Friday, August 19, 2022

IEC 60601-1 Creepage Distance and Air Clearance

Hi friends!!!

In our previous blogs, we have discussed about the following topics.

IEC 60601-1 Definitions

IEC 60601-1 Classification of Medical Electrical Equipment

IEC 60601-1 General Requirements for Testing Medical Electrical Equipment

IEC 60601-1 Medical Electrical Systems

IEC 60601-1 Protection against unwanted and excessive radiation hazards

IEC 60601-1 General Requirements

IEC 60601-1 Programmable Electrical Medical Systems 

IEC 60601-1 Hazardous situations and fault condition

IEC 60601-1 Construction of Medical Electrical Equipment

IEC 60601-1 Leakage Currents and Patient Auxiliary Currents

EU MDR Assessment Routes

EU MDR Timeline, Annex, Chapter

EU MDR Post Market Surveillance

EU MDR Clinical Evaluation

EU MDR Technical Documentation - Part 1

EU MDR Technical Documentation - Part 2

EU MDR General Safety and Performance Requirement

EU MDR Information on the Label

EU MDR Post Market Clinical Follow Up

EU MDR Unique Device Identification - Part 1 

EU MDR Unique Device Identification - Part 2

EU MDR Classification Rules


EU MDR Economic Operators

EU MDR Chapter & Articles - Part 1

EU MDR Chapter & Articles - Part 2

In today's blog, we are going to discuss about IEC 60601-1.

IEC 60601-1 states the Basic safety requirements for Medical Electrical Equipment's. Satisfying the requirements of IEC 60601-1 is an important task in order to commercialize the Medical Electrical Equipment's

Therefore, it is important for Medical Device QA/RA Professionals to know in detail about Sub Clause 8.9: Creepage Distances and Air Clearances as per IEC 60601-1.

Let's get into the topic.

Sub Clause 8.9: Creepage Distances and Air



The Sub Clause 8.9 of IEC 60601-1 states the requirements for Creepage Distances and Air Clearances.


Let’s discuss in detail about the important requirements of above-mentioned Sub Clause.


Creepage Distance:


The Creepage Distance is the shortest distance between the two conductors along the insulating surface. The Creepage Distance must be greater than or equal to the Air Clearance.


Air Clearance:


Air Clearance is the Shortest Air path between two conductors.


The Creepage Distance & Air Clearance shall be derived from Table 12 – Table 16 in IEC 60601-1. If the Creepage Distance value is less than the values of Air Clearance, then the value of Creepage Distance shall be considered same as the Value of Air Clearance. The following are the overview of information provided in Table 12 -Table 16 of IEC 60601-1.


Table 12:


In Table 12, the Minimum Creepage Distance and Air Clearance Values can be derived based on d.c. & r.m.s. working Voltages for One Means of Patient Protection and Two Means of Patient Protection.


Table 13:


In Table 13, the Minimum Air Clearance Values providing Means of Operator Protection from Mains Part shall be derived based on Nominal Mains Voltage & Working Voltage.


Table 14:


In Table 14, additional Air Clearance values for Insulation in Mains Part shall be derived for Peak Working Voltage exceeding the Peak Value of Nominal Mains Voltage.


Table 15:


In Table 15, Minimum Air Clearance Values providing Means of Operator Protection in Secondary Circuit shall be derived based on Transient Value for Secondary Circuit & Working Voltage.


Table 16:


In Table 16, Minimum Creepage Distance Values providing Means of Operator Protection shall be derived based on Pollution Degree and Working Voltages.




The following conditions determine the Creepage Distance and Air Clearance:


Input Voltage.


Material Group.

Pollution Degree.

Overvoltage Category.



Let’s see in detail about some important above-mentioned conditions which determine the Creepage Distance & Air Clearance.


Material Group Classification:


The Material Group Classification is based on Comparative Tracking Index (CTI). The Electrical Breakdown properties of an Insulating Material is measured using CTI.


The Table 9 of IEC 60601-1 represents the Material Group Classification as Material Group 1, Material Group II, Material Group IIIa & IIIb Based on CTI Criteria.


If a Material Group for Insulating Material is unknown, then Material Group IIIb shall be considered.


Pollution Degree Classification:


The Pollution Degree is classified as Pollution Degree 1, Pollution Degree 2, Pollution Degree 3, Pollution Degree 4.


Pollution Degree 1:

The Pollution Degree I means Micro-Environment that is sealed, No Pollution Occurs.


Pollution Degree 2:

The Pollution Degree 2 means, occurrence of only Non-Conductive Pollution.


Pollution Degree 3:

The Pollution Degree 3 means, occurrence of Conductive Pollution or Dry Non-Conductive Pollution due to expected condensation.


Pollution Degree 4:

The Pollution Degree 4 means, occurrence of Continuous Conductivity due to conductive dust, rain and other wet conditions.


Overvoltage Category:


The Mains Transient Voltage value shall be determined based on the Overvoltage Category according to Normal AC Mains specified in Table 10 of IEC 60601-1.




The Medical Electrical Equipment shall be rated to operate at an altitude of Less than or equal to 2000m, unless specified by the manufacturer. If the Medical Electrical Equipment is intended to be operated in Pressurized Environment, then the Operating Altitude corresponding to the air pressure of the environment shall be used to determine the Multiplication factor based on Table 8 of IEC 60601-1. This Multiplication factor shall be used in Calculating the Air Clearance value.

Now I hope you have acquired some knowledge about IEC 60601-1 Sub Clause 8.9: Creepage Distances and Air Clearances. We will meet again with another valuable topic related to Biomedical Engineering, Medical Device, Healthcare.

NOTE: Dear friends!!!... Please do comment a topic related to Biomedical, so that we can discuss it in future blogs.

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