medical electrical equipment

IEC 60601 medical electrical equipment classification frequently asked questions are discussed in this blog. 

All clause references in this blog are to both IEC 60601-1:2005 (3^rd edition) and IEC 60601-1:2005 (3^rd edition) + Amendment 1:2012, or the consolidated version IEC 60601-1:2012 ed. 3.1, but the actual text comes from edition 3.1.

Note 1: ALL CAPITAL LETTERS identifies a defined term for the IEC 60601 series of standards within this blog.

Note 2: The current version of IEC 60601-1 is now ed 3.2.

What are the various classifications that are used in IEC 60601-1, edition 3.1?

The table at the beginning of this blog posting identifies the five parts of the Classification section. Each classification is described in more detail below.

Why do I need to classify my product for IEC 60601-1, 3^rd ed.?

The standard says you have to classify “…ME EQUIPMENT, or parts thereof, including applied parts…” as noted in sub-clause 6.1. But a more practical reason you would want to classify your products that fall under the scope of IEC 60601-1 is it is a helpful tool in identifying the requirements that apply to the device and helps us in determining the test plan for the product to be tested.

What is an applied part?

The definition of an APPLIED PART is in sub-clause 3.8 of the standard. It states that an APPLIED PART is “part of ME EQUIPMENT that in NORMAL USE necessarily comes into physical contact with the PATIENT for ME EQUIPMENT or an ME SYSTEM to perform its function.” So, it can be a cable, lead, electrode, or many other parts of an ME EQUIPMENT, or an ME SYSTEM that is intended, by the manufacturer, in its NORMAL USE to come in contact with the PATIENT.

What are the classifications for Protection Against Electric Shock?

Two classifications fall under sub-clause 6.2 of the standard: 1) the power source, and 2) applied parts. Power sources can be an external power source and is either classified as a class I or class II ME EQUIPMENT or an internal power source, which is classified as INTERNALLY POWERED MEDICAL EQUIPMENT.

Power Sources – External Class I, External Class II, or Internal

Class I provides its protection against electric shock by having an additional safety ground (known as PROTECTIVELY EARTHED) that is connected to the internal and/or external conductive parts (metal) of the power source. Class II provides its protection against electric shock by having an additional layer of insulation beyond that of BASIC INSULATION (a single layer of insulation) and is provided either by DOUBLE INSULATION (two layers of insulation) or by REINFORCED INSULATION (the same as for DOUBLE INSULATION, but as one insulation system that is twice as thick, typically). An internal power source is usually a battery.

Applied Parts – B, BF, CF (also defibrillation-proof)

The second classification for protection against electric shock is for APPLIED PARTS. APPLIED PARTS are classified in one of six ways, and a product can have more than one type of APPLIED PARTS. The classifications for applied parts are type B, BF, or CF. Each of these three classifications can be DEFIBRILLATION-PROOF APPLIED PARTS for a total of 6 classifications. There are six separate symbols for these APPLIED PARTS, and they are noted in the table below, which comes from Table D.1 of Annex D of the standard.

Why do we have classifications for protection against electric shock?

Protection against electrical shock is important because electric shock is one of the main areas of concern in most electrical safety standards as the shock hazard can cause harm to the OPERATOR or PATIENT or even death. The main reason is we want to protect the PATIENT, who may have a depressed immune system from getting an electric shock that could injure or potentially kill the PATIENT. The depressed immune system makes them more likely to be harmed by an electric shock. We also want to consider the OPERATOR of the device, but they should not have a depressed immune system, so the worst-case to consider is the PATIENT.

What are the classifications for protection against harmful ingress of water or particulate matter?

There is a wide variety of these classifications (per sub-clause 6.3 of IEC 60601-1), and they are based on the standard IEC 60529 titled “Degrees of protection provided by enclosures (IP Code).” The IP Codes range from IP00 to IP68, which means respectively no protection against contact and ingress of objects along with not being protected against liquid ingress (IP00) to No ingress of dust; complete protection against contact along with protected against the effects of continuous immersion in water (IP68).  Table D.3, 2^nd row (copied below), in the IEC 60601-1 standard details all the classifications in a summary list.

Why do we have classifications for protection against harmful ingress of water or particulate matter?

The reason we want to protect the ENCLOSURES of the device is to protect against ingress of these items (liquids and particulates), so they reduce the possibility of causing a hazard, such as a short based on bridging the electronics of the device causing potentially a fire hazard, a shock hazard, a thermal hazard, or other potential hazards.

What are the classifications for methods of sterilization?

For any part of the ME EQUIPMENT or its parts intended to be sterilized needs to be classified per the requirements of sub-clause 6.4. Classifications are based on the types of sterilization methods used in the medical device industry currently such as ethylene oxide (EtO), irradiation by gamma radiation, and moist heat by autoclave. The standard also mentions “…other methods validated and described by the MANUFACTURER.” Classification of sterilization methods is critical because each sterilization method presents unique environmental conditions that can adversely affect the ME EQUIPMENT. For example, EtO Sterilization frequently includes a vacuum cycle which may not be suitable for embedded batteries.

Why do we have a classification for suitability in an oxygen-rich environment?

The RISK of fire in an OXYGEN RICH ENVIRONMENT is considered to exist when a source of ignition is in contact with ignitable material (i.e., flammable materials) and there is no barrier (i.e., a solid enclosure) to prevent the spread of fire.

What are the classifications for modes of operation?

There are two modes of operation described in IEC 60601-1, edition 3.1: 1) CONTINUOUS OPERATION, and 2) non-CONTINUOUS OPERATIONS. When a device is classified as non-CONTINUOUS OPERATION, there is some type of duty cycle involved, so the device is rated properly. A duty cycle means the device is rated to be on for a certain period of time and off for a certain period of time. Many times the duty cycle is required, so a device may pass the EXCESSIVE temperatures in the ME EQUIPMENT test in sub-clauses 11.1.1 & 11.1.2 so as not to exceed the limits of the test requirements.

The Author

If you have questions about this topic or need help with compliance to the IEC 60601 series of Standards, you can email Leo Eisner (the “60601 Guy”) directly at Leo@EisnerSafety.com or call Leo at +1-(503)-244-6151. He is the owner and founder of Eisner Safety Consultants.