/ 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.


I have a 2014 Prius C that uses standard halogen bulbs for the headlights. About two years ago I upgraded to a set of LED low beam bulbs. They were 4-Phillips-Luxeon 45 WT 4,500 Lumen bulbs that were powered by the standard H11 12V connector. There was no additional power supply between the LED bulb and the 12V connector.

When I installed the LED bulbs, I noticed that when I turned on the LED headlights I Lost several FM radio stations that I like to listen to. Turned the lights off, and the radio stations were back on. This is the standard FM HD radio that comes with the Toyota Prius C with the standard stubby radio antenna on the rear of the roof. OK, I started listening to a collection of music on the USB port, so no big problem.

Yesterday, my driver’s side LED burned out. Now I have choice of selecting a new set of LED bulbs. I noticed there are some LED bulbs that have power supplies between the 12V H11 connector and the LED bulb. Does anyone have any suggestions for my new LED bulb purchase that might return my distant FM stations when the headlights are on. Thank you.

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Duncan – I expect that the power supply used with some LED bulbs is there it stabilise the voltage to maintain constant brightness and possibly to prolong the life of the lamps. When the battery is being charged the voltage can rise to approaching 15 volts.

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I take your point about surge (voltage spike) protectors but I was referring to voltage stabilisation. I have no idea of the costs involved. I agree with your suggestion about screening wiring.

Prius owner has mentioned obtaining new LED lamps. My suggestion would be to explain to the supplier that the lamps must not cause interference. If there is any problem then it should be easy to get a refund.

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Bought “Lumilife” LED direct replacement bulbs for 50W halogen GU 5.3. Worked with existing 12v AC supply and light output good. Did not notice problem until darker mornings when lights in bathroom on at same time as morning radio alarm. Then FM radio signal completely drowned out by “white noise” interference.
Tried adding Ferric Chokes to lamp LV supply but no improvement. Did notice that Philips bulbs with higher light output did not affect radio. Spoke to supplier who said this ws normal fo LED bulbs and nothing could be done except moving radio further away. (Not possible because already on opposite side of bedroom from bathroom.) Tried experimenting with aluminium foil shielding around base of bulb where rectifier situated but no difference.
Then moved aerial for radio and suddenly no interference.
So if you have issues with LED bulbs affecting FM radio try moving/adjusting the aerial or even rotating the radio.

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Old Fogie – I have been looking at the problem of radio interference by LED lighting for a few years now, and have now met people who have experienced problems, as well as reading about them on this and other websites. Problems seem to be more common with the 12V MR16/GU 5.3 lamps and could originate in the lamp or the driver, with the interconnecting wire effectively acting as an aerial for transmission of radio interference. Some have used ferrite products or screening (as Duncan mentions). It’s a good idea to move the radio or aerial, as you have suggested.

I suggest asking the retailer to replace the problem lamps or provide a refund. If enough people do this and give negative reviews then they might change their supplier.

Another approach would be to switch to mains voltage LEDs such as GU10s. These obviously don’t need drivers and I’ve seen fewer complaints about radio interference.

Mike Fulton says:
30 October 2017

I have recently (October 2017) installed a 13-watt Philips LED bulb in a bedside lamp, the bulb being at approximately 110 mm from the antenna of my FM radio. When the bulb is switched on, there is continuous interference, but not such as to completely blot-out reception of the station concerned (usually Radio 4).

I expect that if you move the radio away from the lamp, the interference will disappear. Light dimmers, microwave ovens and routers can also create problems at very close range and it will be more of a problem if you have a weak radio signal. It can be explained by the inverse square law. You might find that other LED bulbs work fine next to a radio but it’s best to keep them apart.

Same here but with one of those unbranded “classic” looking led bulbs in my bedside light.

Debra Saunders says:
18 November 2017

We just installed in the kitchen a 32 watt led ceiling light r-sunrise £16.49 from Amazon, now I have almost no reception in my fm rafio

I bought energy efficient led bulbs for my bedside lamps from Sainsbury’s. Since fittin them my dab radio only works when the bedside lamp is off. Do I have a right to return them?

There is no harm in trying, Jo. Before you do, it’s worth checking if moving the radio away helps – for example to the other side of the bed.

We have A neighbour who has recently installed a rectangular floodlight in his back yard which is motion sensitive and has a dawn-to-dusk sensor. When the light is activated our FM reception is destroyed and a replaced with a very loud spitting/buzzing distortion for the two minutes that the light is active. The light is 8 METRES from the antenna which is an extended loop wire which gives a good stereo signal; the distortion is as bad when the radio is switched to mono.

This light has an internal power supply and probably a non-replaceable bulb unit. OFCOM (via the BBC) are being polled for action but it is not easy to get them out of their comfortable seats…

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I would suggest having a word with your neighbour, who may be able to reject the floodlight as unsatisfactory. If they have paid to have it fitted, they might be less helpful. I once reported a radio interference problem caused by neighbours and it was dealt with promptly, but that must have been 35 years ago.

I would be very interested to know the outcome.

There is a legal remedy but I suggest you do what Wavechange has suggested in the first place. Your neighbours might not have been aware of the interference their floodlight has caused. You don’t have to put up with it or go to significant expense to curtail it so it might be helpful to have that knowledge up your sleeve when you talk to your neighbour.

Martin McIntosh says:
7 December 2017

Our DAB radio in the kitchen on the other side of the house cuts out completely as soon as we switch on the LED spotlights about 15 metres away on the landing or in the upstairs bathroom. The same thing happens with a different make of DAB radio in the bedroom. I replaced 50 watt 12v Hologen MR16 ceiling spotlights in our upstairs bathroom and landing with AuraLED AL-MR16PRO-7W bulbs, recommended by a local retailer. They were the only ones I could find that worked with the existing 12v transformers without flickering or strobing. Lumilife MR16 spots from LED Hut do not interfere with the radio signals but flicker all the time. Unfortunately I had been using the Auraled lights for some months before we bought the DAB radios and realised there was a problem.

richard hart says:
8 December 2017

In reply mainly to Mike Fulton, I believed I had exactly his problem. After several cheapo LED bulbs, I put a Phillips 13W LED replacement where I used to have a standard BC 100w, in my bedside lamp. The lamp is on a 4ft chest, and 4ft from my old Sharp radio that is usually tuned to R4FM. Immediate low volume pink noise over the audio as soon as the light is switched on. The previous LED bulbs were worse.

So I thought of moving the room around. After a hour or so of preparation I was ready to test, moving the radio further from the bulb. As soon as I started to move the radio, reception became clear. Reception remained clear when the radio was on the chest 1ft from the lamp. After some fiddling, I am satisfied that the interference is coming from the proximity of the radio and the lamp mains leads. They both plug into a block below my bedside table, and how the cables cross each other as they leave the block seems to be critical.

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That’s unfortunate but interesting, Richard. It suggests that the interference is not being picked up by the radio aerial but via the mains cable and that the interference is also being transmitted from the lamp via its cable. Lamp dimmers can produce interference in the same way.

You might find it helps to extend the radio aerial. If you are game for more experiments you could try a different radio because they do vary in their ability to pick up interference. A battery-operated radio might not have a problem, but obviously would be expensive to operate.

Duncan – Richard says he is listening to Radio 4 FM and I guess he will have a telescopic aerial or simply a bit of wire on some bedside radios. I don’t think ferrite aerials are normally used for FM, but could be wrong. My old Hacker Hunter radio had great reception and sound quality but probably had poor screening because it picked up interference that caused no problem with cheaper radios. 🙁

David James says:
25 December 2017

Don’t know about dab, but these bulbs affect my hearing aids quite badly. This needs to be sorted and quickly.

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A very interesting piece of information.

My DAB car radio suffers from this problem, I sometimes sit in the car to listen to football matches as it’s the only DAB radio I have. For evening matches I often trigger the LED floodlight on the drive, the radio is barely audible until the timer runs out and the flood light turns itself off, then the reception is crystal clear again (I think I need to buy a portable radio).

I have a cheap LED floodlight that I bought from Lidl to use as a worklight and that’s fine. Some manufacturers manage to comply with the regulations but others don’t seem to. I now know several people who have had problems but I have been lucky and have tested every bulb that has come into the house. It must be a real pain to put up a floodlight and find out that it wipes out radio reception.

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Can you help me with a part number, Duncan? I’ve not had problems with DAB interference, just one bulb that affected an FM radio, though do know people who have had problems. I have tried to get hold of problem bulbs but these have just been disposed of and replaced by others. At least this demonstrates that there is an easy solution.

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Ah well. Life moves on. The only Maplin kit I ever bought was a clock timer, back in the mid-70s. It turns my router off at night and on in the morning. Oops – we are off-topic.

Gary Williams says:
7 February 2018

I have a number of unbranded GU10 240V LED bulbs in our kitchen area. Nearly every time we switch them on our router resets, leaving us without an internet connection for 5 minutes or so while it goes through its reset sequence. I have not experienced this problem with any other LED bulb that we have. The bulbs causing the issued are located approximately 5m from the router.

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I agree with Duncan about switching bulbs, but I would also contact the seller and ask for a refund. If the manufacturer has not complied with the regulations on RF emission they might not have bothered about safety requirements either. There are many unbranded electrical products that are unsafe.

Led among other electronics make trouble for Ham operations as well. Interference so we cant use our radios. Plasma TV is the worst

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Paul says:
30 March 2018

I’m having that problem now. I bought my bulbs at protuninglab, an online store. These are the fog lights and they are causing radio interference. I put some ferrite chokes on them today and the situation has improved a bit but still remains as a problem. I’m not sure what to do at this juncture.


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Paul – I suggest that you contact the supplier and try to get a refund. It might be best to stick with whatever lamps the manufacturer recommends.

Rob Harrison says:
26 April 2018

In a recent European wide test of LED floodlights by two independent working groups, the results were extremely poor. The testing consisted of safety tests and meeting EU interference standards both by technical testing (meeting EU standards) and administratively.

Reference document here http://www.tukes.fi/Tiedostot/sahko_ja_hissit/JA2015-EMCLVD_Results_of_Campaign.pdf

Out of 87 safety tested only 9 met all safety standards and 76% were considered dangerous , posing a shock risk. For EMC testing only 47% met current standards up to 30MHZ and 55% were OK from 30-300MHz. For combined safety and emc/admin’ testing only 5 lights passed both tests.

This is a damning indictment of the way consumerism has degraded the quality of products in general and of government(s) not properly funding the relevant standards authorities to keep poor product from the market.

Solar panel RFI, plasma TV, and PLT(data over the mains) are to other major contributors to EMC pollution. Ofcom do not want to know and have changed their interpretation of what is considered harmful so as to allow their very limited resources to deal with only “danger to life” situations. They take reports of local interference, but very rarely act. Last April new legislation was enacted to specifically address these problems. However, Ofcom don’t seem to want to use these powers.

This is just scratching the surface of the problem of non-compliant product swamping the marketplace in all areas, not just electronics.

Angry Ham,


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I changed out five 12V 50W MR16 halogen downlighters for 12V 5W MR16 LED downlighters. Interference swamped my and my neighbour’s FM and DAB. The 12V individual power supply units were rated for a minimum load of 20W so they didn’t match the 5W LEDs. I changed the lot out for 240V GU10 LEDs, a mix of Integral and Aurora. The interference ceased, except for a whisper when a radio was held up against the bulb.
It does not appear to be common knowledge that you should not replace 12V halogens directly with 12V LEDs. Not only does it cause interference but carries a risk due to the power supply driving an incorrect load. Perhaps LED manufacturers should have a warning on the packet.

The MR16 halogen downlighters in my bathrooms were on individual power supplies and I wondered if these drivers would work satisfactorily with MR16 – LED replacements, expecting to have to remove the drivers and rewire the fixtures to accept GU10 LEDs, as you have done. I tried one and the only interference I could detect was when an FM radio tuned to a weak station was close to the lamp, and there was no DAB interference. I then replaced all the halogen lamps with MR16-LEDs and they are fine. I was lucky but agree that manufacturers should put a warning on the packet.

Dimmers installed for incandescent lighting might not work properly with LED lamps and might cause damage to them. Why isn’t this mentioned on the packet?

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MR16 LEDs operate on a nominal voltage of 12V. Specifications often don’t give a range of acceptable voltages or even state AC or DC, which is not very helpful. I’ve fitted 12V LEDs in off-grid applications where the lamps are powered by 12V lead-acid batteries. Here the voltage can reach 14.5V when the batteries are being charged. The better 12V LEDs sold for this sort of use will run on 10-30V DC and are protected from spikes produced by the alternator in the generator. I doubt that the ones sold for household use will accept this voltage range but if it was critical I suspect the specifications would make this clear. The drivers I have seen were AC output and will work on DC, so presumable there is a bridge rectifier on the input.

I am well aware that an individual LED must operate at a controlled current but the SMPS that drives one or more LEDs ensures that this happens despite variations in the input voltage.

duncan, that is correct. The current needs to be controlled. However, power supplies are of two types, constant voltage and constant current depending upon whether the LED has current control on board. As I understand it.

Oops, my post should read: ‘The drivers I have seen were AC output but the LED lamps will also work on DC, so presumable there is a bridge rectifier on the input.’

Malcolm – MR16 lamps – which is what we are discussing here – all use drivers that provide approximately 12V. Yes there are other types of LED lamps that use constant current drivers.

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I replaced six 120 Watt Par38 lamps in the kitchen of my recently acquired house. The first attempt was a set of fluorescent based PAR38 format lamps (remember I have big holes in my ceiling and that limits the choice) but they took too long to come up to full power. Next I tried a set of LED based PAR38s from TLC (Southern) Ltd and they were quite good except for their short life before one or more lost elements. Some cheap Chinese equivalents came next and they were good but too cold in colour temperature and were consigned to my garage. None of these threw up any serious EMI problems. Eventually I bought a set of LED round panels that fitted into the ceiling holes perfectly. They are edge illuminated panels with 12Vdc LED lamps that give an even disc of light and each consume (claimed) 12W. That is when the trouble started with FM stereo reception picking up an all-encompassing white noise interference. I tried complaining to the supplier as they fittings carry a CE mark and he told the Chinese makers that they could not have gained a CE logo while pumping out so much EMI. They went through the motions of sending me a new set FOC but these were just as bad. To be pragmatic, I simply switch my radio to mono and carry on and unless BBC Radio 4 is down on power the reduced hiss without the stereo decoder in operation is acceptable for the excellent quality of light I have at a mere 72 Watts versus the 720 Watts of the old incandescent PAR38s.
I am pretty sure it is the switch mode power supply causing the EMI but I haven’t done any trials with known ‘silent’ PSUs.

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One of the units failed this week and I tested it with a known good power unit. The illuminator (for the want of a better term) is okay so the SWPS is responsible. Opening it up reveals an 8 pin DIL IC, a few surface mount components, a small transformer or inductor, and two Al. caps. In my recent experience cheap Chinese Al. caps. have a limited life so they would be my first port of call to replace. I was Technical and Marketing Director for a manufacturer of security equipment for ten years and never experienced an aluminium capacitor failure except when cross-polarised. As you will know, there’s no doubt about that sort of failure! The light source is a good product but it is spoiled by a poor quality power supply with no attention to EMI suppression.
Here’s my ad hoc EMI test https://www.youtube.com/watch?v=31XuC1hds2w

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You flatter me Duncan, I am not really that knowledgeable. My training was in polymer technology and engineering many years ago and what knowledge I have of matters electrical/electronic have been acquired as an enthusiastic amateur over several decades. It started with being impecunious but keen on having decent music reproduction equipment. Rather than buy one of the frankly poor new-fangled cassette decks, I bought a Heathkit open reel tape recorder kit and building that and ironing out the inevitable snags piqued my interest in electronics. Moving on a couple of decades I was left standing when all others had sat down when the small company I worked for bought the rights to a novel design of Doppler microwave device. That was a steep learning curve I can assure you! Because I was the only senior member of staff with any electronics knowledge at all it fell to me to milk the boffin who designed it of all the information I could. A modicum of intelligence and the motivation to survive in the job spurred me on to do my homework avidly! Ironically the inventor of this device was also unqualified having learned all he knew by experiment and being a radar tech in the RAF. Life deals a hand and it behoves us to play the cards to the best of our abilities and not to be narrow minded and inflexible. I shall now release the thread from this hijack! Oh, and yes you’re right about Chinese manufacturers. I spent a few days with a Taiwanese manufacturer who was making one of the early PIR flood light controls for us in the 1980s. I was horrified to see the total lack of safety concerns in the disparate little sub-contractors’ units. Mothers soldering up boards with their babies asleep under the bench for example. It’s better now, I’m sure and far more automated, but the working conditions will not be too different.

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can led street lights interfere with mobile phone signals

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The distance is going to be a major factor and anyone that if a streetlamp is very close to the house, interference is most likely. Interference can also be carried in the mains electricity supply to a home, particularly if the streetlight is on the same phase (there are three) as the house. The easiest way to find out if there might be a problem is to see if there is a decrease in signal strength when nearby lights come on, but bear in mind that signal strength can vary under different weather conditions.

If there is evidence of a problem then the local council should investigate, but it would be best to find out if others are suffering the same problem when the lights come on.

If it’s dark enough for the street lights to come on you probably need to stand underneath one to see what you’re doing, although the modern LED ones do seem to give a clearer and better light spread than the old sodium ones. Our cul-de-sac with about 30 houses has just three street lights and it seems to be well enough illuminated until midnight when they go to sleep for a few hours.

We seem to have discussed the possible effects of the power supply and circuitry of the street lighting rather than any interference effect from the LED lamp in the lantern itself – which is what I assumed Joan was asking about. I have no knowledge of the latter but the main advantage of using LED’s is the much lower power consumption so there will be a much lower current in the power supply running up the column than with previous types of street lighting. I don’t know whether the control gear at the base of a street lighting column generates any stray currents or electro-magnetic interference but again I would think a lower power demand through using LED lamps would be likely to have a moderating effect.

Kerbside power stanchions for electric vehicle charging might introduce a new source of interference and the electrical current could be considerable depending on how many feeds are provided.

A lot depends on the design of LED streetlights. When LED lights were fitted in our street a year or two ago the spread of light was very poor and I could no longer see to find the right key for the door, but it is much brighter below the lamps. Elsewhere the move to LED streetlights seems to have been an improvement.

Hopefully street lighting will be made to better standards than some of dubious products that are sold to the public but electronic drivers used for LED lighting certainly has potential to cause interference.

“Why have I lost DAB radio stations?” is the query in January’s print edition p39 (sorry can’t find it online).
WiFi is suggested as likely – but the author doesn’t address all the other RFI causes esp. from LED lights that are discussed here. And he speculates about new factors that are not reported by the OP e.g. that broadcast coverage has changed, or the building has become steel-framed!
I now feel more expert in all this than the Which “tech expert” – so thank you all.

With regard to LED street lamps, unless they work on a fundamentally different principle from ‘normal’ LEDs, the lamps themselves are likely to be running on a DC supply derived from a power supply located within the stanchion and supplied, in its turn, from the 230Vac public supply. It is the means of converting 230 volts of alternating current into x volts of direct current that could well be implicated in any electromagnetic interference (EMI) problems. Domestic LEDs use switched mode supplies and there is often a poorly designed (i.e.cheap) level of electrical ‘noise’ suppression. An old fashioned transformer and voltage regulator type is only likely to produce low frequency emissions (50Hz) from the transformer and not very strong ones at that. However these power supplies are expensive, bulky, and relatively inefficient compared with switched mode supplies and are, therefore, not the first choice. My knowledge of the workings of switched mode supplies is sketchy but I built one for operating my car headlights in a dim-dip mode (1/10 normal power) as legally required on new vehicles for a short period in the 1980s by construction and use laws until the EU over-rode them. This was a square wave oscillator with a suitable mark-space ratio to switch a power transistor on and off rapidly make the filament lamp appear to be smoothly dimmed but to dissipate as little energy as heat as possible. Regrettably its use rendered AM radio unusable due to raucous noise on the car’s electrical system. I gave up at this point! I believe that modern switched mode supplies use fundamentally this rapid on/off running and that the noise generated has to be suppressed in order to meet CE certification. Sadly CE logo stamps are ten-a-penny in the Orient! Take an AM medium or long wave portable radio tuned away from any stations or tuned to a distant one, and move towards the illuminated street lamp and see whether the interference can be heard to increase with your approach. If so, that points a finger at the lamp post.

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We had trouble with the reception from our kitchen DAB radio in the summer; it was around 10 years old and we thought it was the radio and replaced it; about 3 days later we noticed that the reception from the new one developed exactly the same problem when the kitchen lights were turned on. Replacing the LED lights (x9) with halogen spots solved the problem but now I find that halogen lights are being phased out! Are there any LED brands that do not do this? In the meantime have stockpiled some halogen bulbs……

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Thanks Duncan. Some devices such as Christmas lights have simple circuits including a capacitor, bridge rectifier and a couple of resistors, as shown in one of your linked articles, and there is no chance of radio interference. I believe that LED lighting generally uses high frequency drivers that pulse-feed the LEDs to achieve higher efficiency, albeit with the risk of radio interference unless this is suppressed. I’ve bought at least six brands of LED lamps and only one produced interference and even then only when the lamp was close to the radio. Maybe I was lucky but I did avoid buying cheap lamps online.

I suggest that Nick experiments with different LEDs bought locally and takes them back for a refund if there is a problem.