If you work with wireless products, you've dealt with FCC certification plenty. But most people mix up the division of labor between Part 15 and Part 2. Let's sort this out first.
Part 15 is a complete system. It governs both intentional RF emissions — transmit power and out-of-band spurious for Wi-Fi, Bluetooth, Zigbee modules — and unintentional EMC radiation, commonly known as Part 15-B electromagnetic compatibility. RF testing and EMC testing are both within the Part 15 framework. They're not two parallel tracks.
Part 2 is different. It's the FCC's overall administrative code. It covers equipment authorization procedures, TCB responsibilities, FCC-ID application rules, and RF exposure assessments like SAR and MPE. Part 2 itself doesn't specify RF test metrics — all RF emission limits are in Part 15. SAR/MPE falls under Part 2.1091, but the emission limits follow Part 15.247 and 15.407.
Simply put: Part 15 governs how devices are tested and where the limits sit. Part 2 governs how certification proceeds and who reviews it.
2. Part 15.247 vs. Part 15.407
Part 15 has many sub-sections, but the most commonly used are 15.247 and 15.407.
15.247 covers digital modulation devices in the 2.4 GHz band — both frequency-hopping and direct sequence spread spectrum. Bluetooth Classic and Wi-Fi 4 generally fall under this section. Power limits, hopping channel count, and dwell time are all clearly specified. The DTS device parameter requires -10dB bandwidth to be greater than or equal to 500 kHz — not 6dB bandwidth. This gets mixed up constantly.
15.407 specifically governs the 5 GHz band — the UNII bands commonly used by Wi-Fi 5 and Wi-Fi 6. Band division is far more complex than 2.4 GHz. UNII-1, UNII-2A, UNII-2C, and UNII-3 each have their own limits, and DFS (Dynamic Frequency Selection) is involved. RF spurious for bands above 6 GHz also falls under 15.407.
Then there's 15.209 — the general radiation limit fallback clause. Products not covered by a specific section must at least meet 15.209's basic limits. Many people overlook this and end up getting sent back for supplementary testing.
3. SAR and MPE — Distinguish by Use Case
Part 2.1091 defines the evaluation logic: if normal use places the device within 20 cm of the human body, SAR evaluation is required. For fixed-installation equipment or use distances exceeding 20 cm, MPE (power density) evaluation applies.
One easily overlooked point: for fixed-installation automotive equipment, even if it's close to the human body, it's classified as an installed product and evaluated under MPE — SAR isn't required. Don't apply the evaluation logic for phones and wearables directly to automotive applications.
The SAR limit is 1.6 W/kg (1g tissue average), stricter than Europe's 2.0 W/kg (10g). Test scheduling takes longer and costs are higher — plan ahead.
4. Key Changes to Watch in 2025-2026
FCC rules have shifted significantly over the past two years, but some claims have been exaggerated. Pay particular attention to the following.
KDB 447498 Isn't a 2025 Matter
KDB 447498 D01 V07 actually took effect on March 31, 2022 — not March 2025. The new version tightened SAR evaluation rules, but the regulatory text doesn't contain any "30% precision improvement" language. That's an informal industry description — don't cite it as an official clause.
6 GHz Band Testing
6 GHz band testing is now part of FCC certification scope. Wi-Fi 6E and Wi-Fi 7 products cover the 5925-7125 MHz band.
The AFC (Automatic Frequency Coordination) mechanism only applies to standard-power AP devices. Low-power VLP devices don't need AFC functionality — don't add unnecessary requirements to devices that don't need them. When selecting a lab, ask whether they have 6 GHz capability.
Cyber Trust Mark Is Still Voluntary
For connected device cybersecurity, the Cyber Trust Mark is currently a voluntary program. FCC hasn't made cybersecurity a mandatory FCC-ID admission threshold, and there's no mandatory enforcement landing in 2026.
FCC-ID review doesn't currently examine firmware passwords or secure boot. Mandatory enforcement may come after FCC officially legislates — don't conflate voluntary programs with certification thresholds.
HAC Applies Only to Handheld Phones
HAC (Hearing Aid Compatibility) testing becomes mandatory for new phones hitting the market starting December 14, 2026. Both RF coupling and T-coil coupling must be tested.
But 47 CFR 20.19 applies only to mobile handheld phones. Automotive modules, tablets, and Bluetooth earphones are not within the HAC mandatory scope — don't expand the range. M3/T3 is the minimum grade requirement.
5. FCC Certification Testing Scope and Details
EMC Radiated Emission Upper Limit Is Still 1 GHz
Conducted emission from 150 kHz to 30 MHz hasn't changed in years. Part 15-B's standard EMC radiated emission testing upper limit remains 1 GHz — it hasn't been extended to 40 GHz.
The 40 GHz figure is the spurious evaluation range from the RF clauses, governed by 15.407. It's not the same thing as Part 15-B's EMC radiated emission. Don't mix RF spurious with EMC radiation.
FCC ID Registration Rules
The FCC ID consists of a Grantee Code and a Product Code, totaling no more than 14 characters. The Grantee Code is a 3-character alphanumeric assigned by the FCC. The Product Code is set by the manufacturer.
FCC's deduplication logic is the Grantee Code plus the complete model number combination. A Product Code that duplicates someone else's won't trigger an error, as long as the complete device model under the same Grantee is unique. No need to panic if your Product Code happens to match — just check the FCC database before registration to confirm no collision. That's a good habit.
Labels Must Be Permanent
FCC ID labels must be permanently marked on the device body, minimum size 5 mm. Laser etching, in-mold injection, and stamping all work. Stickers don't count as permanent.
The label must be visible without disassembly. If the device is too small to fit the complete ID, an abbreviated form is acceptable, but the electronic label must contain complete information.
Automotive Product Certification Paths
Automotive product certification paths are easy to get wrong. Automotive infotainment systems with Wi-Fi hotspots or Bluetooth must go through FCC ID — no room for negotiation.
Pure display-function devices — like rear entertainment screens without wireless modules — can go through SDoC self-declaration.
How are reserved interfaces judged? It depends on how far the hardware actually goes. If only connectors are reserved, no RF traces on the PCB, and no RF power supply — the device doesn't contain intentional emission circuits and can go through SDoC normally. But if the PCB already has RF traces laid out, even if chips won't be mounted later, FCC-ID is required. The key is whether the PCB has traces, not whether there's a reserved connector.
Laboratory Restriction List
Starting September 2025, the FCC introduced new rules for restricted laboratories. If the testing lab itself is on the FCC-USML restricted list, its reports won't be accepted.
Note the distinction: lab supply chain components sourced from restricted entities don't automatically invalidate reports. Don't over-extend the condition. Check the list when you need to — no need for paranoia.
For more on FCC certification standards and Part 15/Part 2 testing projects, contact BlueAsia Testing & Certification — consultant Benson at 13534225140.
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