mouser.com/te 15
Communications Commission (FCC) specification
using ferrite beads and various shielding techniques.
This technique is enough to satisfy FCC specification
part 15, which is sufficient for laboratory conditions
but is inadequate for the application of Street
Lighting.
This was precisely the case when the city of
Amarillo, Texas, United States, piloted the
installation of a set of LED streetlights. A
"concerned citizen" reported significant AM
radio interference after the LED lights had gotten
installed. After an exhaustive analysis, it was
determined that the luminaire was the source of the
problem. A small amount of RF noise can couple
onto the power or ground line, serving as a radiating
antenna (Figure 1). The length of the power line
coupling the noise controls which frequencies
radiate well. Since there are many different line
FIGURE 1: Typical wiring connections for an LED streetlight.
(Source: TE Connectivity)
Light-Emitting Diode (LED) lighting does
not generate EMI. The EMI gets generated by
the electronic drivers that are powering the
LED. The adoption of these drivers replaces the
electromagnetic ballasts, which operate at a much
lower frequency (60Hz). Electronic drivers operate
at 20–60kHz, which is between 50–200 times the
frequency of a magnetic ballast, producing much
higher levels of EMI due to the high-speed switching.
The tradeoff is that the higher frequency drivers are
much smaller, lighter, quieter, and more efficient.
The good news is that EMI is not a recent
phenomenon, and there are a large variety of
existing solutions out in the market today.
Unfortunately, there is very little regulation
concerning EMI in the lighting industry. As a result,
lighting manufacturers are designing to the Federal
