What is the function of the Critical Component List?


Involved In Discussions
What is the function of the critical component list? How does it serve in different departments?

Is it a requirement coming from the ER? Or the CB testing and hence 60601-1? I couldn't find any good information in 60601-1. Can someone point me to the right standard or in the reight direction?

Mark Meer

Trusted Information Resource
Good question. I've wondered the same. Though not explicitly in the 60601-1 standard, all CB test reports have the list.

Which leads me to believe it has something to do with the CB scheme or NRTL certification - its purpose being strictly for inspections. It is a convenient "short list" of the most important components that certification bodies can use to confirm production controls are adequately maintained during their surveillance inspections.

I may be wrong, but this appears to be its use in practice.

Peter Selvey

Super Moderator
There are three drivers for the list:

One is a basic ISO 17025 requirement that the test records have enough detail to be able to re-produce the result (e.g. if challenged, or design update etc). This is done through identifying manufacturer, make/model, serial number, photos and critical parts list, circuit diagrams, spec sheets for certain parts and so on.

The second is that IEC standards normally have a clause that requires certain parts to be certified components, and some clauses also make reference to specific attributes. A list of critical components helps to provide evidence of meeting these requirements (in the body of the report, you can just say, see the critical component list, rather than listing each part in the relevant clause).

The third is that if product certification is involved, the factory inspectors will use this list (and the photos, spec sheets etc) to confirm the product has not changed. The most popular by far is NRTL but there are other schemes.

None of this should imply parts listed are special in the sense only changes to those parts trigger retesting or evaluation.

Regardless of what is on the list, for the manufacturer any design change should trigger at least an internal re-evaluation of standards compliance, which might range from a single sentence - "obviously no effect" - through to detailed re-testing.

If the device is under product certification, a separate decision has to be made whether to report the change to the agency. The list might influence the decision, but keep in mind other changes can also trigger re-evaluation (for example, a software change or "non-critical" secondary part change might influence transformer loading).

For CB reports, there is no obligation to report changes. CB reports are only a stepping stone to product certification. They keep the lists also with an eye to facilitate the eventual certification process/factory inspections. But strictly speaking this is not the real list used for product certification.
Top Bottom