The Department of Ecology, Sustainable Development and Energy, has published in date of 4 August a boating safety alert about LEDs bulbs (¹). The text warns boaters on the risks of radio interference found where the VHF antennas are close to navigation lights or bridge lamps equipped with LEDs bulbs.
Indeed, some LEDs (Light-Emitting Diode) can cause electromagnetic interference disrupting radio frequencies as the VHF transmissions, causing losses in the AIS data transmission, and also that of the GPS data by VHF transmitters with Digital Selective Call in the event of a distress signal. These interferences are generally due to bad bulbs power supply and shield design
Electromagnetic interference, or EMI (Electro Magnetic Interference), is largely due to the fact that LEDs supply regulates the voltage of the battery (10v to 14v) via a convertisseur continu / continu. This energy conversion is done through a high frequency "cutout" characterized by a high efficiency but which can generate electromagnetic interference on the frequency used by our VHF and AIS transmitters
The result is a circuit with lots of inductance that produces an electric field around the circuit. In most cases, the body of the lamp is made of plastic, that does not block the emission of the field. Accordingly, the field can interfere with electrical devices which surround it. In a good design of the power supply, current drivers are individually shielded to constrain the field, the power supply itself must be electrically isolated by a metal shield.
In principle, The CE marking is required on the LEDs. It shall presume electrical and photobiological lamp safety, as well as their electromagnetic compatibility (CEM ²). Bulbs marked CE-2014/30/EU should not present risk of electromagnetic interference. However the EC standard requires that a declaration of conformity on the honour on the part of the manufacturer or the importer who remain solely responsible for the drafting of technical documentation and control procedures (³).
It is up to boaters to check compliance with one of these standards on purchased lamps, and return to distributors those would not be compliant with.
(²) Directive 2014/30/EU of 26 rd 2014
(³) In the United States, any piece of electrical equipment that is sold there shall be submitted to the Federal Communications Commission (FCC) CFR47 which tests and verify conformity.