Interference from Lighting Systems
Light Emitting Diode (LED)
LED lighting is set to revolutionise the way we light our homes, businesses, vehicles, trains, boats, aircraft, and more. The humble LED uses a fraction of the energy of incandescent lamps and offers thousands of hours of lifetime. Sadly, the control and power electronics are proving to be less than reliable, and when poorly designed, can generate a considerable amount of radio interference. This interference has been shown to wipe out Band II VHF Stereo and Band III DAB radio. As the safety-of-life aircraft band sits in the middle of those two, poorly designed LED lighting also posses a danger to aircraft communications, navigation beacons, and Instrument Landing Systems. Boat and car owners, who have retro-fitted LED lamps to existing lighting systems have also experienced interference from some types of lamps.
There are two known generators of interference: The first source is the switched-mode power-supply. Due to the size constraints, some manufacturers are missing out the necessary filter components (as detailed on the SMPS page) and this results in a great deal of conducted emissions.
The second source can come from a device known as a buck-driver - a type of switched-mode power-supply that regulates lower voltages (typically 12V) to provide a constant-current to the Light Emitting Diode. These devices typically operate with a switching-frequency of 5000 Hz, but they can produce harmonics (mixing of multiple frequencies) that extend up to 30MHz, and higher. Some are making it to 220MHz, where they cause serious degradation to any nearby DAB radios.
The following are known to be affected by LED lighting interference:
|Digital Audio Broadcast (DAB)||174 - 240 MHz|
|Marine VHF||156 - 162.025 MHz|
|Amateur Radio 2 metre band||144 - 146 MHz|
|Airband||118 - 136.975 MHz|
|FM Stereo broadcast||88 - 108 MHz|
|Baby monitors||49.30 - 49.89 MHz|
|High frequency services, inc. long range marine & airband, Shortwave broadcasts, Amateur radio allocations, Citizens' Band radio, plus wireless devices operating on 27MHz||3 - 30 MHz|
EMC industry investigates
The EMC industry has published concerns over the proliferation of LED lighting that fails to meet any standardised testing and the essential requirements of the EMC Directive. The European Union is also concerned and has published a Cross Border Surveillance Report on the issue. Publishing a report is only helpful if member state's Market Surveillance authorities are actually doing their job!
We are gratefully indebted to the EMC testing house METECC for sharing their finding after testing a large number of off-the-shelf LED lamps. Click the image below to read their findings:
Radio interference from LED lighting
Thilo Kootz DL9KCE, of German Amateur Radio group, Deutscher Amateur-Radio-Club (DARC), demonstrates their findings when they tested a range of LED lamps with a home-brew Line Impedance Stabilization Network (LISN) and a Software Defined Radio:
Public wants answers
Consumer organisation Which? recently asked readers to get in touch with their LED interference issues. They did not believe there was a problem. The comments speak for themselves!
We would urge caution if you are planning to purchase LED lighting solutions. Some of the well-known manufacturers are following the rules and producing EMC-compliant lamps. Unfortunately, the market is flooded with cheap, non-branded, LED lamps which do not comply with the essential requirements of the EMC Directive. If you watch the video above, you will see branded lamps can also fail EMC testing.
Your safety may also be at risk. This video demonstrates the dangers of some LED lights that ignore all of the mains-safety rules:
We were made aware of this question on a sailing forum:
Question re: LED Interference with VHF
"I recently installed an LED tri-color and an LED anchor light. Unfortunately, now whenever I have either light on I only hear static on all stations on my [marine] VHF, no matter what I do with the squelch. It's no good because it's important that I have the tri-color and the VHF working properly at the same time for night sailing. Any suggestions as to what is causing this?"
As demonstrated in the test results of the METECC LED Investigation, Marine VHF is also susceptible to interference from non-EMC-compliant buck-driven LED lamps. Some forum posters have suggested new marine VHF radios are more sensitive that older models, and are thus more likely to pick up the interference from the LED lamps. This is nonsense! There have also been suggestions regarding the installation of ferrite suppression rings. If the buck-driver is not compliant, you will be wasting your time. The best solution is to fit EMC-compliant LED solutions. If you wish to retro-fit LEDs to existing lamps, ensure they are resistor-limited, as these will not cause interference to your radios.
Compact Fluorescent Lamps (CFL)
Ageing compact fluorescent lamps can suffer from component failure in their electronic ballast resulting in a sudden increase in radio interference. The electronic ballast is similar to a switched-mode power-supply and it can generate the same sorts of interference as detailed on our SMPS page.
Although not an interference problem, it has also been reported that CFLs can be seen to "flash" in the night. This was believed to be caused by leakage in the light switch allowing a charge to accumulate in the power-supply, which is then discharged through the mercury vapour gas in the tube, causing a flash of light. Another issue can be the generation of infrared pulses which interfere with the operation of remote controls for televisions, DVD players, etc.
It has been reported to the UKQRM Yahoo group that some suppliers in North and South America have been supplying electronic ballasts for domestic installation that only meet the FCC Part 15 Class A requirements. Equivalent to EN55015 Part A, this type of lighting is for industrial use only and should not be installed in a domestic environment, as it is likely to cause radio interference. We have not received any messages suggesting this practice occurs in the UK or the EU ... yet! If you are planning to purchase luminaries for domestic use that use electronic ballasts, they should meet EN55015 Class B limits for conducted and radiated emissions. We would like to urge installers to use Class B equipment everywhere, so as not to create radio no-go zones on business parks and industrial estates. The local power-grid will also thank you for not overloading it with harmonic junk!
Page updated: 9th May 2017