitting in my house, so what do I do when I need a new light bulb? What are others doing about the lack of bayonet fittings?
I am ceratinly jaundiced about energy-saving light bulbs. Here is an update to my post of 16 Nov 2011 when I complained about failures. I bought 5 fittings, each with 3 CFL bulbs in August 2011. I now have a bag of 17 failed bulbs – 15 originals + 2 replacements. The only excuse seems to be that the bulbs were a faulty batch. The shop did give me a £50 voucher to replace bulbs (only enough for 10 replacements) and 2 of these have failed. I am reluctant to replace the fittings as it will be enormously expensive but I can see no other solution.

I absolutely agree about Which? being on a different plant with regard to the Bayonet / Screw fitting issue (and a few other aspects of CFL testing).

What upsets me is that it’s over a year since it was made very clear by a great many readers that this was an issue and a member of the Which? team (can’t recall which off hand, and can’t be bothered to trawl all the lengthy convo’s I’m afraid) assured us that they would take these things into account next time CFL’s were tested.

Have they done so?

Have they heck!

It occurs to me that maybe the bayonet CFL’s on the market ( there are plenty) are so awful that if Which? tested them it would expose a lot of very uncomfortable facts about them.


We have increased the number of bayonet cap (BC) models we test in response to member feedback. Of the bulbs that are currently being put through their paces in our test lab , more than half are either bayonet caps or screw caps that have a BC equivalent. As the cap fitting is the only difference, results from a screw cap model can be applied to the equivalent bayonet cap product.

Our tests take a very long time however (due to lifetime tests) and new results weren’t out in time for the November 2012 magazine. New test results should be published online towards the end of 2012/early 2013. We are working hard to find ways to bring you results faster to keep up with the market as it is changing rapidly at the moment.

For future results, we are also planning, when we have tested the ES version of a bulb but there is a BC equivalent, to make this clear so that Which? members are aware the test results can be applied to the BC equivalent where available.

Regarding results currently online: as a general rule, bulbs from major UK brands like Philips or GE will usually have a BC cap version available (these brands tend to be stocked in John Lewis, Waitrose, Sainsburys, Wickes and Wilkinsons). Some predominantly European brands (Megaman, Osram) may be harder to track down in BC format. Ikea don’t sell BC cap bulbs.

Converters from Edison Screw (ES) to bayonet cap (BC) and vice versa are readily available and cheap. I use BC to ES converters where I have two way bulb adaptor which allows me to use two bulbs in one bulbholder. For some inexplicabe reason, these converters – once so common – are no longer made in the UK although the are readily available in the USA and Canada. Naturally they are ES hence the need for the BC to ES converter. The the lamps themselves I simply buy with an ES cap.

And the converters work perfectly – although you have to be sure to get the polarity right so as ensure that the live connection does not go to the thread of the ES fitting.

The vast majority will have the traditional bayonet lamp holder in their homes, and CFLs with bayonet caps are the norm. They are made by the same companies that make screw cap versions, so quality should not depend on the cap. The quality of the bc holder may be the issue – they would have become hot with incandescent lamps and this may have affected the spring or the contact quality.
LEDs are usually dimmable but you need normally a compatible dimmer (i.e. designed for LEDs).
There has been a compatibility problem in the past with PIRs (presence detectors), electronic timers and electronic photocells and CFLs; generally a clash between the electronics in the controller and those that are part of the CFL. As not all CFLs are the same the advice from manufacturers is to check – the information may be found on the packaging.
CFLs can be dimmed, but you need a suitable type of CFL (the packaging should say if it is suitable for dimming). GE have an FAQ section on their website http://www.gelighting.com/na/business_lighting/faqs/cfl.htm#3

glynteg says:
24 October 2012

Thanks for the info re BC -> ES converters. However these make the space required to fit the bulb quite a bit bigger. I have looked at the present lights and in most, the converters will not work. A lot of my lights are ceiling fittings with shallow dish-style shades (the house has low ceilings) and there is not enough space to fit a converter and the bulb. Heigh ho!
If as Malcolm R says, there are plenty of BC energy-saving bulbs available, why do Which? not test them? Would someone from Which? like to comment on their policy given all the comments here about BC v. ES fittings? Especially as there is not one BC bulb tested that is deemed good.

Many CFLs are available with either BC or ES caps, so it does not matter which was tested.

Happy New year (in 4 hours time) everyone.

Today I had to change two outside light bulbs – one has been out for about 3 weeks but I kept forgetting about it except after dark – that’s a 5w CFL in an enclosed fitting, cap down and the bulb that was in was Osram; the other was a 70watt SOX in a proper SOX fitting (which went out last night and makes a huge difference so I made a point fo changing that first thing this morning.

As is my habit I had written the dates of installation onto the bulb caps when they were fitted: SOX tube 16/08/2005; Osram CFL 10/10/2011.

Both lights are on a dusk till dawn sensor (same sensor, same circuit) so by my estimation are burning for about 4,270 hours in a calendar year.

The Osram CFL’s I’ve still got in stock claim “Guaranteed 8,000 hours life” …. but have in very small print various ‘conditions’ to that guarantee including “based on an average 2.7 hours use per day” and “Unsuitable for use with time switches and electronic switches”.

Of course SOX lamps are useless for in-house use and no one would ever suggest using them, but it’s pretty clear that the Osram CFL’s still are not up to much.

A Crompton CFL has gone into that fitting – it claims a 10,000 hour life and has no small print. let’s see how it does ……….

Meanwhile the Incandescent bulb in my dining room failed a few days ago – it’s a 250W lamp and to my certain knowledge it was fitted when my Grandmother lived here, and she died in 1978. I’ve replaced it with a Mazda 250W incandescent which is also one that Grandmother bought (co-op price ticket on the carton says 19 1/2 p!!!!). That’s my last 250 w incandescent spare lamp, but I still have several 200’s and oodles of 150,’s, 100’s, 75’s, 60’s, and 40’s … and I’ve NOT been stockpiling – these are what I already had before they went off sale.

Statistics can prove anything you like, so I’m not hoping to open up a whole new argument about life spans, but it’s clear to me that irrespective of the overall picture, personally I will save nothing at all by using CFL’s rather than the incandescents I have in stock, and I include in that saving the planet since my incandescents will have generated less pollution in manufacture and will generate less in their eventual disposal than the CFL’s I would otherwise buy.

Don’t get me wrong: I’m still hopeful of seeing really energy efficient lamps coming along that actually do what they say, but I still feel we’re not there yet. I have tried a few LED lamps lately though, and apart from the ludicrous price they have been quite impressive in things like the desk lamp (angle poise) and the bedside lamp (which used to eat CFL’s like nobodies’ business).

Have a good one folks: don’t all jump in the fountain at midnight (all the water will jump out!)

I changed a couple of older CFLs for cheap modern spirals to find out if the new ones are more prone to failure, but I have not any failures since well before the first of the Conversation about bulbs. I have had several failures of halogen lamps despite not using them much.

From speaking to friends and family I am luckier than many, but most are having few problems and are quite happy with CFLs, including some who were strongly opposed to the phase out of the old bulbs. What has surprised me is the number of people using CFLs with dimmers and PIR sensors, ignoring instructions. I don’t have an outside light but it’s fairly obvious to me that CFLs are not the best option.

Dave D, for your incandescent lamp to last that long, it has been running inefficiently – the 1000 hour life was designed to optimise life, light output and energy consumption.
If you need the equivalent of 250W in your living room (thats a lot or its a BIG ROOM), then around 60W of CFL will do the trick – assuming they are used for 1000 hours a year, your 250W incandescent will cost you £30 a year to run, the CFL £7. Worth the saving?

Some CFLs do not like electronic controllers – it’s to do with their own electronics. If you are using an electronic time switch that could explain short life. If so, buy a CFL that is stated as compatible (many are).

Your 70W lamp is probably a SON (high pressure sodium, orange-white) rather than a SOX (spectral orange). Although these can carry on working a long time, their light output drops considerably, so best to change around 4 years to maintain a good light output. They can also start to rectify and burn out the ballast (choke).

Hi Malcolm R.

Thanks for your thoughts and input.
The SOX lamp is most certainly NOT a SON lamp and is a Low Pressure Sodium SOX lamp – THE single most energy efficient electric light source discovered until LED started to hit the market. I’m aware of the possible damage to the ballast gear (I’m an experience and qual’d sparky and have quite a lot of experience with SOX and SON lighting) but since the fitting has been in constant use since 1984 and I only ever change the lamps when they actually fail (averaging 5.5 years over that time) I can’t complain if the ballast should start to feel a little tired (not that it’s showing any signs of doing so yet): I’ve had plenty of my money’s worth from it already. I am also in the fortunate position of having a local supplier of ballast spare parts so if I was really stuck I could actually repair the fitting should the need arise.

Re the 250 W lamp in the dining room (which is quite a big room, yes) I’m not sure that it’s been running inefficiently, but it is in the main ceiling light, which is a period piece as old as the house and completely original, and into which it is not possible to fit multiple lamps, so the CFL option is not really on. I did experiment with 30W CFL’s (the largest I was able to source at the time) a few years ago, but the light was dismal and the CFL failed after only a couple of years. Thankfully, being a waste not want not kind of guy I’d not thrown out he 250W that had come out and was able to put it back after the early demise of the CFL. I think the longevity is mainly attributable to the fact that when the light is on, it stays on for a good period, but it’s not actually on that often. That fitting would be lucky if it’s used for 100 hours a year, nothing like 1000, so highly dubious that I would make any saving with CFL, given that I’m still using bulbs that my grandmother paid for when I was a tiny kid and which only cost her 19.5p! Any financial saving from electricity consumption would be wiped out thousands of times over by the cost of buying big enough CFL’s (if I could find them) to do the job. Normally, when on my own at home, I dine in daylight hours (I never eat after 6:00 p.m. if I have a choice for health reasons) and when I have guests we have a candelabra on the table and table lamps in 3 corners of the room with 30W CFL’s in them (use to be 75W incandescents). I only use the main light if I am in there on my own after dark or when setting / clearing away for dinner parties.
Wavechange and I have discussed the various issues a lot over the years and I’m completely convinced that the short CFL life in the ceiling fitting when I tried it is due to the lamp being cap-up, hence heating up the electronics greatly and, I believe, causing premature failure. I can’t think of any other reason why the 30W cfl’s in the table lamps last around a year on average (and probably get used for about 750(ish) hours per year) when the one in the ceiling light only managed about 5 years which would have been an absolute max of 500 hours and more likely about 300.

Re the time switch – not a time switch: standard Photoelectric cell as fitted to street lighting, switching a contactor which in turn switches the SOX lamp and three other outside lights all of which have CFL’s in them. It’s a proper coil contractor, not a triac device, so that’s not the issue with the CFL, but as Wavechange has often said, and has added above, it seems pretty clear from many and diverse sources, including Crompton’s own web site, that CFL’s (standard ones) are simply unsuitable for outside lights. However, much as I value your suggestion for buying “compatible” cfl’s, I’m afraid that experiences posted by others many months ago would seem to suggest that it’s no guarantee of actually prolonging the cfl’s life to meet the advertised hours.

The biggest problem, to be honest, isn’t the life span of the CFL’s, it’s the cost of buying them and most of all the impossibility of disposing of them correctly. If incandescents only lasted as long as the CFL’s I’ve had bad experiences with most of us, certainly I, would think nothing of it, and because they are easy to dispose of I’d not worry either, but CFL’s are such a variable feast (sadly varying too much towards disappointing) and disposal is so hard to do correctly, that the shorter life becomes a major issue.

I do have to say, though, that I think the 1,000 hour left of incandescents was probably a rather conservative estimate. Take a look at the John Rylands LIbrary in Manchester. That was first fitted with electric light in 1900. In the late 1990’s they rewired it and it was found that a great many of the lamps in use in the chandeliers, etc., were the original bulbs fitted in 1900. It’s a public library, open virtually every day of the year and with the lights on all through the opening hours. my mental arithmetic isn’t up to making an instant estimate of how many thousand hours those lamps had burned without failure but it was way over 1,000!

Wow! that’s along reply to you!
Thanks for your thoughts and suggestions, and Happy New Year!

Just had a look back at this convo for “nostalgia” and noted that Richard Dilks (of Which?) posted the following:

“Just popping on to say we’re going to look in more depth into the issue of how easy the energy-saving bulbs are to recycle.
Posted 21 October 2011 at 2:03 pm”

I’m wondering if now, 15 months on, he or anyone else at Which? has made any progress with the recycling issue? If Which? has published anything on this I’m afraid it’s passed me by, but I can tell you that in Sheffield the position is unchanged and that all my dud lamps go straight into the black wheelie bin, against every law and regulation there is, wrapped inside other waste to avoid detection by the bin men.

Any joy yet Mr. Dilks? Do let us know what’s happening.

why bother wrapping, no one really gives a damn

wavechange, CFLs can be used outside, although if it is very cold they might have trouble starting (say -5C), and their light output is reduced at low temperatures. They are also not great at being switched repeatedly at shortish intervals. But if run for reasonable lengths of time in a small enclosed light fitting that allows the temperature to rise, then they’re OK. LEDs are the better bet, but more expensive.

I take your point but I suspect that bulbs used outside are failing during the time taken to reach normal operating temperatures. I have read that CFLs have circuitry that shuts off the power to prevent overheating at end-of-life and perhaps this is being activated in good lamps expected to start up at low temperatures. I don’t have circuit diagrams for modern lamps to be able to confirm this. CFLs are just a form of fluorescent tube and need the correct mercury vapour pressure to operate correctly, which is why none work particularly well when first switched on in the cold.

Interesting – I replaced all incandescent lamps with 11W Phillips CFL in 1980 – I have 9 rooms plus a hall.and an Attic/Loft Only 3 of them have have actually ‘burnt out” – But some Philips were unsuitable as they were too heavy or too dim even with thinner shades. So I changed these with lighter and/or quicker brighter lamps like the newer 18W CFL which I bought as a pack of 12 very cheaply on Ebay. Still have 10 left. I always had reading lights where necessary – but now I am satisfied with the light output overall. I still have single 80W long fluorescents in the work shop and kitchen as the overall light is still far better than CFLs or LEDs.

wavechange, there are fluorescent lamps (linear and CFLs) designed specifically for low temperatures with a mercury amalgam.

I have not encountered low temperature CFLs, though I have seen them advertised. If they are genuinely better then anyone with an outside light needs to know about them. I stand to be corrected but I believe that use of mercury amalgams is commonplace in CFLs, and the purpose of using an amalgam rather than free mercury is to stabilise the vapour pressure of mercury in the lamp.

Just an update on the LEDs I bought to replace the expensive and inefficient Quartz Halogen bulbs. They are bright, white, start instantly and can be dimmed – although the dimming is not so good as it was with incandescants. They do make a slight buzzing noise in operation but that is not noticeable in normal circumstances.

They are rated at 8 watts and are supposed to last even longer than CFLs. So the purchase price of around £12 each will be written off in about a year.

I suspect that the purchase price will drop once mass-production and consumption really gets cracking. But it will be a while before I need to buy any more as I expect it will take some years before my stock of CLS is used up.

Another contributor pointed out that not all LED lamps can be dimmed. I have also heard that some LED lamps can interfere with FM and DAB radio reception, but others are better in this respect. I guess there is still a lot to learn but the improvement in performance and falling price is very encouraging.

Since LEDs provide a directional light source they are ideal as replacement for halogen downlighters.

Indeed. And the non-dimmable LEDs do cost a bit less than the dimmable ones. I have to say that the LEDs I have are not all that directional – although more so than incandescents or even CFLs. This seems to be a characteristic of the larger proportion of the LEDs that are is for the electronics

Appros Dave D’s comment about the life of incandescent bulbs – if you underrun an incandescent it can last for many. many years. There is an incandescent bulb in California that has been burning continuously for 110 years – http://www.centennialbulb.org/ – But as the pictures clearly show, the light output is miserable simply because it is being underrun.

The strange thing is that people worry about the lifetime of their bulbs and tend to blame the manufacturers for making bulbs that fail too soon but this is just not the case. The electricity costs far, far more than the bulb and the 1000 hour flourescent is a good compromise between output and life. If you want your incandescents to last for ever, just wire two of them in series and they will never fail. You’ll only get less than half the life for the same electricity cost, of course – but it’s an easy enough fix.

Better by far, though, to abandon Joseph Swan’s clever invention and replace your incandescents with Oleg Vladimirovich Losev’s invention, the LED. Sad though it is to abandon such a wonderful British invention, the incandescent light bulb, for a Russian invention – but, hey, Swan’s bulb has a very good innings. Even the Americans started using them.

CFL – and linear – the formulation of the amalgam determines at what temperature the optimum light output is achieved. I do not know if the household CFLs – i.e. with an integrated electronic controller – are available in cold temperature form. Those that require a separate electronic ballast are. The latter are much more sensible lamps to use – you don’t throw the electronics away when the lamp fails, and the ballast is more sophisticated. However, not retrofit in a BC or ES lampholder. Why on earth someone doesn’t promote domestic lights with them escapes me.
LEDs – are basically a chip that emits light through 180 degrees in a Lambertian distribution – i.e maximum at right angles to the chip, and minimum parallel to it. But they are usually sold with a lens on the front that gives it more directionality. All LEDs can be dimmed, but it depends on what the integral circuit is that is used to control them as to how an added dimmer will perform. Essentially they are current-controlled devices, with light output proportional to current.

The other advantage of separate electronics is that they can be kept away from the heat generated by the lamp, potentially offering the reliability of fixtures using fluorescent tubes.

When CFLs were introduced it was obvious that domestic users needed a direct replacement for incandescent bulbs. I had hoped that we would see domestic fixtures with integrated electronics and replaceable lamps appear on the market but feel we have been let down by the manufacturers of fixtures. I share your disappointment.

Domestic lamp dimmers use phase control and that is not a satisfactory solution for standard CFLs and some LED lamps. Without the restriction of having two wire supply to the lamp it would be very easy to produce much better dimmers.

Gixer says:
14 February 2013

Just fitted a dimmer switch in the lounge, and when first switched on the bulb flickers for a short time (10 to 20 secs) before being okay! Any suggestions to why it’s doing this…….I’ve re-read, and re-read the wiring instructions, and it is wired correctly!!

If you read the instructions that came with your lamp it will say that it is not intended for use with dimmers. Dimming may overheat or destroy the electronic circuitry of your lamp, or dimmer, or both – but that depends on design.

The lamp flickers at low brightness because the heaters at the ends are not hot enough to emit enough electrons to produce a stable discharge. In lecture theatres, etc., fluorescent lighting can be dimmed very effectively by keeping the heaters hot even when little current is passing through the lamp. Unfortunately this cannot be done with domestic compact fluorescent lamps that are connected via only two wires.

Some (not all) LED lamps work with dimmers, but a good way of dimming lighting is simply to use smaller bulbs in table and standard lamps.