APPENDIX A: IEC 601.1, UL 2601.1 AND VDE 0751
TESTING
This appendix describes International Electrotechnical Committee (IEC) Standard 601.1, Underwriters
Laboratories (UL) Standard 2601.1, and Verband Deutscher Elektrotechniker e.V. (VDE) 0751 Stan-
dard tests, their functions, applicability, and equipment connections.
A.1 Classification of Equipment
Electrical safety begins with considering the mains electricity supply, and how to feed that into an item
of equipment so that it is able to power the electronics internally and, at the same time, ensure that there
is no possibility of the mains power coming into contact with either the patient, user or a third person.
The classification of equipment under
IEC 601.1 and UL 2601.1 describe how the mains part insulation
is achieved. The techniques used include: air clearance; insulating materials (basic or functional insula-
tion); creepage distances, and; double insulation
1. Class 0. The mains part is completely separated from any of the accessible parts. The separation is
achieved by basic insulation. This is not
used in medical applications.
2. Class 1. In addition to the basic insulation, there is protection via the protective earth conductor in
the mains lead. This is intended to connect all the equipment’s accessible parts to earth. The major-
ity of electromedical equipment is Class 1 equipment.
3. Class 2. Equipment of this class is constructed with double insulation, i.e., two distinct insulating
layers around the mains part. The purpose is that, should the basic insulation of the mains part fail,
and then a second insulating barrier exists to prevent the mains from coming into contact with the
user or patient. (See illustration below.)
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