IEC 60601 – Overview of the Main Requirements

The IEC 60601 has played and still currently plays a key role for safety of active medical devices. The IEC 60601 is basically a group of standards which is dealing with the safety of electrical medical equipment. Compliance to IEC 60601 is one of the pillar of the design control process for active medical devices.

IEC 60601-1 is the parent of a series of standards relating to the safety of Medical Electrical Equipment. You can see a general overview of the relations between the different standards of the 60601 family in the scheme reported below. 

The IEC 60601 series of standards is recognized by multiple countries like United States, EU, Canada and other countries. 

Moreover, there is the possibility to use a simplified approach to obtain multiple national certifications within a single test report and certificate. This approach is called CB Scheme and it comes from the IECEE (IEC System of Conformity Assessment Schemes for Electromechical Equipment and Components) . The CB scheme is basically an international system for mutual acceptance of test reports and certificates dealing with the safety of electrical and electronic components, equipment and products.

In this article we will go through the general structure and the main requirements of the IEC 60601-1, which is the general from where all the related and collateral standards derive from.

The key sections of the IEC 60601-1 that will be discussed in this articles can be summarized as follows: 

• Section 4 – General Requirements
• Section 5 – General Requirements for Testing ME equipment
• Section 6 – Classification of ME Equipments and ME Systems
• Section 7 –  ME Equipment identification, marking and documents

There are other sections (until 17) which however will not be discussed and taken in consideration in this article. In fact, in this post, we will go through all the sections mentioned above and provide an overview of the main requirements.

Preliminary activities before the start of the IEC 60601 tests

There are typically some activities that need to be performed before starting the real tests for the 60601-1; these tests are normally performed by an external laboratory. 

One of the key preliminary activity is the creation of a insulation diagram. The standard is providing requirements related to both operator and patient protection and defines “means of protection” (MOP) as:

• One MOP – basic insulation
• Two MOP – double or reinforced insulation

IF the specific ME equipment does not have two MOP, it is necessary to have protectively earthed parts for that specific isolation barrier you need to consider.

Another very important activity is to define the table of critical components. Usually these are components that could affect the safety of the device. For these components, it is necessary to submit to the external lab documentation such us UL certification, technical drawing and/or datasheet, or specific tests certifications performed on those components. 

General Requirements of the IEC 60601-1

The key requirement of this section is the one related to the application of ISO 14971 and the related process for the management of risk. It is thus necessary to identify the risk, evaluate them and perform an overall evaluation of the residual risks. 

The Essential Performance of the device shall be defined, which is functionality whose loss or degradation results in unacceptable risk. 

An important requirement associated with the concept of essential performance is the so-called Single fault Safe, where basically each failure of the device does not cause unacceptable risks. Failures of the device shall be selected according to the risk analysis and tested, in order to evaluate the Single Fault Condition. Finally, in this section, specific requirements are mentioned for the Power Supply and the standard specified the voltage limits for medical electrical equipment to be connected to supply mains.

Classification of the device according to the IEC 60601-1

In this part, there are some requirements related to sample size and types, as well as on the environmental conditions or other conditions that may be used during the test. 

However, the most important requirements for this sections are the ones related to the categorizing the class of equipment (I or II); the type of Applied Part (B, BF or CF); the protection against fluids and dust (Ingress Protection IP rating); and whether or not it requires Sterilization and is suitable for use in Oxygen-enriched atmospheres.

This is very important because the result of the categorization impacts the type of tests to be performed and the related acceptability method for those tests. 

The class of medical electrical equipment is dependent from the method of protection against electric shock that is used. Class I medical electrical (ME) equipment has a protective earth. The basic means of protection is the insulation between live parts and exposed conductive parts such as the metal enclosure. On the other hand, for Class II ME equipment, the method of protection against electric shock is either double insulation or reinforced insulation. 

The degree of protection for medical electrical equipment is defined by the type designation. There are different  types of designation, due to the different pieces of medical electrical equipment that have different areas of application and therefore different electrical safety requirements. The different classes are:

• Type CF: is the most stringent classification, being required for those applications where the applied part is in direct conductive contact with the heart or other applications as considered necessary.
• Type BF: is less stringent than CF, and is generally for devices that have conductive contact with the patient, or having medium or long term contact with the patient.
• Type B: is the least stringent classification, and is used for applied parts that are generally not conductive and can be immediately released from the patient.

Regarding the IP classification,  it is related to the classification of enclosure according to their related protection against harmful ingress of water and particulate matter ; this is detailed in the IEC 60529.

ME Equipment identification, marking and documents

This section contains different requirements mainly related to the labels and marking in terms of durability and legibility. Moreover, there are as well specific requirements related to the power supply or the power cord entry. 

There are different requirements for the legibility of the markings, depending on the type of ME equipment (Fixed or transportable ME Equipment). In general, the legibility of the marking is tested in the following way: 

The ME EQUIPMENT or its part is positioned so that the viewpoint is the intended position of the OPERATOR; or the viewpoint is at any point within the base of a cone subtended by an angle of 30°  to the axis normal to the centre of the plane of the marking and at a distance of 1 m. The ambient illuminance is the least favourable level in the range of 100 lx to 1 500 lx. The observer has a visual acuity of 0 on the log Minimum Angle of Resolution (log MAR) scale or 6/6 (20/20), corrected if necessary.

The durability of the marking is also tested, using the following methodology: 

Markings are rubbed by hand, without undue pressure, first for 15 s with a cloth rag soaked with distilled water, then for 15 s with a cloth rag soaked with methylated spirit and then for 15 s with a cloth rag soaked with isopropyl alcohol.

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