Components and Approvals
developer of an electrical medical device, you will probably use components manufactured by other companies. Those components, which may influence the safety of your product,
are known as safety critical; when you submit your product to a laboratory for testing to IEC 60601-1, the test engineer will want to have proof of the compliance of these components.
All components carrying mains voltage are considered safety critical. Such components include: mains transformers, mains switches, fuses, fuseholders, appliance inlets, EMI
Other components having a specific safety function are also
considered safety critical, e.g. thermoswitches, optocouplers, interlock switches, etc. Battery charging
circuits are also considered safety critical.
It is generally in your interest to use components which already have approvals to North American (e.g. UL, CSA) and European
(e.g. TUV, VDE, Demko, etc.) test houses. In most cases you should ask the component manufacturer for a copy of the component approval certificate. The engineer who tests your product
will ask to see this.
Be wary of component manufacturers' use of phrases such as 'conforms to', 'compliant with' or 'designed to'. This usually means that there is no
third party approval of the component.
There may be situations where you cannot find a suitable approved component. In this case you will have to bear the cost of testing the
component within the framwork of your product's approval. You will also have to ensure, by means of a written agreement, that the manufacturer does not change the component or any of
the materials used in it without your knowledge. This situation may arise for isolation transformers. It is unlikely to occur for other components such as switches, fuses, etc.