F-type applied part - Separation from ALL(?) other parts

[Benjamin Weber]

Dear community,

I have the following discussion again and again with manufacturers of ME equipment during testing:

Patient connections of F-type applied parts are required to be separated from all other parts by 1 MOPP (60601-1:2012, cl. 8.5.2.1). The question is: Does this relate only to parts of the ME equipment under test or really all other parts, e.g. earth in general?

In my opinion all other parts, not only those of the ME equipment have to be considered. And it is important to focus on the patient connections only during its application on the patient, and not the whole applied part. To me this is even more emphasised by the requirements for patient leads or patient cables (cl. 8.5.2.3).

What is your opinion on this: All parts of the ME equipment or all parts in general?

 

[Benjamin Weber]

Two weeks and 55 views later, really no one has an opinion on this?

 

[Marc]

It happens. I wish there were no unanswered discussion threads here, but I see the same problem in many niche topic forums. Hopefully this "Bump" will help. Unfortunately this is far beyond my field of knowledge.

 

[AbelVV]

Dear community,

I have the following discussion again and again with manufacturers of ME equipment during testing:

Patient connections of F-type applied parts are required to be separated from all other parts by 1 MOPP (60601-1:2012, cl. 8.5.2.1). The question is: Does this relate only to parts of the ME equipment under test or really all other parts, e.g. earth in general?

In my opinion all other parts, not only those of the ME equipment have to be considered. And it is important to focus on the patient connections only during its application on the patient, and not the whole applied part. To me this is even more emphasised by the requirements for patient leads or patient cables (cl. 8.5.2.3).

What is your opinion on this: All parts of the ME equipment or all parts in general?

I don't quite understand the question without context. Is there risk of accidental contact with another part?

 

[Benjamin Weber]

In cl. 8.5.2.1 there is no reference to the risk management, so basically I think that the standard assumes such a risk.

But I can give you an example: The device has F-type applied parts, which are actually metal rods/plates that the patient contacts with his hands and feet (holds in hand or stands on).

The rods and plates are not insulated at all, bare metal. When a patient stands on the plate, the bottom and the sides of the plate could for instance contact other parts below/besides it. When the patient holds the rods in his hands, he could easily contact a grounded radiator with this metal rod.

My question would be: Is it required to protect the metal rods/plates from contacting any other part (like the grounded radiator), or only from other parts of the device itself?

I hope this clarifies my question.

 

[AbelVV]

I understand. I think you should take all possible precautions to avoid contact with unintended objects but ultimately you need an open, conductive surface for the intended use of the product, therefore you can't provide 1 MOPP there.

I'm not an expert, it's just my opinion.

 

[Benjamin Weber]

I understand. I think you should take all possible precautions to avoid contact with unintended objects but ultimately you need an open, conductive surface for the intended use of the product, therefore you can't provide 1 MOPP there.

I'm not an expert, it's just my opinion.

Thank you very much for your thoughts!

In my oppinion it is still possible to achieve 1 MOPP and a conductive surface, as long as we consider the situation when the patient contacts the applied part. The rod and plates should be insulated while only the necessary contact area should be conductive. When the patient contacts the applied part, the conductive area should be completely covered by the patient.

 

[Enternationalist]

In cl. 8.5.2.1 there is no reference to the risk management, so basically I think that the standard assumes such a risk.

But I can give you an example: The device has F-type applied parts, which are actually metal rods/plates that the patient contacts with his hands and feet (holds in hand or stands on).

The rods and plates are not insulated at all, bare metal. When a patient stands on the plate, the bottom and the sides of the plate could for instance contact other parts below/besides it. When the patient holds the rods in his hands, he could easily contact a grounded radiator with this metal rod.

My question would be: Is it required to protect the metal rods/plates from contacting any other part (like the grounded radiator), or only from other parts of the device itself?

I hope this clarifies my question.

The definition of an F-TYPE applied part in 3.29 begins;

"APPLIED PART in which the PATIENT CONNECTIONS are isolated from other parts of the ME EQUIPMENT to such a degree..."

Which I think helps disambiguate the intent of 8.5.2.1 which simply says "all other parts". This seems to me to indicate that the requirements are with respect to the ME EQUIPMENT.

I see it as; F-TYPE parts are meant to help out (basically) in case a patient touches some electrical hazard, and we want our equipment not to have grounded them. It reflects that the equipment floats its PATIENT CONNECTIONS - a classification of the connections' relationship to the equipment - not that its design should attempt to stop all external causes of being grounded.

In my opinion, what you describe is probably something that should be done - but falls into the domain of implementing adequate risk control measures subject to your intended use, not to classifying the nature of your equipment's electrical isolation. (i.e. just because the contacts are large and uncovered, doesn't mean they aren't isolated and floating with respect to the equipment - BUT if we think them being uncovered presents a risk, we'd better do something about it regardless)

 

[Benjamin Weber]

The definition of an F-TYPE applied part in 3.29 begins;

"APPLIED PART in which the PATIENT CONNECTIONS are isolated from other parts of the ME EQUIPMENT to such a degree..."

Which I think helps disambiguate the intent of 8.5.2.1 which simply says "all other parts". This seems to me to indicate that the requirements are with respect to the ME EQUIPMENT.

I see it as; F-TYPE parts are meant to help out (basically) in case a patient touches some electrical hazard, and we want our equipment not to have grounded them. It reflects that the equipment floats its PATIENT CONNECTIONS - a classification of the connections' relationship to the equipment - not that its design should attempt to stop all external causes of being grounded.

In my opinion, what you describe is probably something that should be done - but falls into the domain of implementing adequate risk control measures subject to your intended use, not to classifying the nature of your equipment's electrical isolation. (i.e. just because the contacts are large and uncovered, doesn't mean they aren't isolated and floating with respect to the equipment - BUT if we think them being uncovered presents a risk, we'd better do something about it regardless)

That is actually what was done in that particular situation. I asked the manufacturer to evaluate the risk of contacting other parts (not of the ME equipment). Eventually the resulting risk was unacceptable, thus the contacts had to be isolated as far as possible to still allow the patient contact needed for the intended use.

I really appreciate all of your comments here! It helped me a lot.