What is EMC testing?

Electromagnetic compatibility (EMC) testing checks whether devices can operate as intended without reacting or interacting with electromagnetic interference (EMI). It’s required for any device that contains active electronic components. Unwanted electromagnetic energy emitted by a device may affect nearby equipment performance, compromising reliability, safety and regulatory compliance.

For instance, during EMC testing for a client, we discovered that a TFT LCD screen used in the device generated more electrical noise than anticipated. When the device was placed in its industrial enclosure, the metal back amplified interference from the screen, affecting readings taken by the main board due to their proximity. This issue wasn’t detected during internal testing.

If you want to put a product that emits or interacts with electromagnetic waves on the market, it must pass the necessary EMC tests. These tests check the device complies with regulatory standards and functions reliably in its intended environment.

How is EMC testing conducted?

Pre-compliance testing 

Pre-compliance testing is an early-stage evaluation to identify and address potential issues before your device undergoes full-scale compliance testing. 

Key Features:

• Informal Testing: Usually performed in-house with specialist, smaller equipment or at a third-party lab for more advanced analysis. Unlike full compliance testing, which requires a controlled environment such as an anechoic chamber, pre-compliance testing will use probes to pinpoint areas of concern.
• Cost-Effective: A simplified and affordable approach to identifying major design flaws early.
• Iterative Process: Allows continuous improvements to your product’s design before finalising it.
• Valuable Insights: Understand how your product interacts with electromagnetic environments, guiding better design decisions.

Taking a proactive approach allows you to test your design against key EMC standards during development, significantly reducing the risk of failing official compliance tests later. One step we highly recommend to clients is an EMC design review. This involves having an EMC specialist evaluate your device’s design before it is built or manufactured.

An EMC design review can identify and address potential issues early in the process, saving time and resources. It is one of the most effective and cost-efficient strategies for achieving pre-compliance, helping you avoid costly redesigns or delays further down the line.

Compliance testing

EMC testing takes place at a test lab. The test measures how electronics behave in their intended environments, ensuring they don’t generate significant electromagnetic interference. For example, your device is exposed to surges and interruptions on the power input, high voltage static discharges and a broad range of frequencies to ensure it will continue to operate normally in a challenging electromagnetic environment. In addition, the conducted and radiated emissions are measured to check that the device will not emit levels that will affect nearby devices.

Why is EMC testing important?

EMC testing ensures your products are compliant with regulations, reliable, safe and marketable. 37% of innovators rate meeting regulatory requirements as of high importance regarding their decision to innovate [Gov UK]. If you’re creating an electrical device to be placed on the market in the UK, your device will require EMC testing to obtain a UKCA/CE marking. After the EMC test, you will receive a product technical file detailing the tests and certifications of your device. These results allow you to claim certification for UKCA/CE and prove to UK trading standards that your product is safe. 

It’s crucial to deal with EMC testing as early as possible as redesigning your product will be expensive and time-consuming.

What happens if I skip EMC testing?

• Product recalls: Products released without proper EMC testing may fail in the field, forcing costly recalls or updates to meet compliance standards. This will also affect your brand reputation.
• Device malfunction: Without testing, your device could emit electromagnetic interference that affects nearby devices like Wi-Fi routers, mobile phones, or medical equipment. Similarly, your device might be sensitive to external electromagnetic disturbances, leading to unreliable operation in real-world environments
• Market delays: Without certification, your product’s launch could be delayed significantly.
• Post-launch fixes: Identifying and fixing EMC issues after production is far more expensive than addressing them during development. You may need to redesign hardware or firmware, re-manufacture, and re-certify your product.
• Critical failures: For medical, automotive, or aerospace devices, EMC issues can result in catastrophic failures that endanger lives.

How can I pass EMC testing the first time?

Although you can never guarantee a 100% pass rate, keeping EMC in mind throughout the design process will ensure the likeliness of a pass. It means following established best practices and having your design reviewed by an EMC specialist before manufacturing, as they can identify potential issues early on and suggest effective solutions. 

Testing your device before it goes to market is essential to mitigate risks. An exception might be for simple products, such as a battery and an LED, providing little chance of causing problems. Even in such cases, the decision should be based on solid engineering reasoning. If a product fails after launch, the consequences can be severe, requiring recalls, repairs or refunds for every device sold.

We always recommend being present at the test house — at least on the first day of testing. You can collaborate directly with the EMC engineers and use the available equipment to identify and implement suitable mitigations. A member of the team from DefProc will always attend the test house to carry out any necessary tweaks on the day. 

The worst approach is sending your device to the test house and waiting weeks for results without a plan. Ideally, either the engineer or the PCB designer should be present to support the EMC engineer. The testing process should answer the critical question: “How does this device pass so it can be placed on the market?” The goal isn’t to determine if the device passes but to identify solutions that ensure compliance and market readiness.

Conclusion

EMC testing is making a statement that your product adheres to regulatory standards. Navigating EMC testing can be challenging, but DefProc simplifies the process. With extensive knowledge of regulatory standards and best practices, we ensure your product design is optimised for EMC compliance.