Emissions, immunity, and what to do when your product fails the first scan — with realistic turnaround times and the fixes that actually work.
EMC testing has two halves. Emissions (EMI) measures the radio noise your product generates — conducted emissions on the mains cable and radiated emissions into the air. Immunity (EMS) checks whether your product keeps working when exposed to electrostatic discharge, electrical fast transients, surges, voltage dips and radiated RF fields.
A product that passes both is unlikely to interfere with other equipment and unlikely to malfunction in a realistic electromagnetic environment.
| Product | Emissions | Immunity |
|---|---|---|
| IT & multimedia equipment | EN 55032 | EN 55035 |
| Household appliances | EN 55014-1 | EN 55014-2 |
| Lighting equipment | EN 55015 | EN 61547 |
| US market (unintentional radiators) | FCC Part 15 Subpart B | Not mandatory |
| Industrial equipment | EN 61000-6-4 | EN 61000-6-2 |
| Medical devices | EN 60601-1-2 (collateral standard) | EN 60601-1-2 |
Standard EMC testing runs 3–5 working days for a product that passes. Projects slip when a sample fails and needs retest, when the product has many operating modes (each mode is a separate test configuration), or when the firmware lacks a test mode to hold the device in its worst-case emission state.
We recommend a pre-compliance scan before formal testing for anything with a switching power supply, a high-speed processor, or a motor — it is far cheaper to fix a design before the formal report is written.
The most common failure. Fixes: slow clock edge rates with series resistors, improve the return path under high-speed traces, shield the clock source, or adjust spread-spectrum settings.
Shows up as conducted emissions below 30 MHz. Fixes: common-mode choke on the input, better Y-capacitor placement, snubber circuits on the switching node.
Cables act as antennas. Fixes: ferrite cores, shielded cables with 360° termination, rerouting internal wiring away from noise sources.
Affects products with exposed connectors or user-touchable metal. Fixes: TVS diodes on I/O lines, better chassis grounding, gap design on enclosures.
Typically 3–5 working days for a compliant product. If remedial work is needed, add a few days for the fix and a partial retest of the failing items only.
Emissions testing measures unwanted radio energy your product generates. Immunity testing verifies your product continues to operate correctly when subjected to external disturbances such as ESD, surges and RF fields. Both are required under the EU EMC Directive.
Partly. Emissions test data can often be shared because EN 55032 and FCC Part 15B use similar methods and limits, but the reports are issued against different standards and the FCC procedure has its own documentation requirements. Tell us both target markets up front and we plan a single sample set.
Pre-compliance is an informal scan in the same chamber, used to find problems before the formal report. It is worth it for products with switching power supplies, high-speed digital or motors — it turns a failed certification into a quick fix instead of a redesign cycle.
No. Only the tests that failed are repeated, provided the modification does not change the product's configuration in a way that affects other test results. We document the change and reassess scope.
Yes, we test against the currently harmonised versions under our CNAS accreditation (registration L10966) and CMA qualification, and we flag upcoming version transitions so your report does not expire prematurely.
Send your product spec and target market — we reply with scope, timeline and cost within one business day.
Email Mr. TaoBeice Testing · CNAS L10966 · CMA 92 · NTEK Group Partner Lab · Shenzhen, China
+86 199-2684-3993 · taowushuang@ntek.org.cn · 中文站