Guidance

Clinical investigations for electrically powered devices

Published 30 March 2026

This guidance provides advice for people undertaking a clinical investigation of a medical device that is electrically powered, explaining the extra information that you should provide in your application. It is not prescriptive because devices vary in complexity.

Documentation for electrically powered devices

MHRA recommends that a Clinical Investigation application includes a separate document that is submitted for electrical safety and electromagnetic disturbances (EMD), which is the generic IEC term for both Electromagnetic Compatibility (EMC) and Electromagnetic Interference (EMI).

Your document should include:

What information to include

Device description

You should include:

• a clear description of function and electrical terms must be provided, this could be as block diagrams to save lengthy paragraphs
• electrical voltage and class (I, II, SELV or battery)
• details of any applied parts, along with any patient isolation design methods
• details of protective or functional earth conductors – circuit diagrams that show how the functional earth connects to the protective earth are welcome
• any relevant mechanical build specifications

Device specifications

The specifications should in include the Electrical Rating Details and the technical details of any mains PSU that has been bought ‘off the shelf’. This should have a ‘means of patient and operator protection’ which is compliant with IEC 60601.

You should also list all standards complied with, especially those used for presumption of conformity (for example, EN 60601-1: General requirements for basic safety and essential performance, and EN 60601-1-2: Electromagnetic disturbances).

Foreseeable risks and mitigation methods

A risk analysis relating to the electrical safety of the device should be provided.

Devices that use electrical energy as part of the actual treatment, or have a connection to the patient that enters the vascular system, are deemed higher risk so a detailed application is required.

Any battery powered device may have the inherent safety compromised with a data cable to a laptop so this should be considered.

Other areas that should be considered include:

• liquid ingress and how the device is sealed
• electromagnetic Interference (including battery powered devices)

Verification and testing methods

You should include:

• details of the test facility
• how the SELV power supply has been tested
• details of all relevant tests, including leakage current measurements
• test plans for electromagnetic disturbances and electromagnetic compatibility, which include the environment the device will be used in

If a battery powered device includes a charger, the safety and use of this must be explained in the instructions for use and appropriate tests completed.

You should also ensure the UK mains lead and 13A plug are compliant. This is often overlooked with devices already submitted for investigation in Europe or the USA.

UK mains supply: specific requirements

The instructions for use (IFU) must indicate how a loss of mains supply can affect safety and the mitigations required to achieve this (for example, EN 60601-1 or IEC 60601-1: clause 7.9.2.4).

In any case, interruption or restoration of the power supply should not result in loss of basic safety or essential performance (for example, EN 60601-1 or IEC 60601-1: clause 11.8 and 16.8).

List of IEC standards referenced for electrical build quality

You should include a list of standards referenced for electrical build quality. Ideally, your application should include a checklist of applicable clauses for any standard used along with an associated compliance justification column.

You can find the standards in the current list of Medical Device Standards.