FCC Part 15 and US EMC Compliance: A Different Road from CE

European lighting products are marked CE, with EMC compliance demonstrated to EN 55015 and EN 61547. North American products carry a different set of marks and follow a different regulatory path, and for LED drivers the relevant US requirement is FCC Part 15 — the Federal Communications Commission's rules for radio frequency devices. The two systems look similar from a distance — both limit electromagnetic emissions — but they differ in legal structure, in the classification of the product, and in who bears responsibility for compliance. For a manufacturer shipping drivers to both markets, the differences matter in cost, in documentation, and in legal exposure.

FCC Part 15 (47 CFR Part 15) covers radio frequency devices, and it divides them into two categories. Intentional radiators (Part 15 Subpart C) are devices that intentionally generate and radiate RF energy — Wi-Fi transmitters, Bluetooth modules, remote controls. Unintentional radiators (Part 15 Subpart B) are devices that generate RF energy incidentally as part of their operation — computers, power supplies, and, critically, LED drivers. A switching power supply operates at frequencies from tens of kilohertz to several megahertz, and its switching edges generate RF emissions in the 150kHz to 30MHz conducted range and above 30MHz radiated. That makes the driver an unintentional radiator, subject to Subpart B.

Subpart B sets two classes of limits. Class A applies to equipment intended for commercial and industrial environments, where the limits are more lenient. Class B applies to equipment intended for residential use, where the limits are stricter — the reasoning being that a device in a home shares the environment with radios and televisions and must not interfere with them. The conducted limits for a Class B device, measured with a 50µH/50-ohm line impedance stabilization network (LISN), are 66 to 56 dBµV quasi-peak from 150kHz to 500kHz (decreasing with frequency), 56 dBµV from 500kHz to 5MHz, and 60 dBµV from 5MHz to 30MHz, with corresponding average limits 10 dB lower. The radiated limits for Class B, measured at 3 meters, are 40 dBµV/m from 30 to 88MHz, 43.5 dBµV/m from 88 to 216MHz, 46 dBµV/m from 216 to 960MHz, and 54 dBµV/m above 960MHz. These are the numbers a driver design must meet.

The compliance path differs from CE. In Europe, the manufacturer performs an assessment and signs a declaration of conformity — a self-declaration model. In the US, most unintentional radiators follow the Supplier's Declaration of Conformity (SDoC) route: the responsible party (the manufacturer or importer) ensures the product is tested to the limits by an accredited test lab, and keeps the test report and compliance information on file. The product carries the FCC logo, and the responsible party's name and address must be on the device or in the user documentation. Some devices require certification (the more formal route with an FCC-recognized TCB), but LED drivers are normally within the SDoC scope. The key legal point is that the responsible party is on the hook — if the product is later found to exceed the limits, the FCC can require corrective action, and the responsible party bears the cost.

One nuance worth knowing: lighting products with switching power supplies have historically been evaluated under both Part 15 (for the digital/switching circuitry) and, for fluorescent and some other lighting, Part 18 (for RF lighting devices). LED drivers are treated as Part 15 unintentional radiators, and the tests are conducted according to the ANSI C63.4 measurement procedures, which are the US equivalents of the CISPR test methods. The practical difference from EN 55015 is in the details — the LISN design, the measurement distance, the frequency tables — rather than in fundamental philosophy. A driver that passes one set of limits will usually come close to passing the other, but not always, and the test must be repeated under the US procedures with a US-based or US-accredited lab.

For a buyer, the practical points are these. Confirm that the driver carries FCC compliance documentation and identify the responsible party. Check whether the compliance is Class A or Class B — a Class B device is acceptable in both residential and commercial settings, while a Class A device is restricted to commercial/industrial use. And be aware that FCC compliance is a legal requirement for selling into the US market, not a voluntary certification — the absence of FCC compliance documentation is a real regulatory risk, and the importer of record shares it with the manufacturer. In North America, EMC compliance is not a CE-style self-declaration that can be handled casually; it is a legal obligation with named parties and test records behind it.