EMC Compliance Guide

• EMC Fundamentals – Defines core EMC concepts, including EMI and EMS, which form the basis for emissions and immunity.

• EMC Emissions – Explains conducted emissions (150 kHz–30 MHz on power lines) and radiated emissions (30 MHz–6 GHz into free space) with applicable standards.

• EMC Immunity – Details immunity tests including ESD, surge, burst, and RF immunity with performance criteria (A–D) and typical test levels.

• EMC Test Procedure – Describes test equipment (LISN, anechoic chambers), workflow from preparation to reporting, and ISO/IEC 17025 accreditation requirements.

• EMC Compliance for Global Markets – Compares EU (RED/EMCD), US (FCC Part 15), Canada (ISED), and Asia-Pacific compliance frameworks with regional differences.

Electromagnetic Compatibility (EMC) describes the ability of electrical and electronic equipment to operate correctly within its electromagnetic environment. A device must function reliably without emitting interference that affects other equipment and without being impacted by external electromagnetic phenomena.

EMC is defined by two core concepts:

• Electromagnetic Interference (EMI): unwanted electromagnetic emissions generated by equipment

• Electromagnetic Susceptibility (EMS): the degree to which equipment is affected by external disturbances

Together, EMI and EMS determine whether a device behaves predictably under real operating conditions.

EMC emissions refer to the unintentional electromagnetic disturbances generated by electronic equipment during normal operation. These disturbances — collectively known as electromagnetic interference (EMI) — may be transmitted through cables (conducted emissions) or radiated into free space (radiated emissions). Both categories are regulated to ensure that devices do not disrupt the operation of nearby equipment.

Primary emission types:

• Conducted emissions: disturbances traveling along power or signal lines
  Typically assessed from 150 kHz to 30 MHz.

• Radiated emissions: electromagnetic energy emitted by enclosures, cables, or internal circuitry
  Typically assessed from 30 MHz to 6 GHz, depending on device class.

Early assessment of emission performance supports informed design decisions and reduces the risk of non-compliance during formal EMC testing.

Electromagnetic interference can originate from both natural and man-made sources. Understanding these origins is essential for identifying design vulnerabilities and planning effective pre-compliance testing.

Typical EMI sources include:

• Switching power supplies – generate harmonics and broadband electromagnetic disturbances due to high-frequency switching.

• Digital circuits – clock harmonics and fast switching edges from processors, memory interfaces, and high-speed data lines.

• Cables and wiring harnesses – act as unintended antennas that radiate or pick up interference, particularly when inadequately shielded or poorly routed.

• Motors, relays, and inductive loads – arcing and contact bouncing that cause broadband electromagnetic disturbances.

• Industrial equipment – welding systems, inverters, and heavy machinery producing strong broadband noise in industrial environments.

• Lighting systems – emissions from fluorescent lamps, LED drivers, and electronic ballast circuits.

• RF transmitters – intentional radiators such as mobile phones, Wi-Fi, Bluetooth, and other wireless systems operating nearby.

• Natural phenomena – lightning, electrostatic discharge, and geomagnetic disturbances.

Recognizing these EMI sources during the design phase enables targeted mitigation measures and reduces the risk of non-compliance during formal EMC testing.

Electromagnetic compatibility (EMC) immunity describes the ability of electronic equipment to withstand external electromagnetic disturbances. It is closely linked to electromagnetic susceptibility (EMS), which indicates how easily a device can be affected by such disturbances. High immunity corresponds to low susceptibility and ensures reliable performance in real operating environments.

Key EMC Immunity Tests

• Electrostatic Discharge (ESD) — sudden transfers of static electricity; evaluated according to EN 61000-4-2

• Electrical Fast Transients (Burst) — rapid voltage spikes on power or signal lines; evaluated according to EN 61000-4-4

• Surge — overvoltage events caused by switching operations or lightning; evaluated according to EN 61000-4-5

• Radiated RF Immunity — exposure to electromagnetic fields (typically 80 MHz–6 GHz); evaluated according to EN 61000-4-3

• Conducted RF Immunity — disturbances coupled into cables (150 kHz–80 MHz); evaluated according to EN 61000-4-6

Some products placed on the European market must also comply with power quality standards that complement traditional EMC testing. These requirements assess how equipment affects the stability of the public low-voltage supply network.

• Harmonics (EN 61000-3-2) – limits the harmonic currents drawn by equipment connected to public low-voltage systems, preventing distortion of the AC mains waveform.

• Voltage fluctuations and flicker (EN 61000-3-3) – defines limits for rapid voltage changes that may cause visible flicker or disturb other equipment on the same supply network.

These assessments are typically performed alongside EMC testing to support CE marking for equipment intended for residential or commercial environments.

A structured EMC test procedure ensures that compliance is evaluated consistently, reproducibly, and in accordance with international standards.

Test Equipment and Environments

EMC assessments rely on specialized instruments and controlled test environments, such as:

• Spectrum analyzers and EMI receivers – measurement of unwanted emissions across defined frequency ranges

• Signal generators – creation of controlled interference signals for immunity tests

• Anechoic and semi-anechoic chambers – shielded environments for radiated emission and immunity measurements

• Line Impedance Stabilization Networks (LISN) – defined impedance and conducted-emission measurement on AC/DC lines

• Coupling/decoupling networks (CDNs) – injection of RF disturbances for conducted immunity tests

All setups follow CISPR 16-1/16-2 requirements to ensure repeatable and comparable results across laboratories.

Pre-compliance evaluations complement design activities by identifying potential EMC issues before formal laboratory testing. Early assessments reduce redesign cycles, lower overall development costs, and improve time-to-market.

Learn more about our EMC pre-compliance testing services to support early-stage development and reduce the risk of test failures during formal compliance testing.

Electromagnetic compatibility requirements vary significantly depending on product type and target market.

In the European Union, the applicable directive depends on whether the device includes radio functionality:

• Radio equipment → RED (2014/53/EU)

• Non-radio equipment → EMCD (2014/30/EU)

Both frameworks require EMC testing, but the applicable standards and conformity routes differ.

Outside the EU, regulatory authorities follow different approaches with varying scopes for emissions, immunity, and documentation requirements. The U.S. and Canada focus solely on emissions, while Asia-Pacific markets (e.g., South Korea, China) typically require both emissions and immunity testing.

The tables below provide an aligned overview by region.