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LED lamps interfering with radio transmissions

LED lamps interfering with radio transmissions

After hearing various complaints from their readers about LED light bulbs interfering with radio transmissions, Which? Conversation, an online magazine examining today’s consumer issues, decided to conduct their own tests. They found that when they powered on “cheap, generic 12V LED bulbs” located within a “few meters” of a digital radio, the radio signal went fuzzy. Placed within a few centimeters, the signal cut out all together.

While their preliminary test concluded the issue is limited to “cheap knock-offs rather than branded goods”, it is important to identify the reason LED lamps are causing interference. To simply identify the price of a bulb as the culprit is both unsatisfactory and careless. The average consumer targeted by Which? Conversation cannot reasonably assess production and design value of LED lamps. In fact, those types of simple declarative statements (“The energy-saving LED bulb that switched off the radio”) that fail to provide any concrete answers can tarnish the LED lighting industry and impede the widespread adoption of LEDs. Not good.

As such, we thought we’d offer an explanation from an engineering perspective.

Electro Magnetic Interference, or EMI, can be a big problem and is largely due to the fact that the LED power supply is switching at some rate to turn the supplied AC voltage into a DC voltage. Achieving this results in a circuit with lots of inductance, which produces an electric field around the circuit. In many cases the body of the lamp is plastic, which does not block transmission of the field. As a result, the field can interfere with electrical products around them.

In a good power supply design, the large current-carrying inductors are individually shielded to constrain this field and the power supply itself may well be electrically shielded by, for example, a metal encasing. Leapfrog Lighting lamps hold patents related to the power supply design, which includes a method to prevent EMI.

The reason “cheaper” LEDs are causing interference is a direct result of design choices. All methods used to prevent EMI—such as shielding or noise suppression components and circuits —require additional R&D and material costs. In a highly competitive LED lamp market, some manufacturers cut production costs so they can lower the price of their product and appear more attractive to the average buyer. When energy efficiency seems to be the main driver for many LED manufacturers, features such as EMI prevention (not to mention light quality and color consistency), get scant attention.

Since consumers can’t exactly dissemble a lamp to inspect a manufacturer’s design, how can they ensure a LED lamp won’t cause EMI?

The fact is, any piece of electrical equipment that is sold in the US is required to be compliant with Federal Communications Commission (FCC) CFR 47. Look for a stamp on the lamp that indicates the product is verified for EMI under FCC testing. All Leapfrog Lighting LED lamps have been tested to EMI standard and are FCC certified.

Leapfrog Lighting PAR30 lamp with FCC mark

FCC certified Leapfrog Lighting PAR30 lamp

If an LED lamp sold within the US is interfering with your radio (or TV) signal, report it to the FCC immediately.


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4 Responses to LED lamps interfering with radio transmissions

  1. Installed 7 LED lights kitchen ceiling spot lights GU10. Massive interference with AM Radio. Very painful experience. It would be interesting to have a comparison for different manufacturers.

  2. Installed the ecosmart LED bulbs (from homedepot) in my garage.
    I first tried it on the Garage door opener itself – and the remote just would not work. I then installed it on a separate fixture (1 ft from the garage door opener). The remote would work sporadically. Sometimes, it would work right away. But other times, it wouldn’t work when trying to open the garage door from outside. (no FCC mark on the bulb)

  3. I wish I could had found this out sooner, as I started upgrading to LED. I spend a lot of money on bulbs of different shapes, watts, etc. on drivers, and ceiling fan circline light conversions. the bad days and frustration from trying to find out or figure out why my Bose is getting interference. so far the ones I checked for the FCC mark, none had it, I have a bunch more I need to check, I’m pretty sure they won’t have it as all these china, hong kong, etc, from different sellers on Ebay. Can this also happen to my computer? there are times here this annoying sound of interference but not bad as the radio, one station at first, as it increased to 2,3,4 stations, i guess from the conversion. I’m so upset right now, how do I report this, so many seller’s. I have items bought for DIY project and waiting some that haven’t arrived.