Dozens of items have been added to IEC 60601-1 with Version 3.2, recognized by the FDA in August 2020. On December 17, 2023, the new standard version will go into effect. Between Version 3.1 and 3.2, dozens of items were added or modified that were seen as too urgent to wait for the publication of Version 4.
The most substantial changes in Version 3.2 of IEC 60601-1 have been in:
- Clause 2 (Normative References)
- Clause 3 (Terminology & Definitions)
- Clause 7 (Identification and Marking)
- Clause 8 (Protection Against Electrical Hazards)
- Clause 11 (Protection Against Excessive Temperatures and Other Hazards)
- Clause 13 (Hazardous Situations and Fault Conditions)
- Clause 14 (Programmable Electrical Medical Systems (PEMS).
This blog will cover the most major changes made to Clause 8, and what manufacturers should do to prepare their devices that are in development to fit the latest standards.
Main changes to Clause 8 – Protection Against Electrical Hazards
Accessible Parts and Applied Parts
For medical electrical (ME) equipment that has signal input/output (SIP/SOP) connectors or separate power supply output connectors, Clause 8 provides guidance on how to measure the voltage from accessible parts of the connectors that are conductive to the earth.
Based on different conditions, the clause details which currents need to be measured. For example, if the voltage that is measured from the output connector to earth using a resistor and peak voltmeter or oscilloscope is “less than or equal to 60 V d.c. or 42,4 V peak a.c.,” there isn’t a need to do a leakage current test. However, if it is higher, then the touch current also needs to be measured from the supply mains.
Guidance outlined in this area also covers how to measure for normal conditions and single fault conditions, and exceptions for certain conditions where touch current doesn’t need to be measured due to separation devices. Amendment 2 also includes a note about a similar approach detailed in IEC 60950-1:2005, 1.4.9.
Means of Protection
Categorization for Means of Protection (MOP) is related to the ME equipment part or parts being protected from exceeding the permissible limits. A flowchart added as Figure 40 serves as a helpful illustration for how manufacturers can decide what kind of part will be protected by the MOP.
Applied parts or those identified as needing the same requirements as applied parts per 4.6 guidelines are categorized under Means of Patient Protection (MOPP). Outside of that, MOOP and MOPP will be determined by Figure 40 in Clause 188.8.131.52 of Amendment 2.
A note has also been added on coatings and insulation. If these coatings and insulation comply with IEC 60950-1:2005 or IEC 62368-1:2018 and are intended to be used as a MOP, they can be used as a means of operator protection (MOOP) but not automatically a MOPP.
Note 3 has been added to the section about fitting Y capacitors across barriers enforcing the importance of considering the dielectric strength involved. Y capacitors should be chosen based on the voltage peak ranges in a way that meets dielectric strength requirements.
If opto-couplers comply with IEC 60747-5-5-:2007 or later, they are deemed equivalent to:
- 8.8.2 if distances are through solid insulation
- 8.9.3 if insulating compound fills the spaces
Air clearance and creepage distance outside of the opto-coupler, as well as dielectric strength across the opto-coupler, apply. From Clause 3, air clearance is defined as: “shortest path in air between two conductive parts” and creepage distance is the “shortest distance along the surface of the insulating material between two conductive parts.”
The mention of opto-couplers is new in IEC 60601-1 3.2. Previously, opto-couplers did not need to meet IEC requirements.
A note has also been added that testing for distance through insulation (0.4 mm) and thermal cycling are not required because the component compliance “addresses the risk of pin holes and thermal effects on the insulating compound.”
Means of Operator Protection
For solid insulation, creepage distances, protected earthing, and air clearances for means of operator protection, certain insulation coordination requirements need to be met. Version 3.2 cites specific IEC standards for each.
Working voltage measurement
The working voltage for each MOP should be measured by having the circuits connected to the earth. An exception is floating parts that provide at least one MOP to earth, which can be measured by looking at the highest voltage on either side of the barrier. For greater specification, Figure 41 has been added.
Single patient connection
A few mentions throughout the clause have been added about what can be determined as a single patient connection, specifically qualifying applied parts that are all within the body and are in close proximity to one another being treated in this way.
Impedance and current-carrying ability
A detachable power supply cord should be used for testing, and should either be provided by the manufacturer or specified in terms of length and cross-sectional area. Amendment 2 now also includes specification on how the highest-rated current should be determined.
Leakage current, no matter the waveform or frequency, shouldn’t surpass 10 mA r.m.s. In either normal or single fault conditions. This means that either when all means are intact that protect against hazards, or when one abnormal condition or means for reducing risk is defective, the leakage current shouldn’t surpass this value.
Measuring supply circuits
When ME equipment is specified to be connected to a supply mains, it should be connected to an appropriate power source. If the ME equipment is single-phase, supply polarity should be reversible, with tests conducted at both polarities. Figures F.1 to F.5 in Amendment 2 illustrate possible arrangements.
When ME equipment is internally powered, it should be tested without connecting to a measuring supply circuit. However, if this equipment can also connect via a supply mains, it should be tested in the first way as well.
Conductive surface coatings
For coatings that are applied to non-metallic surfaces, they should be done in such a way that if they flake or peel, they won’t reduce creepage distance or air clearance. This can be checked by looking at the construction and data around the construction of the device, or through a coating test standard like ISO 2409 , ISO 4624 , and UL 746C .
RAM Technologies Can Meet Your Medical Device PSU Needs
Manufacturers looking to ready their equipment to meet IEC 60601-1 3.2 requirements can check one item off their list. Our PSUs, built for PC-based medical devices, now meet Version 3.2 requirements. Learn more about PFC800PCX and PFC600PCX, or reach out to us with your questions.