What is the FCC CFR 47 Part 15 Subpart B Test?

FCC CFR 47 Part 15 Subpart B Overview

FCC CFR 47 Part 15 Subpart Bis an electromagnetic compatibility (EMC) standard established by the Federal Communications Commission (FCC)of the United States. This EMC standard covers "unintentional radiators", such as electronic devices that unknowingly emit radio frequency energy during operation — for example, switching power supplies or clock signals — which may interfere with radio communications (e.g., broadcasting or mobile networks). Emissions should be managed so as to not cause interference for communication channels.

> Note:Unlike intentional radiators (such as Wi-Fi and Bluetooth modules, which are covered under Part 15E), passive interference generators (such as Wi-Fi and Bluetooth modules) fall under Part 15Bregulations.

Which Products Require FCC CFR 47 Part 15 Subpart B Testing?

Electronic products that have the potential for creating radio frequency interference fall under this testing requirement. Examples include:

1. Wireless peripheralssuch as mice and keyboards with Bluetooth technology (2.4GHz/Bluetooth).

2. Home control deviceslike temperature/humidity sensors and smart plugs equipped with low-power wireless modules (LWWMs).

3. Consumer electronicslike non-cellular cordless phones and Bluetooth speakers.

4. Industrial/appliance products: Small inverters, LED drivers, and USB chargers of 5W or above for industrial/appliance use, or small USB power banks with larger capacity.

5. Office equipment: Wireless printers/scanners that do not utilize dedicated communication channels, essential in office settings.

FCC CFR 47 Part 15 Subpart B Testing Items

Testing Scope:

Devices are tested for interference emitted via radiatedand conducted emissions.

1. Radiated Emission (RE)

1. Goal:Evaluate whether the electronic device emits excessive RF energy into its surrounding space during operation.

2. Method:The device is placed in a 3-meter semi-anechoic chamberand monitored using a spectrum analyzerfrom 30 MHz to 1 GHz(or up to 6 GHz for high-frequency devices).

3. Limit:Typical 3-meter emissions should not exceed -41.25 dBmto remain below threshold levels and avoid interference with other RF equipment.

2. Conducted Emission (CE)

1. Goal:Determine if a device transmits excessive RF noise back into the power grid via its power lines.

2. Method:The power line is connected through a Line Impedance Stabilization Network (LISN). A spectrum analyzermeasures interference between 150 kHz to 30 MHz.

3. Limit:Must meet CISPR 25 Class 5; quasi-peak values should not exceed 56 dBµV/m, ensuring the power network remains clean.

JJR Laboratory of China Offers an Easy Certification Process

JJR Laboratory(A2LA-accredited and FCC-recognized) offers Part 15B testing, formal reports, and assistance in obtaining fcc ids to access U.S. markets.

Certification Workflow

1. Pre-Assessment:

Submit product specifications (schematics, BOM, wireless parameters, etc.) to evaluate if the product falls under Part 15B (excluding high-power or intentional radiators).

2. Sample Preparation:

Deliver 2–3 completed units, including power adapters and technical documents (e.g., user manual, photographs showing key circuits).

3. Laboratory Testing:

radiated emission testing: Conducted in a 3-meter semi-anechoic chamberwith a spectrum analyzer(30 MHz–6 GHz or beyond, as needed) to confirm emissions compliance.

4. Issue of Test Report:

Upon passing all tests, JJR issues an FCC-compliant reportcontaining device info, test data, and conclusions for FCC ID application.

5. FCC ID Application (Optional):

If ID labeling is required, submit the report via a Telecommunication Certification Body (TCB). Once approved, the FCC ID is granted.

(Note: This step may be required only for certain customers or channels.)

fcc part 15Bserves as a gateway into the U.S. marketfor low-power electronic devices.

Compliance through emissions testing at an accredited lab like JJRis essential. Businesses should confirm product applicability and prepare documentation early to prevent delays from potential test failures.