IEC 60601-1:2005/ISH3:2013

SC 62A/Publication IEC 60601-1:2005, including Amendment 1:2012, Third edition/I-SH 03
MEDICAL ELECTRICAL EQUIPMENT –
Part 1: General requirements for basic safety and essential performance

INTERPRETATION SHEET 3
This interpretation sheet has been prepared by subcommittee 62A: Common aspects of
electrical equipment used in medical practice, of IEC technical committee 62: Electrical
equipment in medical practice.
The text of this interpretation sheet is based on the following documents:
ISH Report on voting
62A/858/ISH 62A/875/RVD
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.
___________
Subclause 13.1.2 fourth dash (Emissions, deformation of ENCLOSURE or exceeding
maximum temperature)
This subclause states the following:
The following HAZARDOUS SITUATIONS shall not occur:
− ….
− temperatures of ME EQUIPMENT parts that are not APPLIED PARTS but are likely to be
touched, exceeding the allowable values in Table 23 when measured and adjusted as
described in 11.1.3;
This is clarified by the following:
The above requirement is regarded as fulfilled in accordance with Subclause 4.5 for
temperatures at the surfaces of the enclosure, if the following conditions are fulfilled:
− The maximum allowed temperature on OPERATOR accessible surfaces in SINGLE FAULT
CONDITION is 105 °C; and
− the instructions for use contain a warning that, under some SINGLE FAULT CONDITIONS, the
temperature of: (indicate the surface of concern) could get hot and there is a possible RISK
of a burn if touched, and
− if the RISK ANALYSIS demonstrates a need for a warning symbol on the ENCLOSURE, safety
sign ISO 7010-W018 ( ) shall be used on or adjacent to the hot spot on the
ENCLOSURE; and
− the RISK ASSESSMENT demonstrates that the temperature attained in the SINGLE FAULT
CONDITION is acceptable, and
− the RISK ASSESSMENT demonstrates that applying the alternative RISK CONTROL measures
in this Interpretation Sheet results in a RESIDUAL RISK that is comparable to the RESIDUAL
RISK resulting from applying the requirement of the standard.
NOTE 1 This Interpretation Sheet is intended to be used with both Edition 3.0 and Edition 3.1 of IEC 60601-1.
NOTE 2 An example of an analysis that demonstrates an adequately low probability of occurrence of HARM is
shown below.
May 2013 ICS 11.040 French text overleaf

Example RISK ASSESSMENT:
The sum failure rate for parts that could increase the surface temperature of parts of the
enclosure of XYZ device touchable only by the OPERATOR to values above those of Table 23
calculates to be 60 FIT (1 FIT = 1E-9/h) according to the standard MIL-HDBK-217F where FIT
stands for "failure in time". In case of such failures, the device would emit an odour and would
no longer function properly. It is estimated, that only in one of 3 cases the device would not
be switched off immediately and the hot surface would be resulting in a burn.
The resulting overall probability of such HARM where adequate warning is provided in the
instructions for use in combination with warning sign ISO 7010 W018 would be: probability
= 1/3 * 60 FIT = 2 E-8/h =approx. 0,0002 per year.
In this example, the WXW Company's RISK acceptance criteria require that a HARM of that
severity must have a probability of less than 0,0003 per year for the associated RISK to be
considered acceptable. Based on that RISK acceptance criterion, the RISK associated with
overtemperature of the ENCLOSURE caused by single faults in the circuitry is acceptable.

May 2013 ICS 11.040 French text overleaf

SC 62A/Publication CEI 60601-1:2005, y inclus l'Amendement 1:2012,
Troisième édition/I-SH 03
APPAREILS ÉLECTROMÉDICAUX –
Partie 1: Exigences générales pour la sécurité
de base et les performances essentielles

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