Class II symbol - where to apply it?


Involved In Discussions
ME EQUIPMENT is constituted by a Main Unit and a Class I AC/DC converter (thus the AC/DC has a PROTECTIVE EARTH), medical grade (2xMOPP, Type BF compliant output). The AC/DC is considered part of teh MEE according to MEE is Class II.

Intended environment is the Professional Healthcare Environment, thus PROTECTIVELY EARTHED outlets are assumed.

According to subclause 7.2.6, for CLASS II ME EQUIPMENT, symbol IEC 60417-5172 (see Table D.1, symbol 9) should be added;

... these markings shall appear on the outside of the part that contains the SUPPLY MAINS connection and preferably adjacent to the connection point

All the other markings required by a Class I device are on the label of the AC/DC converter.

I would like to avoid making any modification on the AC/DC converter even if involves only attaching a self-adhesive label with the symbol. Would it be OK using the symbol on the label of the Main Unit instead? From a risk management perspective, I do not see any risk on this approach, but I would like to have a second (or third etc.) opinion on this.

Peter Selvey

Super Moderator
Do not put a Class II symbol on the ac/dc converter, this would be illegal and serious degree of liability in case anything went wrong. The labelling on the adaptor MUST NOT be modified in any way.

There are two ways to view this combination:

a) The converter and main unit are a set and form one "device" or one item of "MEE" according to the standard. In this case the set it is Class I (as determined by the converter, since it connects to mains supply). No marking of Class II is needed.

b) the converter and main unit are considered two separate MEE, which together form a ME system. The converter is Class I and the main unit is Class II. However, marking for Class II is only required for MEE that connects directly to the mains supply (i.e. the 230V or 100V coming from the wall). Since the main unit does not connect to the mains supply, no marking of Class II is needed.

So, in both case, no Class II symbol should appear on either device (converter or main unit). Note this is commonly misunderstood and many test labs ask for a Class II symbol to be put on the main unit even though it does not connect directly to the mains supply.
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