In engineering practice, EMC testing is often a true stress test for development teams. Despite a carefully designed circuit, modern components, and functional compliance, a device may fail. This can happen simply due to excessive emissions or insufficient immunity to electromagnetic disturbances. What’s more, these issues don’t always stem from obvious design flaws. They often result from seemingly minor details, such as PCB trace layout, grounding strategy, or voltage variations in the power supply. As EMC expert Henry Ott explains:
“A product that is not electromagnetically compatible is not really functional in the real world, regardless of how well it performs in isolation.” (Electromagnetic Compatibility Engineering)
This article provides a practical overview of EMC testing: how the tests are performed in certified laboratories, the most common sources of non-compliance, and proven strategies to mitigate them. We also explain how pre-compliance testing and a design-conscious approach can significantly streamline the overall certification process across a broad range of electronic products.
Harmonized standards play a key role in the process of assessing product conformity with the requirements of the EMC Directive 2014/30/EU. In the case of wireless devices, compliance with the Radio Equipment Directive (RED) 2014/53/EU is also essential. These are relevant standards developed by European standardization organizations (such as CENELEC). They are officially recognized by the European Commission and published in the Official Journal of the EU. According to Dr. Arturo Mediano, EMC consultant and researcher at the University of Zaragoza: “Compliance with standards is not just a legal requirement; it is a method to ensure technical robustness and interoperability.”
While the use of harmonized standards is not mandatory, it provides a presumption of conformity. It means that the product is considered to meet the essential requirements of the directive. This significantly simplifies the conformity assessment process and the preparation of technical documentation.
In practice, many different EMC standards apply depending on the type of product and its operating environment. For example, for electronic equipment used in residential environments, Class B limits typically apply. Standards like EN 55032 (for emissions) and EN 55035 (for immunity) are commonly used. Industrial equipment is often subject to EN 61000-6-4 (emission) and EN 61000-6-2 (immunity). For medical devices, EN 60601-1-2 is required, while railway equipment must meet EN 50121-3-2.
Selecting the appropriate EMC standard for a product should be based on several factors: the function of the device, the environment in which it will be used (residential, industrial, or specialized), and its technical characteristics. A best practice is to start by reviewing the current list of harmonized standards related to the EMC Directive. This list is available on the European Commission’s website. In case of uncertainty, it is advisable to consult with a testing laboratory or a notified body. They can help identify the correct set of standards and define the scope of testing necessary to achieve CE marking.
In order for a product to be legally placed on the market in the European Union with the CE marking, it must meet the requirements of the EMC Directive 2014/30/EU. These requirements include electromagnetic compatibility (EMC) testing. The primary objective of these tests is to verify that the device does not interfere with the operation of other equipment (emissions). It must also be resistant to electromagnetic disturbances from its environment (immunity). Compliance with the EMC Directive is often required alongside other applicable directives, such as the Low Voltage Directive (LVD) or Radio Equipment Directive (RED), depending on the product type. Importantly, reducing electromagnetic emissions also contributes to environmental protection by minimizing energy waste and avoiding interference with critical wireless infrastructure. This design philosophy is underscored by Mark Montrose, a recognized EMC expert and author of EMC Made Simple:
“Good EMC design is not about adding filters at the end. It’s about engineering from the beginning with the electromagnetic environment in mind.”
Electromagnetic emission tests are divided into two main categories: radiated and conducted emissions. Radiated emissions refer to electromagnetic waves emitted by the device into the air and are measured in the frequency range from several MHz to several GHz. Conducted emissions, on the other hand, concern disturbances transmitted through power and signal cables, especially in the lower frequency range (up to 30 MHz).
Immunity tests assess the device’s resistance to various types of electromagnetic disturbances. These tests simulate real-life interference conditions that equipment may encounter. The most common include:
The scope and severity of testing are determined by the intended environment in which the product will operate. Different requirements apply to household equipment (such as computers or consumer electronics) and to industrial devices used in high-interference environments. For instance, industrial products must demonstrate a higher level of immunity compared to consumer devices, and are therefore subject to more stringent testing.
If you want to learn more about the HIL method, we encourage you to read our article:
The process begins with a risk analysis and product classification. The manufacturer must determine the product’s intended environment. This may include residential, industrial, medical, or railway applications. They must also define the usage profile and identify potential sources of electromagnetic emissions and susceptibility. This analysis forms the basis for selecting the appropriate harmonized standards and the required testing levels defined for the target environment.
Based on this, the manufacturer selects the appropriate conformity assessment procedure. For most products, the so-called “Module A” (internal production control) applies, which allows the manufacturer to self-declare conformity without involving a notified body. In more complex cases, a notified body may be voluntarily engaged to support the assessment. This applies, for example, when no applicable harmonized standards exist or when the product poses a higher risk.
The next stage involves laboratory testing, which should be carried out in an accredited EMC test laboratory (in compliance with ISO/IEC 17025). The lab conducts emission and immunity tests following the selected standards. It then issues a detailed test report which serves as technical evidence in the product’s technical file.
In the event of non-compliance (e.g., excessive emission levels or insufficient immunity), the manufacturer is required to implement corrective actions. This may include redesigning the circuit, adding EMC filters or shielding, or adjusting PCB layout and component placement. Once modifications are made, full re-testing must be performed.
Upon successful completion of testing, the manufacturer compiles the technical documentation. They then issue and sign the EU Declaration of Conformity. Finally, the CE marking is affixed to the product. Only then can the product be legally placed on the EU market.
During the EMC conformity assessment process for CE marking, manufacturers often make mistakes that can result in test failures, delays in market entry, or even legal liability. A 2023 survey of European EMC test labs revealed that documentation issues account for 35% of failed compliance audits, while misapplication of harmonized standards causes nearly 40% of first-time test failures. The most common issues include:
To avoid these pitfalls, InTechHouse recommends working with an experienced EMC test laboratory, planning the conformity assessment process early in the product development cycle, and conducting a thorough analysis of harmonized standards already at the design stage.
Properly conducted EMC testing is not just a “checked box” on a compliance list. It is a genuine competitive advantage in a world where the stability and reliability of devices are just as important as their functionality. Therefore, it is essential to remember that a well-planned approach to EMC is crucial. Starting already at the design stage significantly increases the chances that the product conforms to all applicable electromagnetic compatibility standards.
Thanks to advanced technological resources, tailored solutions, and specialized expertise, InTechHouse provides strong support to its clients. The company helps them not only meet regulatory requirements but also significantly reduce time-to-market. Additionally, we support the design process early on to eliminate the risk of costly revisions and delays. Trust a proven partner—schedule a free consultation with us today.
Do embedded modules need to undergo EMC testing if they are not sold as finished products?
If an embedded module is intended for integration into another device, it does not need to independently comply with the EMC Directive. However, the manufacturer of the final product must carry out the conformity assessment of the entire system.
Do I need to use an accredited laboratory for EMC testing?
It is not mandatory, but it is highly recommended. Accredited laboratories ensure reliable results and are recognized by EU authorities.
How long does the EMC testing process take?
It depends on the complexity of the device. Basic testing can take a few days, while more complex cases may require 1 to 3 weeks, depending on the number of applicable standards and necessary modifications.
Does the EMC Directive apply only to mains-powered products?
No. It also applies to battery-powered devices, wireless equipment, and those communicating via signal cables—if they can emit or be affected by electromagnetic disturbances.
How long must EMC documentation be retained?
According to the regulations, the technical documentation and the EU Declaration of Conformity must be retained for at least 10 years from the date the product is placed on the market.
