---
title: How to Design for EMC Compliance from the Start
description: Design choices that prevent EMC failures in medical devices: PCB layout, shielding, grounding, cables, and pre-test prep aligned to MDR Annex I §14.5.
authors: Tibor Zechmeister, Felix Lenhard
category: Electrical Safety & Systems Engineering
primary_keyword: EMC compliance design medical device MDR
canonical_url: https://zechmeister-solutions.com/en/blog/design-for-emc-compliance
source: zechmeister-solutions.com
license: All rights reserved. Content may be cited with attribution and a link to the canonical URL.
---

# How to Design for EMC Compliance from the Start

*By Tibor Zechmeister (EU MDR Expert, Notified Body Lead Auditor) and Felix Lenhard.*

> **EMC compliance is decided in the schematic, not the lab. If you design PCB layout, shielding, grounding and cable choices around EN 60601-1-2:2015+A1:2021 from the first prototype, your first test campaign becomes a verification exercise. If you don't, it becomes a six-month redesign.**

**By Tibor Zechmeister and Felix Lenhard.**

## TL;DR
- MDR Annex I §14.5 requires devices to be designed so that electromagnetic disturbances do not impair basic safety or essential performance.
- EN 60601-1-2:2015+A1:2021 is the harmonised EMC collateral standard that gives presumption of conformity for ME equipment.
- Most first-visit EMC failures trace back to four design choices: PCB layout, grounding topology, shielding strategy, and cable selection.
- Pre-compliance scans on an engineering bench catch 80 percent of problems at 5 percent of a full lab campaign's cost.
- Immunity failures are usually about missed test levels for the intended use environment, not about the DUT being "broken".
- EMC evidence lives in the technical file under Annex II and must be traceable to the risk file per EN ISO 14971:2019+A11:2021.

## Why this matters

A startup Felix coached had a Class IIa wearable that passed every internal test. They booked four days at an accredited EMC lab in Bavaria. On day one, the device re-booted during the 3 V/m radiated immunity sweep at 900 MHz. By day two, they had burned the slot, lost 14,000 EUR, and learned their test engineer had laid out the power rails with a 12 mm gap between the MCU ground and the analog ground on a two-layer board. The fix was a four-layer redesign, a new prototype run, and eleven weeks of delay.

None of that was an EMC lab problem. It was a design problem that showed up in the EMC lab.

EMC is the most predictable failure mode in MDR certification because the physics are well understood and the test levels are fixed. The founders who ship on time are the ones who treat EN 60601-1-2:2015+A1:2021 as a design input, not a late-stage hurdle.

## What MDR actually says

MDR Annex I General Safety and Performance Requirement §14.5 requires that devices be designed and manufactured so that they minimise the risks linked to the reasonably foreseeable environmental conditions, including electromagnetic disturbances that can be expected during normal use. The device must maintain its basic safety and essential performance when exposed to those disturbances and must not itself emit disturbances that could impair other equipment.

That is the legal obligation. EN 60601-1-2:2015+A1:2021 is the harmonised collateral standard that operationalises §14.5 for medical electrical equipment. When you test to it and document the results, you get the presumption of conformity. The notified body is obliged to accept compliance with the harmonised standard as evidence that the GSPR is met, unless they have specific reason to doubt it.

Two anchors matter for design decisions:

1. **Essential performance** must be defined before you test. EN 60601-1 and EN 60601-1-2 both require you to declare what function must continue to operate during and after EMC exposure. If you have not declared it, the lab cannot test it, and the report is worthless.
2. **The intended use environment** determines the test levels. Home healthcare environments have higher immunity requirements than professional healthcare facilities. If you tell the lab "professional use" and your IFU later says "home use", you will re-test.

The standard references back into MDR Annex I §17.1 (software and programmable systems) where electronic programmable medical systems (PEMS) are involved. EMC is also a risk control, so everything you do here must be traceable in the risk management file under EN ISO 14971:2019+A11:2021.

## A worked example

Consider a battery-powered, Bluetooth-connected Class IIa infusion monitor intended for home healthcare. Essential performance is defined as "alarm within 10 seconds of detected occlusion, with an audible signal at ≥65 dB(A) at 1 m".

The designer has four EMC-critical decisions to make before the first prototype:

**1. PCB layout.** Four-layer stackup with a continuous ground plane on layer 2. The MCU, the analog front end and the wireless radio sit on layer 1 with tight return paths. No ground plane splits under high-speed signals. Analog and digital grounds join at a single star point under the ADC. The Bluetooth antenna keepout is honoured. Decoupling capacitors (100 nF + 10 µF) on every power pin, placed within 3 mm of the pin with short via stitching to the ground plane.

**2. Grounding topology.** Chassis ground (the metal enclosure shield) bonds to PCB ground through a single low-impedance point near the charging port. This prevents ground loops during conducted immunity testing at the 1 kHz to 80 MHz range. The patient-applied part has a reinforced barrier and does not share ground with the main PCB.

**3. Shielding strategy.** The enclosure is injection-moulded plastic with conductive paint on the inside, bonded to chassis ground. The radio section has a small can shield soldered over the RF front end. The display cable is a flat flex with a dedicated ground return, not a ribbon with signals sharing one ground wire.

**4. Cable choices.** The charging cable is 1.2 m with a ferrite bead moulded into the strain relief at the device end. The USB-C port has common-mode chokes on D+/D- and CC lines. No cable exceeds 3 m, which keeps the device under the simpler test setup per EN 60601-1-2:2015+A1:2021 Table 4.

Before booking the lab, the team runs pre-compliance scans on an engineering bench: a near-field probe set (about 1,500 EUR), a spectrum analyser (rented), and a scripted radiated emissions sweep in a 3 m makeshift chamber. They find a 240 MHz harmonic from the SPI bus leaking through a poorly decoupled power rail. They fix it with a 10 nF cap and a series ferrite. Total cost: two days of engineering time and 4 EUR in components.

At the accredited lab, the device passes radiated emissions, conducted emissions, radiated immunity at 10 V/m (home healthcare level), electrostatic discharge at ±8 kV contact / ±15 kV air, and electrical fast transient / burst immunity. One finding during surge testing is resolved with a TVS diode added to the charging input. Total lab time: three days. Total EMC budget used: about 60 percent of what was allocated.

This is what designing for EMC looks like.

## The Subtract to Ship playbook

Do less, but do the right things at the right time. Here is the lean path.

**Before schematic (Week 0 of hardware design).**
- Declare essential performance in writing. One paragraph. Put it in the design input document.
- Define the intended use environment precisely: home healthcare, professional healthcare facility, special environment (MRI, surgical). This drives the test levels in EN 60601-1-2:2015+A1:2021.
- Identify worst-case EMC threats in the risk file: the ESD from a dry carpet, the GSM phone held 30 cm away, the mains surge from a lightning strike. Link each to a risk control.

**During schematic and layout (Weeks 1-6).**
- Four layers minimum for any device with wireless, high-speed digital, or sensitive analog.
- Continuous ground plane on an adjacent layer to every signal layer.
- Decouple every power pin. Not sometimes. Every pin.
- Keep return paths short. If you cannot see the return path in your layout, you have a problem.
- Choose shielded cables or add ferrites at connector entries for any cable longer than the enclosure.

**Before the lab (Weeks 6-10).**
- Run pre-compliance scans. Near-field probe the board for hot spots. Check conducted emissions on the power input with a line impedance stabilisation network (LISN) if you can borrow one.
- Document the test configuration exactly as it will appear at the accredited lab. Same cables. Same accessories. Same software build.
- Have a risk-controlled mitigation plan for the top three likely failures. Ferrites, caps, shielding tape. Bring them to the lab.

**At the lab (Week 10 or later).**
- Bring two devices. One as the DUT, one as a hot spare.
- Bring the test engineer who designed the PCB. Not the CEO. Not the project manager. The engineer who can change a component value in ten minutes.
- Record everything. If something fails, you want the exact frequency, level, and orientation for the redesign loop.

**After the lab.**
- File the EMC test report in the technical file under Annex II §4 (verification and validation).
- Link the report to the risk management file. Every test that passes is a risk control verified. Every test that fails is a risk you need to re-evaluate.
- Update the IFU with the EMC declaration tables from EN 60601-1-2:2015+A1:2021. These are mandatory for the accompanying information.

## Reality Check

1. Have you declared essential performance in one sentence that an EMC test engineer could turn into a pass/fail criterion tomorrow?
2. Does your PCB have a continuous ground plane adjacent to every signal layer, or are you hoping a two-layer design will pass?
3. Can you name the test levels for radiated immunity that apply to your intended use environment, without looking them up?
4. Have you run any pre-compliance measurement. Even a 50 EUR near-field probe sweep. On your current prototype?
5. Is your EMC budget line item in your burn rate, or is it a surprise cost you will discover at Month 14?
6. If your device fails ESD at ±8 kV contact during the lab visit, do you know which component on the PCB is the most likely entry point?
7. Have you linked the EMC test plan to specific risk controls in the risk management file, or is EMC sitting in a separate silo?
8. Does your IFU include the EMC declaration tables required by the harmonised standard, or is that a task still on someone's to-do list?

## Frequently Asked Questions

**Do I need EN 60601-1-2 if my device is battery-powered and wireless only?**
Yes. The standard applies to all medical electrical equipment regardless of power source. Battery operation exempts you from some conducted emissions tests on the AC mains input, but radiated emissions, radiated immunity, ESD and magnetic field immunity still apply.

**Can I use a non-accredited lab for the final EMC report?**
Your notified body will expect an ISO 17025-accredited lab for the final compliance report. Non-accredited labs are fine for pre-compliance scans, but the report that goes into the technical file must come from an accredited facility.

**How much does a full EMC test campaign cost in 2026?**
For a typical Class IIa device, expect 8,000 to 25,000 EUR at an accredited EU lab for a first campaign covering EN 60601-1-2:2015+A1:2021. Re-tests after failure add 2,000 to 5,000 EUR each. This is why pre-compliance matters.

**Is EMC a design control or a verification activity?**
Both. It starts as a design input (the requirement to meet EN 60601-1-2:2015+A1:2021 for your intended use environment), flows through design output (the schematic and layout choices), and ends in verification (the lab test). If you treat it only as verification, you will fail.

**What if my device has wireless and I have to meet the Radio Equipment Directive too?**
You will need an EN 301 489 series test in addition to EN 60601-1-2. Most accredited medical EMC labs can run both in the same session. Plan for it; do not discover it.

**Does EN 60601-1-2:2015+A1:2021 cover cybersecurity-related EMC risks?**
Partially. The immunity tests verify that the device maintains essential performance under electromagnetic disturbance, which includes some intentional radiated attacks. Full cybersecurity is covered separately under EN IEC 81001-5-1:2022 and MDCG 2019-16 Rev.1.

## Related reading
- [EMC Requirements Under IEC 60601-1-2](/blog/emc-requirements-iec-60601-1-2) – the standard explained in depth.
- [EMC Testing for Medical Devices](/blog/emc-testing-medical-devices) – what actually happens in the test chamber.
- [The IEC 60601-1 Test Lab Process](/blog/iec-60601-1-test-lab-process) – preparing for the full electrical safety campaign.
- [Common IEC 60601-1 Test Failures](/blog/common-iec-60601-1-test-failures) – the failures Tibor sees most often and how to avoid them.
- [MDR Electrical Safety Requirements](/blog/mdr-electrical-safety-requirements) – how electrical safety fits into Annex I.

## Sources
1. Regulation (EU) 2017/745 on medical devices, consolidated text. Annex I, §14.5 and §17.1.
2. EN 60601-1-2:2015+A1:2021. Medical electrical equipment. Part 1-2: General requirements for basic safety and essential performance. Collateral Standard: Electromagnetic disturbances. Requirements and tests.
3. EN 60601-1:2006+A1+A12+A2+A13:2024. Medical electrical equipment. Part 1: General requirements for basic safety and essential performance.
4. EN ISO 14971:2019+A11:2021. Medical devices. Application of risk management to medical devices.

---

*This post is part of the [Electrical Safety & Systems Engineering](https://zechmeister-solutions.com/en/blog/category/electrical-safety) cluster in the [Subtract to Ship: MDR Blog](https://zechmeister-solutions.com/en/blog). For EU MDR certification consulting, see [zechmeister-solutions.com](https://zechmeister-solutions.com).*