/ Home & Energy, Technology

The energy-saving LED bulb that switched off the radio

An LED bulb lighting up the darkness

We get sent some weird and wonderful tales of products going wrong, but one story piqued our interest so much that we just had to send it to the lab to test it out. Can you help us shed more light on the mystery?

Last year we received this intriguing message:

‘I recently changed six halogen down-lighters to more energy efficient LED bulbs. Unfortunately when the lights were switched on, the DAB signal on my radio was wiped out!’

To try and figure out this conundrum, we sent a batch of cheap, generic 12V LED bulbs to our lab and found that when a digital radio was placed within a few metres of the switched-on bulbs the signal went fuzzy. When the radio was placed within a few centimetres of the LED bulbs, it cut out all together.

The plot thickens

LEDs are ultra energy efficient light bulbs that can last up to twenty years and have been hailed as the future of home lighting.

It seems our members are not the only ones who have had this problem. There are other accounts of LED bulbs affecting radios, with AVForums also collecting stories. Nick Tooley shared his experience:

‘I had the same problems with LED bulbs wiping out DAB reception and tried several types of bulbs, but to no avail.’

And it seems that the issue may not just be limited to digital radios – TVs may also be affected. After fitting LED down-lighters in his kitchen, Jackord noticed the following problem:

‘While the lights are much better, we then by accident noticed that the digital TV would not work (I was complaining that we had no reception at all, did not make any sense, began to think that there had been some sort of catastrophic disaster which stopped the TV stations from broadcasting…lol) then someone turned off the ceiling lights in the kitchen and, hey presto, on came the TV.’

Shedding light on cheap bulbs

So what bulbs are affected? We tested three 12V generic LED bulbs and we also compared them to branded 240V GU10 LEDs and some halogens. We found only a very minor interference with our radio signal. So at this stage, the issue seems to be limited to cheap knock-offs rather than branded goods.

We’ve only done preliminary tests on this problem, so can’t make any concrete conclusions on why this is happening or how widespread this bizarre problem is.

That’s where you come in. We need your help – have you had this problem? If so, please enlighten us in the comments below, including what model bulb you were using and where you bought it.

Jim says:
29 March 2013

I have a Chronos DAB radio which is on my desk I also have an LED desk lamp , whenever I turn on the lamp my radio stops working. I assumed that it was noise from the lamp cable which runs parallel to the radios power cable was causing the interference. Just for reference the lamp has none replaceable LED lamps.

Mike says:
29 March 2013

It would be a shame for the consumer acceptance of more efficient lighting products to be damaged by a few rogue manufacturers flouting the regulations (and getting away with it). In the last few months I’ve bought twelve 3W GU10 (230V) LEDs from Lidl and Costco for £5 to £8 each. None of them has caused any interference with my DAB radios, so it’s not a universal problem, and it’s not just about price.

We know the authorities will not do anything about policing the regulations, so what we need is a more organised way for consumers to share information about good and bad products. There is a lot of discussion in forums spread all over the internet, but it’s time consuming to get the big picture, people complaining often don’t give enough specific information, and good products are less likely to get a mention.

Perhaps Which? should consider a creating a database of consumer experience fronted by a detailed questionaire, rather than running a vague and woolly discussion thread.

Thanks for taking part in this fascinating debate. We’ve rounded up a selection of your comments, including picking our Comment of the Week: https://conversation.which.co.uk/energy-home/your-view-led-bulb-interference-dab-radios/

Roy Birkby says:
29 March 2013

I use LED lights throughout the house, some are GU10 and some are MR16 I also have some bayonet types. I have had not problems whatsoever but I buy tbem from Simply LED made by Burton and Sons. They are very well made and a not cheap in any way. I recommend the products from this company

Roy Birkby

Barry Smith says:
29 March 2013

LED Lighting
GU10 Led lamps –
Two versions of these have been examined, they use capacitive reactance as part of their power supply. These run cooler than purely using a resistive type.
Sources of this type information can be found at:
http://www.zen22142.zen.co.uk/ronj/tless.html although the one shown is for a 12vdc supply the principle still holds good for higher voltages. The key formula is XC = 1/6.284 x f x C = about 6.8Kohm
One divided by two Pi x frequency (50HZ in this case) x Capacitance (0.5 micro farad).
My thanks to Ron.
Due to mechanical failures I have had occasion to look inside 2 different GU10 LEDs.
The capacitor in parallel with 500Kohm is in series with a full wave bridge rectifier (made up of 4 seperate diodes) the DC output of the bridge rectifier has an electrolytic capacitor & a resistor across it, in one version 2.2micro farads, in the other 1micro farad. The output voltage is about 240vdc
One used 80 x 3 volt leds in series which = 240v, the other had 20 chips each with three leds at 4v each. 3 x 20 x 4 = 240v.
It could be that it is the capacitors 90degree out of phase charge / discharge cycles that generate the RF noise. A very crude power supply.

Mike says:
30 March 2013

Interesting information from Barry about the capacitive ballast in his GU10s. But that type of circuitry would only be used with lamps that have a large number of low current LEDs in series. My GU10s have three high current LEDs and use a medium frequency switching regulator to convert 230V AC to low voltage DC. The only RF noise source in Barry’s lamps would be the full wave rectifier’s diode switching noise which seems very unlikely to interfere with a DAB radio – although it could be audible on a long wave AM radio. Switch mode regulators are far more likely to interfere with DAB, but only if they are poorly designed and cheaply made. Although in very marginal signal strength areas even a small amount of noise might tip the balance. DAB reception does drop out very abruptly.

roger_lec says:
30 March 2013

re the Roy Birkby comment above:

I have just installed 3 x 5 watt 12volt MR16 non-dimmable LEDs (NxtGen, product code MR16-RCSPOT) from Simply LED (Burton & Sons) connected in parallel as recommended to an Aurora 12volt 16 watt constant voltage driver (transformer) (model AU_LED16T) as part of a kitchen renovation, and there is constant DAB and FM radio interference when these lights are on. Alas, I’m abandoning any further LED installation and shall have to revert to halogen. Reading the web, there seems to be no convincing solution to this problem so far, and it seems to be widespread (and I’ve never seen it mentioned in any LED lighting PR!)



Hugh Roberton says:
30 March 2013

In my kitchen I have a Pure Evoke-1 with an extension speaker. It worked well up until the start of the first snow last year. I also lost the stations on my Pure Sonus 1XT in my bedroom at the same time and would have to auto tune after every time I switched it off. In the beginning I thought it was the extreme weather conditions that were knocking out the signal but after the weather improved it was still a problem. As an avid listener to radio I began to get annoyed and so researched on the Internet where I discovered forums discussing LED interference. I remembered I had installed 1 Led spotlight in the kitchen and found if I left that bank of lights off the DAB radio came back in the kitchen but the Sonus is still a problem. I sent an email to Pure customer service over two months ago and there is a stunning silence from that end.

Andrew Entwistle says:
31 March 2013

I have found that of three different types of LED 12V MR16 replacements only the cheapest emitted significant RF interference to analogue FM radio. However the dominant source of RF interference in our house is the electronic ‘transformer’ that supplied the original halogen MR16 lamps. Its more modern and branded replacement designed to supply LEDs still causes a squealing noise on even the strongest stations, such as Radio 4.


We’re granted official super-complaint powers by the Department of Trade and Industry, giving us the power to make super-complaints to a number of government agencies about markets that are failing consumers”

Surely Which? can use its powers mentioned to actually harness the membership voice as we are all affected. And as far as I can see I cannot see any bad “unintended consequences” from this action unlike the Gender Directive on car insurance.

I am surprised in a way our more technical cousins the Germans have not already highlighted this area …. or is it just possible that no uncompliant devices are sold in the German market.

Which? please advise soonest.

I will willingly forgo any chance to complain in a Which? stories about mayonnaise fillings in sandwiches and suchlike : )


I believe that the problem with interference produced by LED lamps and other domestic items is one of the best examples of failure of CE marking to provide assurance of conformity to standards put in place to protect the consumer. I think this bigger issue is what Which? and other consumer organisations in the EU/EEA should be tackling, though your suggestion might be a good high profile way of making a start.

Electromagnetic radiation and mayonnaise have something in common since the latter – in various guises – is becoming unavoidable. I have just learned that the confounded stuff was invented by a German. 🙁


An interesting read and no German mention!!

Why bring in yet more confusion?! This would seem to be another contentious topic – just as well those in the after life don’t have access to iPads….or do they?

History of Mayonnaise
inventors.about.com › … › Inventors › Famous Inventions › Food ProductsCached – Similar
In 1756, mayonnaise was invented in France by Duke de Richelieu’s chief. In 1905, the first ready-made mayonnaise was sold at Richard Hellman’s New York

en.wikipedia.org/wiki/MayonnaiseCached – Similar
Mayonnaise often abbreviated as mayo, is a thick, creamy sauce often used as a condiment. It originates from Mahon (Spain); in Spanish Mahonesa or …

Who invented mayonnaise and shaving cream
wiki.answers.com › Wiki Answers › Categories › Cars & VehiclesCached – Similar
Who invented shaving cream? George Washington Carver. Who is credited for inventing mayonnaise and shaving cream? back to at least 1756

Can one of you correct the information on Wikipedia, please:
“In 1905, Richard Hellmann from Vetschau, Germany, opened a delicatessen on Columbus Avenue in New York City, where he used his wife’s recipe to sell the first ready-made mayonnaise. It became so popular that he began selling it in bulk to other stores.”

Can we get back to the LED bulbs? We seem to have been suffering interference from mayonnaise.

V Martin says:
31 March 2013

Led lighting interference – it is necessary to convert 240Vac mains to a low dc voltage to drive the LED diodes. Most probably the makers use switched mode power supplies to preserve efficiency.
The internal chopper frequency will be high to achieve small size. If badly screened this could fall in the DAB or FM band or the reception band of any receiver. Are offending products CE marked. If so either the testing specification is wrong or the test not accurate. Why doesn’t Which send a sample to a competent EMC Test Lab preferably one which can also do CE certification? A good sample would allow diagnosis of the technology but a bad sample would show the problem.

Mike says:
31 March 2013

The CE mark doesn’t mean the product has been tested, it means that the manufacturer claims that the product meets applicable regulations. Manufacturers selling cheap no-name products may put the CE mark on so that they can export them to Europe, without even attempting to meet the regulations.

My Lidl lamps (which don’t interfere) have GS and TUV marks in addition to CE, which means that they have been tested to German quality standards. That may be why the Germans don’t have an EMC problem (assuming that they don’t).

So is the quick answer for the UK Govt/Trading standards to say only GS and TUV marks be sold. Or at least Which? check this is the right way to go and actually heavily advertise the fact that CE is a worthless, or at least very indifferent quality mark!

A splendid start to what will be a long campaign no doubt as more people go digital and run signal through their home electric circuit.

Arrick Wilkinson says:
31 March 2013

We are in the procesDs of moving house and, when in B & Q saw led lamps that were daylight temperature; we purchased two of them for the two bedside lamps we have. These two lamps are both plugged into the same 4-socket extension cable roughly at the centre of the all where the headboards of two immediately adjacent single beds.
When I switched on my bedside lamp, which is about six inches from the DAB radio, the radio totally cut out. With my lamp switched off and the same type of bulb in the other bedside light we get an unlistenable-to tweeting on any Digital Radio channel. After reading your article I replaced the led lamp into my bedside lamp, then moved it away from the radio, roughly parallel to the bed edge. Once the distance reached about 24 inches, the reception was fine. The DAB radio has a vertical wire aerial running up the wall. But the problem with the other light – 8 feet away is still there, both with the original led lamp or with the one from my side of the room which didn’t interfere when 24 inches away. I then tried rotating the DAB radio to check if that made any difference to the tweeting. I did this in approximately 22.5 degree increments, all with no effect.
The lamp is not a cheap one (I think they were £14.95 each, nor an unknown make – they are OSRAM CL A 40 M3, model E27 screw fitting and with a CE symbol present. If you think I have missed out any important or helpful information, please contact me.
I had not realised that this was such a wide-spread problem. Keep up the good work.

Ignoring the possibility of interference via the mains supply, the problem will be very much greater if the source and receiver are close together. The inverse square law applies. Try to keep your radio as far away from the source of interference as possible.

You could try replacing the more distant light with a compact fluorescent lamp.

Possibly a better bet anyway would have been CFLs, about as efficient, cheaper, and fairly long life?

One issue is whether there are in place suitable IEC / EN standards covering LED supplies. I have asked LIA and CELMA – see what they come up with.
CE marking – the only way to fully support CE Marking is to require manufacturers and importers to have third party testing carried out to show compliance with applicable standards (if such standards exist). Marking with the test mark also requires audit testing at the manufacturer to ensure proper quality standards are maintained. Even so, it is still possible to cheat the system (e.g. by altering the design without disclosing). In practise, to have every product range tested in this way may well be beyond the capabilites of test houses, and inordinately expensive for smaller reputable manufacturers who produce and test genuine products.
One way to deal with this should be a decent policing system – consumer organisations seem best placed to deal with this by acting as a data base for reports from members and then taking offending products to “the authorities” for investigation and to impose sanctions where appropriate.

I think a more practical solution would be to encourage consumers to return products that are unsatisfactory – for refund, including postage where appropriate. The problem is that most of us are prepared to put up with second rate products.

The problem is most consumers will not know where the problem lies, and inertia will prevent most from acting. Certainly those who do know better should return defective products but also inform an organisation that is prepared to tackle the problem as a whole.
The answer is really to prevent more of the defective products from reaching market when a serious problem is uncovered.

I agree that we need to prevent defective products reaching market, but there seems little sign that Trading Standards is tackling the problem, even in the case of counterfeit dangerous products. As we know, they don’t have the resources. The growth of online trading and the willingness of people to buy products that are very cheap has exacerbated the problem.

Perhaps those of us who have some idea of our rights and the confidence to take action should encourage friends, family and work colleagues to return defective products.

Since buying an unsatisfactory and potentially dangerous product through Amazon Marketplace, I have been giving thought to how to publicise the problem. Both Amazon and the trader did not care and I’m taking up the issue with Trading Standards again, since the product is still on sale. Who else should I inform? How much effort should I devote to complaining about something that only cost £9.15?

If we buy LED lamps and suffer from interference we can get our money back. But which organisation should be informed that there is that problem with this make and model of lamp?

As I have suggested earlier, the losers in this, apart from consumers, are the responsible manufacturers. I think their trade organisations should have the incentive to take action to protect them. Has Which? discussed this with the LIA or CELMA?

CE is a Safety Mark applied by the manufacturer / distributor to claim compliance with an applicable safety standard (quality refers to the manufacturing systems that are adequate to maintain the safety of products manufacturered, not quality in the sense of “goodness”).
Any European country’s Test House certification allows the country quality symbol to be used – in the UK BSI issue the Kite Mark. All testing is done to European Standards so any European Mark is good enough.

puffpod says:
1 April 2013

I’ve not noticed our under cupboard led strips affecting our kitchen DAB, but having the kitchen LED TV on completely destroys the DAB signal.

Yes indeed puffpod, many TV sets radiate interference; LED lamps and TVs are just two of many products causing pollution of the electromagnetic spectrum. The whole situation has got right out of hand.

Indeed, Richard. In Victorian times, manufacturers treated rivers as being convenient places to dump their polluting rubbish and now they are treating the electromagnetic environment in the same way. It took a very long time to clear the rivers of pollution but I suspect that cleaning up the e-m environment will be a very much more difficult task. It may, in fact, be impossible given the scale of the problem and the rate that this is getting worse.

That is an excellent analogy. The big problem is that very few people understand the issues or even know about them, which makes fixing it pretty well impossible at the present time.

Agreed. To some extent the LED lighting problem is useful in that it has brought the e-m situation to the attention of the wider public. The start of the Which? report highlighted the problem of getting the general public to understand: there was astonishment that LED lights could cause a radio to stop working!

Tonyp – Until people experience a problem it does not really feature in their concerns. I became aware of interference repairing radios in my late teens, where car ignition interference and mains hum were problems. I learned that I could create interference problems by making inverters and capacitative discharge ignition systems before I saw them on sale. None of that prepared me for the many interference problems that I have experienced later in life, though I can understand why a switched-mode power supply, a CRT, a microwave oven and a LED lamp can produce interference. The biggest surprise of all was being unable to use the central locking on my car whenever I parked in a particular spot. I was vaguely aware of the problem but it certainly had not registered until I experienced the problem for myself.

When LED lighting becomes common, everyone may understand that it can cause radio interference. Perhaps the answer is to hold off buying for the present time, until the problem has been addressed. It is not good that the public has to put up with anything that is not ready for the market. We have seen enough of this with computer software.

I very much support what you have said about the difficulty of removing interference. We need prevention not cure.

My main concern, wavechange, is that people will consider LED lighting to be the only problem area when, in fact, it is actually not the most significant source of the e-m pollution that exists.

I have had a long involvement in emc matters as the head of an R&D department working on safety-critical avionic systems. As can be appreciated, emc is of great importance and such considerations pre-date the EU EMC Directive by a very in long time indeed, there are very well established international specifications in this area. As a member of several committees involving industry, MoD, CAA and DTI I was very aware of the implications of e-m pollution on aviation. These problems are increasing and there are now some very serious concerns about future developments. Probably the most significant is the increasing use of power line data transmission systems, especially as the data rates get ever higher.

Most people will only think about LED lighting or whatever else has caused them a problem. You are a specialist and it’s understandable that you take a broader view. I hope it will not need news reports of disasters to raise awareness of the consequences of our modern lifestyle coupled with poorly designed equipment may be more than the inconvenience of radio interference.

I am not sure how we should proceed, but it’s clear that public needs simple advice, even though the subject is complex.

I have asked the Lighting Industry Association for their views on this issue. They have already sent me a comprehensive list of Standards for LEDs, including 3 EMC, so I am waiting to see what is applicable to LED circuits. I will pass on any useful information.

Do you know if LIA or CELMA would be interested in receiving feedback from the public, Malcolm? A Web-based form could be used to collect information.

I’ve asked the LIA – I don’t expect an answer until next week. My suspicion would be that if they are interested, someone like Which might be best to collect information as they have the online surveys, then collate it and pass it on. Have Which already considered how they might deal with the problem?

Nigel_Essex says:
2 April 2013

This discussion should not be focussing on the radio when it’s the lamps that are at fault. Electrical products should carry the CE mark and part of that certification covers electromagnetic compatibility (EMC directive). If the lamps carry the CE mark but don’t conform they should not be on sale. If they do conform, yet still create interference, then the directive needs t be improved.

David says:
4 April 2013

I have just purchased 5 x GU10 LED bulbs from LightBulbs direct. These are Crompton Non dimmable LED 5W Cool White. I fitted 3 of them in my kitchen and switched on to see the effect. My DAB radio suddenly began to “burble”, interference which disappeared as soon as I switched the lights off.

KenA says:
5 April 2013

I have 4 under cupboard eyeball downlighters in a caravan, at the Malvern show last year I bought 2 LED bulbs as a direct replacement (similar bulbs to a car’s tail light bulbs) to try. I thought the light was good and they produce much less heat. However my Pure Elite DAB radio is affected; it cuts off when the bulb above it is turned on. If I switch it off the radio returns until someone walks between the bulb on the other side of the caravan and the radio. This seems to conduct the interference and the radio goes fuzzy or cuts out.
I assess electricians and have seen the upsurge in LED light fitments in kitchen ceilings etc;, when I ask none of them report problems with radios, even when I see DAB radios in the kitchens that I am assessing in. We are still at the early stages of LED lighting and feedback to manufacturers should see improvements in the comng years, especially with dimmers, which is yet another problem.