Is it really safe? Electrical safety in MedTech

An overview of electrical safety testing for medical devices. Third-party testing can often be a lengthy and costly process and there are many pitfalls along the way. These can often be avoided with proper planning and knowledge of the testing procedure and associated requirements. This article provides a brief overview of how electrical safety testing can be done.

CE marking

A recurring concept in electrical safety testing is CE marking* It is the manufacturer's responsibility to CE mark his product. What distinguishes the requirements for electrical medical devices from other electronics is that a third party must in principle always test the product against the relevant standards before CE marking can be carried out.

Let's say your medical device is relatively complete and all that remains is for a third party to certify that the product is safe. Let's go into a little more detail about what is required for this.

The way through the test lab

It all starts when the product is sent to a testing laboratory. TÜV, Intertek and VDE are some examples of such laboratories that perform electrical safety testing. These laboratories test products against relevant standards harmonised with current EU directives and regulations.

Theoretically, it is possible to demonstrate that a product complies with the current regulatory framework without testing it against applicable harmonised standards. The number of manufacturers who choose to go down this route is vanishingly small for the simple reason that it makes the whole process much more difficult. This is because the EU medical device regulatory framework includes something called the presumption principle. This means that if a product complies with its applicable harmonised standards, it also complies with the requirements of the EU regulatory framework regarding electrical safety (assuming that this is the aspect evaluated in the harmonised standard).

Therefore, if your medical device contains electronics, it should be tested against the IEC 60601-1 standard. This standard provides the basis for electrical safety. In addition to this, there are collateral and particulate standards that apply depending on the type of product. The collateral and particulars are branches of the basic standard IEC 60601-1. Ionising radiation, the use of anaesthetics and alarms have specific requirements which are then addressed in these branches.

Once the applicable standards have been determined, the laboratory conducting the test will review these standards and assess which clauses will be applicable to your product. Not all requirements will be applicable. Much is sorted out as "not applicable". Therefore, it may be a good idea as a designer to keep track of the applicable standards and check yourself which requirements will be applicable. Is the product powered by mains voltage or is it battery powered? Of course, the different options will result in completely different requirements for the safety of the electronics.

Some important points that the test evaluates in the product are:

  • Associated documentation such as Instruction Manual and Risk Management
  • Electrical safety with main focus on insulation and leakage currents
  • Mechanical strength and mechanical hazards
  • Elevated temperatures that can cause fire, burns or overheating of components. Corresponding requirements also exist for unusually low temperatures.
  • Hazardous liquids, gases, radiation and noise

Results of the test

The basic pillar of third-party testing is that the third party, i.e. the testing laboratory, must not influence the design of the product. Therefore, the test usually results in a compilation of deviations that points out which clauses of the applicable standards the product does not meet. It is then up to the manufacturer to deal with these deviations to ensure that the product is redesigned to meet the requirements of the standards. Once this has been done, the product can be retested on the points rejected by the test laboratory. A bit like the car inspection (which is actually also third party testing). In a sense, testing becomes an iterative process with a lot of back and forth with the test laboratory.

Some tips on what to consider to facilitate the testing process

- Have documentation ready for all components that may be critical to safety. IEC certificates and data sheets for the components are often a must.

- Electrical schematics are essential and it helps a lot if you can think through what faults could occur in the product if components overload or fail.

- Be able to describe in an educational way how the product is set up in its extreme modes that involve maximum power consumption, maximum gas supply, maximised or minimised time settings, etc. This will be important for those who test the product. For the test laboratory, the product is often completely unknown while you are the experts on your product!

- Be prepared to communicate a lot with the testing laboratory and do not take any discrepancies on the product personally.

- Be prepared that the manual will need to be revised. It is extremely rare for manuals to be free of errors, ambiguities or missing important elements.

- Not sure if the product passes a particular test? Try it yourself! Of course, this is not an impartial test result for the product, but it can give you an indication of how close your product is to meeting the requirements. You can get quite far with simpler equipment such as multimeters, simpler circuits with resistors and capacitors and adjustable voltage assemblies.

So to return to the question posed at the beginning: is it really safe? Feel free to get in touch if you need advice or support. We are here for you.

The term CE is originally an abbreviation of the French Conformité Européenne and must be carried by most electronic products intended to be sold, not only within the EU, but actually within the EEA (European Economic Area) which also includes Iceland, Lichtenstein and Norway. In addition, there are many countries outside the EEA that value a CE mark highly, although it may not be sufficient on its own to certify that product safety has been met.

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