/ 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.


Can anyone say whether the LED lamps that operate on mains voltage are more or less prone to producing interference than the 12 volt ones that operate via some sort of voltage converter (which is more likely to be a switched-mode power supply than a transformer nowadays)?

Gary Myers MIET MBCS CITP says:
27 March 2013

Mains powered LED lamps are more prone to creating interference (QRM) due to the issues surrounding the lack of filtering with some switched-mode power-supplies. Further interference can be created if the lamp uses a buck-driver (another form of switched-mode power-supply), or some other form of switching regulator that lacks any filtering.

12V LED lamps that use a buck-driver are capable of creating a great deal of interference, and many suppliers mistakenly believe they do not have to test low-voltage lamps for EMC compliance.

An interesting example: I purchased some after market 501-wedge-style 1W LED lamps to use in my car. These were buck-driven, and when I switched my side-lights on, my C.B. radio was wiped out. The switching regulator worked around 5kHz, yet it was capable of generating considerable harmonic interference up at 27MHz (and possibly higher). They were replaced with resistor-limited solutions.

Resistor-limited 12V LED solutions do not cause any interference – unless powered from a non-compliant power supply – and these are now my primary choice (and recommendation) for in-vehicle (and in-caravan/boat) usage. There are some resistor-limited 12V LED solutions available to replace small halogen capsule lamps, although the amount of energy saved is probably negligible. Some MR16 solutions I have seen are resistor limited, and should not produce any interference. Other models would need to be tested and/or cut open to check.

Yes, that makes sense, though I’m not sure that QRM will mean much to anyone who has no involvement with ham radio, etc. 🙂

Switched-mode power supplies are very common and don’t usually cause radio/TV interference, so I cannot see any excuse for 12 volt LED lamps causing interference. As Ade has mentioned below, they can. I cannot see the obsession for LED lighting for use in caravans/boats, where fridges and freezers use a lot more power.

I do feel sorry for manufacturers trying to produce mains voltage LED replacements for incandescent lighting because there is so little space available to produce an efficient product that does not generate interference.

Graham Bedwell says:
28 March 2013

Well designed and constructed switch mode power supplied do not produce a lot of radio interference, but many CE. “approved” cheap and nasty devices do cause a lot of interference over a wide area .
There has been a case of computer power supplies having the suppression filtering components deleated and the printed circuit board fitted with by pass wires in the filtering positions , but still CE, approved !.

Regards from Graham,.

Graham, just to stress the status of CE marking. It is not an (independent) approval, simply a statement that the manufacturer claims compliance with the relevant EN standards. CE marking was introduced to allow the free movement of products throughout the EU, in place of each country requiring compliance with it’s own local standards – harmonisation. Totally right in principle but difficult to enforce against rogues until a big problem is exposed.
The reputable manufacturers will ensure through testing and assessment, and often third-part testing, that they are in compliance. The EN equivalent of the BS Kite Mark does require independent test house approval.
Others – including importers from non-EU countries, have to also comply with standards and show this by applying a CE Mark. They may not comply of course, and the policing system seems very poor at picking up such products. The best route seems to be for Consumer and Trade Associations to determine where products are deficient and pursue the authorities to take action.

I do wonder how many companies are fined for lack of compliance. Producing decent quality compliant products costs money, so producing second rate products at a more competitive price may make good business sense. Any fines can be written off as a business expense and the biggest risk could be loss of reputation. I have lost confidence in CE marking. No doubt all the non-compliant lamps we have been discussing are CE marked.

A bit non-specific, but we’ve had 3 lots of LEDs installed recently – normal (i.e. 240v) LEDs in a shower room & the kitchen, & low-voltage LEDs in the bathroom (all done by different installers). The only ones causing problems are the low-voltage ones, which prevent digital radio reception anywhere within a 5m radius of the bathroom when switched on – I can only assume that this is due to the transformer & not the bulbs themselves.

Thanks Ade. It might be useful if everyone reporting a problem was to mention if they are using mains or 12 volt lamps.

Gary Myers MIET MBCS CITP says:
27 March 2013

Readers of this forum might be interested in reading this PDF from EMC testing-house METECC:


They have carried out extensive testing on a range of LED lamps, found most of them failed EMC compliance tests, and found that no-one wants to take responsibility for it!

Which? – you have been contacted on this before – as detailed towards the end of the report!

It kills FM radio too, in my experience, and the authorities don't care about non-compliance says:
28 March 2013

I tried to be green, and bought some 12v MR11 LED spots for our kitchen downlighters. Switched them on and Radio 4 went to white noise on the portable VHF FM radio on the kitchen table. It happened with the ceiling light points (daisychains of 3 lights from high-frequency transformers) and equally badly from plain 12v magnetic transformers (50Hz). Just one MR16 LED at 12 feet jammed the radio signal. The first LEDs were from Amazon supplier “LED factory outlet” – lamps had no labelling on at all, boxes said little about brand or spec other than 12v Warm White 5W but did have “CE” printed on. They went back for a refund straight away. Then I bought ten from a UK source, BeamLED, who claim to design their own and meet all required standards – same problem. These were marked 12V 50Hz CE. Had to work harder to get a refund from BeamLED and got whitewash answers to complaints. Then contacted the BBC & found this is a well known problem throughout the EC and that while 70% of LEDs fail compliance tests, the compliance tests themselves are inadequate – they don’t test for conducted emissions, ie. what goes up the wire to the transformer – and this wire acts as the aerial for the interference. People in authority simply don’t seem to care about non-compliance, seem to think getting your money back if dissatisfied is an OK solution!!

My recollection of EMC testing was that it dealt with both radiated and conducted emissions. Is that not correct?

John Dalton says:
28 March 2013

In terms of the General Directive on EMC I think you’re right. But the various EN standards applying to light bulbs don’t specify conducted emission testing. An EC report pointed out this omission and suggested using the conducted radiation test as used for fluorescent luminaires – which is an analogous “system of components”. See http://ec.europa.eu/enterprise/sectors/electrical/files/emc/ms-campaign-fourth_en.pdf (PDF file)

Thanks John – my experience was with discharge lamp luminaires.

Mains voltage vs 12V types says:
28 March 2013

While I’ve failed to find any 12V MR16’s that don’t kill the radio, I’ve had no problem with a variety of battery LED torches (all seem to use 4.5v, 3 cells or 3.6v single rechargeable lithium cells) or two samples of 240V LED GU12 lamps. You’d think mains voltage would be a harder problem, maybe the manufacturers just took it more seriously!

John Dalton says:
28 March 2013

Sorry, put a tile in my last two comments instead of my name!

Deckard says:
28 March 2013

WITCH readers and UK consumers take on trust that the markings and approvals associated with products they buy are meaningful and accurate.

This is NOT SO with an increasing number of items subject to EMC (Electro Magnetic Compatibility) legislation.

The EU has placed the responsibility for monitoring and enforcement of the appropriate EMC standards to the sovereign state. In the case of the UK it is Trading Standards and Ofcom.

As you are no doubt aware Trading Standards has limited financial and technical resources, and so has to call on Ofcom where EMC matters are involved. Very rarely does Ofcom assist.

Although mandated by the EU to conduct Market Surveillance on electrical products, Ofcom does none. Further, when evidence of non-compliance with standards is found, Ofcom takes no action.

Consumers have seen the effects of poor regulation in the UK. The FSA and Health Authorities being recent examples. Ofcom, when it comes to EMC makes them look like saints…

Public Safety and National Security are also in jeopardy – but that’s another story !

CFLs (compact fluorescent lamps) attracted a huge amount of criticism when the old incandescent bulbs were withdrawn, but radio interference was not often mentioned. No doubt some people are happy with their LED lamps but those planning to install them may be wise to wait until the interference problem has been resolved. If nothing else, the high power LED lamps are likely to become much cheaper.

Wavechange is sticking with his good old CFLs for the time being – thanks to this Conversation.

john dyos says:
28 March 2013

kitchen led down lights cause interference on the pure dab radio

John Dalton says:
28 March 2013


Sorry to know this issue. yes, our this bulbs in best seller top 100, to be honest, I really first time got the report as has noise on FM redio. It’s strange. please feel free to return them to our warehouse for us to examine. They are 50/60Hz, and CE&ROSH. I enclosed our feedback page for your reference on amazon.co.uk as we were selling on
amazon.co.uk almost 1 year, the amazon.de just few months. But you also can see 100% feedback on amazon.de. http://www.amazon.co.uk/gp/aag/details/ref=aag_m_fb?ie=UTF8&asin=&isAmazonFulfilled=&isCBA=&marketplaceID=A1F83G8C2ARO7P&seller=ASYOZ3C9ULU1M# I am on holiday in Sweden until Jan 2013, so please send those bulbs to below address, we will refund you when we get the return.

41, c/o Sky Town Apartments 2
Rekrytgatan 15
582 14 Linköping
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David says:
28 March 2013

The Radio Society of Great Britain which represents the licensed Radio Amateurs throughout the Uk has been testing these lights for some time and has has discovered that many of them simply do not meet EU regulations and should not be on sale at all.

Dave G0IXZ

Ralph Stern says:
28 March 2013

We recently moved here and our electrician persuaded us to change to energy saving lights. He used Robus R3MRCLED-WW. 3W MR16 MULTICHIP LED LAMP. With the lights on we had considerable interference with our digital radio, as soon as we turned the lights off reception was excellent. Once our electrician changed to bettter bulbs we had no more interference.

John Dalton says:
28 March 2013

That’s interesting – I’d very much like some MR16’s that don’t interfere with my radio. Do you know what make/model he replaced them with? There may be branding on the base by the pins. I’d really appreciate if you could find out for me! – John

Chris Harmer says:
28 March 2013

For efficient power conversion and cool running, most electronics these days uses what is known as a switched made power supply instead of a simple transformer. These operate at much higher frequencies that the electricity mains, and can extend to the high frequencies that radios, TVs and remote controllers operate at. Radio amateurs operate very sensitive short wave radios and have had a lot of interference problems with compact fluorescents particularly the cheap ones where the switch mode power supply is not properly suppressed as required by EU legislation. But its not just bulbs – radio amateurs have had problems with the plug based power supplies for phones, etc, with phone chargers, supplies for broadband routers, and with solar panel installations. Often these are in houses down the street and the signal comes up the mains cable. Perhaps Which should be talking to the Radio Society of Great Britain on this as they have lots of experience but they do NOT take consumer complaints – take those to OFCOM.

Paul Lettington says:
28 March 2013

Yes, I bought 3x Homebase branded 204v GU10 LED bulbs to replace halogen spotlights. They broke any DAB radio within about 3 metres. I returned them and exchanged them for Philips MyVision ones and the problem went away.

Dave Smith says:
28 March 2013

Though the lamp’s power supply GENERATES the interference, it’s usually not the lamp itself that’s RADIATING the interference, but the wires supplying it. If the power was being delivered solely by a pair of parallel wires (like in cable), all would probably be okay. But lights tend to have one of the supply wires diverted down to a wall switch. This is the bit that tends to radiate the interference generated by the lamp.

I suspect that future wiring guidelines will require light switch wiring to be double pole (or at least have both supply conductors brought to the switch, so most interference will be cancelled.

Incidentally, I have seen inside lots of kit (PC power supplies, electronic lamp supplies, wall chargers, etc) to find vacant spaces on the printed circuit boards where suppression components SHOULD have been fitted (and presumeably were when being compliance tested). Of course, not having these components fitted doesn’t affect normal operation of the device, and saves the manufacturer pennies that accountants like to add up…

A Wilson says:
28 March 2013

We have had a similar experience. Since changing our kitchen lights to 12 Kosnic LED GU10 36 Warm White 5w bulbs in ceiling lights our Roberts digital radio on a shelf nearby keeps cutting out. The problem doesn’t immediately go on turning them off but has gone a while later, and if we start the day not using the LEDs the radio is fine

Alan says:
28 March 2013

I’ve experienced a similar problem, when using a 46w Osram Classic Eco Superstar Halogen light bulb, in a touch on/off (without an external physical switch) bedside lamp, my DAB hi-fi radio has stopped transmitting. I’ve also used the same light bulb in another bedside lamp with an external switch, but the DAB radio transmission has not been affected.

A J Herridge says:
28 March 2013

We have experienced 50Hz interefernce on our FM radio from a cluster of three LED lamps in the next room, about 3m away. The lamps are 3watt 220/240volt Warm White GU 10 manufactured by Eterna Cat No 36/10. The lamps were purchased from a local electrical shop here in Pontypridd South Wales. The lamps have been replaced with a different type of LED lamps and the problem has gone away.

Bob says:
29 March 2013

Just a note in reply to remote controls that stopped working…it should be remembered any device that uses a CPU can crash for a variety of reasons and the removal of the battery for a few seconds will enable the processor chip to reset. Problem solved.

I think it is worth reiterating that this problem is not confined to LED bulbs or DAB radio. The authorities are allowing all manner of non-compliant devices to be sold and used in the UK, thereby failing in their duty to protect our vital radio spectrum upon which we rely in so many ways. If this is allowed to go on unabated there is a serious risk of irrepairable damage to many different kinds of radio services, some of them involving safety of life. The authorities must be called to account over this before it is too late.

John Dalton says:
29 March 2013

Is there any mechanism available to force the authorities to police these standards? So often it happens that laws exist but the rich and powerful only apply those that suit them.

Officially I believe Trading Standards should, but this route is generally ineffective. I believe the best route is for accumulated complaints to be passed onto the industry trade associations – it is in their interests to protect their (reputable) members from sub-standard products. In this case it would be the LIA (Lighting Industry Association) in the UK, and CELMA (Federation of National Manufacturers Associations for Luminaires and Electrotechnical Components for Luminaires in the European Union) in Europe as a whole.

Although Trading Standards should deal with such problems they pass the buck to OFCOM, which then ignores it. While OFCOM is responsible for both regulatory matters and promotion of industry then there will be no resolution to these difficulties because much higher priority is given to the promotion of industry and regulation takes a back seat. The only solution, as I have mentioned before, is to take technical regulatory aspects away from OFCOM and set up a separate organisation to deal with both regulations and enforcement. While the present situation exists there will be no real improvement to the problems being experienced. As Richard pointed out, as I have in previous posts, the problems go way beyond the use of LED lighting. I guess that the problems caused by LEDs have brought the matter of E-M pollution to the notice of the general public whereas those of us involved in radio communications have been of how bad the situation has become for a very long time but have been but few voices in the wilderness. Hopefully the LED problem will make a lot more people aware of the situation.