External PSU Providing a MOOP -- Will This Necessitate Conducted Emissions Testing?

[WalkerNelson678]

Hello All,

At my company, we are developing a low-risk "wearable" medical device. The device is accompanied by a wireless charging pad, which is the subject of my question.

The charging pad is rated for 5V 0.5A DC input, and therefore we are claiming that it is NOT a mains part. However, the most obvious use case is that the operator plugs the pad into a phone charger to supply power.

After discussion (and a previous post here) we have convinced ourselves of, and have high confidence in, the decision that that safety testing applicable to mains connected parts (one example is 60601-1-2 -- section 8.9 -- table 5, although there are others from 60601-1 itself) will not apply to us. Mainly this is for two reasons:

1. We do not manufacture the USB power supply
2. We state in the user manual that only the use of a power supply conforming with IEC 62368-1 is acceptable

As I said, we are feeling pretty confident in this decision.

However, we are getting some pushback from consultants / test labs to consider using the IEC 6238-1 power supply as a MOOP for the charger pad. This is acceptable according to 60601-1 clause 8.5.1.3 with the caveat that the power supply only constitute one MOOP (to the best of my knowledge).

Although this action is technically allowable, I worry that by including the power supply as a MOOP, we open the door for an FDA reviewer to question our exemption from the aforementioned "mains part" tests. I am thinking that if we use the PSU as a MOOP, a reviewer could claim that it is part of our equipment, and therefore will requires us to go back and retest for all of the AC power port tests which we originally exempted ourselves from.

So finally, my question:

Are these two concepts/statements mutually exclusive in 60601?

1. My device is usable with any 62368-1 PSU which supplies 5V 0.5A DC, therefore, the PSU is not part of my equipment and I should not have to perform tests which are required for a mains part (again, such as 60601-1-2 section 8.9, table 5).
2. A 62368-1 compliant PSU forms one of the MOOPs for my device

Please let me know what you think. Am correct in thinking that making both of these claims simultaneously is a potential regulatory risk? Or is this simply something that I am overthinking for a low-risk device and that a reviewer is not likely to care about.

Thanks,
~Walker

 

[Peter Selvey]

A little legalistic background here.

The FDA, like other regulations, makes use of a "declaration of conformity". This is a formal document according to IEC/ISO 17050-1 and IEC 17050-2. A declaration of conformity is not only a statement that an object conforms to the standards, but also identifies the entity "responsible" for conformity as well as "continuing validity" of conformity. In a regulatory/legal context, a declaration of conformity is not for samples tested, but for the objects that are actually placed on the market.

Equally, a "type test" is a special kind of test which is intended to be representative of regular production. A declaration of conformity often refers to a "type test" as evidence. A type test is only valid if the manufacturer (responsible entity) has controls in place to ensure that tests on a sample are in fact representative of regular production.

The upshot here is that it is impractical to have a "type test" or "declaration of conformity" on a system that is made up of devices from different manufacturers.

Unfortunately, not many people are familiar with the distinction of "test" vs "type test", or that a "declaration of conformity" is much more than meets the eye. The FDA is pretty bad for this point as well, some of their guidance documents directly contradict this, for example recommending EMC tests on systems made up of devices from different manufacturers. Test labs are taught to test and report on the sample supplied (which could be a system of several devices), and their thinking usually stops there. Consultants often come from test labs. IEC 60601-1 itself also has some issues, such as how it handles ME systems.

Anyway: testing your device with the PSU is meaningless. It does not matter what the consultant says. It would be an illegal, false claim in the "declaration of conformity" in the FDA submission.

Now, Clause 8.5.1.3: this clause seems to be quoted out of context, it is part of the overall system in 8.5 which gives various options to the designer of the ME equipment, but does not apply to an ME system.

For a separate power supply, see:
4.10.1
5.5 f)
7.9.2.3
8.2.1

The most important clause is 8.2.1, which directly allows a generic PSU to be used.

According to that clause, the combination is a ME system, and Clause 16 is required.

However, in practice, there is nothing in Clause 16 which is applicable in this case, because the Clause 16 is focused on the "patient environment". In your set up, there is no patient environment when the device is charging. Outside the patient environment, normal safety applies, which means that IEC 62368-1 is OK. There are some applicable requirements in Clause 16.2 for the IFU, but these are also effectively covered by 8.2.1.