Leakage current tests for battery powered device with IEC 62368 compliant charger

[standardnovice]

Hi, this is my first post here and I'd like to say what a great resource this forum has been for me as i am very new to regulatory work in my firm.

I have the following conundrum:

I have a battery powered (internally powdered) medical device that can connect to
1. A battery charger compliant with IEC 62368 that is connected to mains
2. Other equipments that are connected to mains which are IEC 60601-1 or IEC 62368 compliant, used to transfer signals to my device.

Q: Do I have to consider earth/touch leakage current from the above 2 when my device is connected to them?

Example- current flowing through the medical device to the patient (via other contacts) to the ground? Especially given the compliance of charger/equipment to 62368 or 60601?

Note: If leakage current tests do apply, could you clarify if they follow clause 8.7 or 16.6 (ME equipment or ME system) when these equipment are connected to my device.

Thank you in advance!

 

[Peter Selvey]

Any parts of a "ME system" within the "patient environment" (a defined term) should comply with the earth/touch leakage current limits in IEC 60601-1 even if a equipment is already certified to the relevant standards. A system can consist of a medical device powered by a non-medical device, signal connections to other non-medical equipment and the use of multi-socket powerboards which then power multiple items of equipment both medical and non-medical. This is all covered by Clause 16.

However there are a few non-intuitive concepts. First any certified equipment (medical or non-medical) should not be modified in anyway that requires a tool or obscures the original labelling.

Second, if the system as set up initially "fails" the leakage current limits, then you can select different options to get below the limits. Options are additional earthing (to divert the currents), mains isolation transformers, separation devices (external or built into the medical device), instructions to keep certain items outside of the patient environment, instructions not to use power boards. Also in the case of a IEC62368 power supply there is an option to deliberately select a model that has known earth/touch leakage, which is probably the simplest option.

In reality, this issue is more of a technicality and it only with very special situations where it is important to keep within the 601-1 limits, things like surgeries, intensive care, dialysis. A common implementation allowed by most test labs would be to use a IEC62368 power supply that is within earth/touch limits, and then use a warning that when making signal connection or using powerboards follow IEC 60601-1 Clause 16, then leave it to the user to implement, which they rarely do, but again it's not critical. A test lab can usually provide a text warning they consider acceptable.

 

[standardnovice]

Any parts of a "ME system" within the "patient environment" (a defined term) should comply with the earth/touch leakage current limits in IEC 60601-1 even if a equipment is already certified to the relevant standards. A system can consist of a medical device powered by a non-medical device, signal connections to other non-medical equipment and the use of multi-socket powerboards which then power multiple items of equipment both medical and non-medical. This is all covered by Clause 16.

However there are a few non-intuitive concepts. First any certified equipment (medical or non-medical) should not be modified in anyway that requires a tool or obscures the original labelling.

Second, if the system as set up initially "fails" the leakage current limits, then you can select different options to get below the limits. Options are additional earthing (to divert the currents), mains isolation transformers, separation devices (external or built into the medical device), instructions to keep certain items outside of the patient environment, instructions not to use power boards. Also in the case of a IEC62368 power supply there is an option to deliberately select a model that has known earth/touch leakage, which is probably the simplest option.

In reality, this issue is more of a technicality and it only with very special situations where it is important to keep within the 601-1 limits, things like surgeries, intensive care, dialysis. A common implementation allowed by most test labs would be to use a IEC62368 power supply that is within earth/touch limits, and then use a warning that when making signal connection or using powerboards follow IEC 60601-1 Clause 16, then leave it to the user to implement, which they rarely do, but again it's not critical. A test lab can usually provide a text warning they consider acceptable.

Thank you for your extremely valuable input, Peter!

If I understand correctly - the leakage requirements come into the picture as a part of ME System requirements of Clause 16.

However, since my device is a battery powered device that can connect to a power supply(charger) or to other mains powered equipment for SIP/SIO, I am a bit confused about how to test leakage requirements when it comes to clause 8.7

Specifically 8.7.4.2 - Note 2:
"For INTERNALLY POWERED ME EQUIPMENT, Figure 14 to Figure 20 (inclusive) do not use the isolation
transformers T1 or switches S1 and S5. However, INTERNALLY POWERED ME EQUIPMENT that also has a means of
connection to a SUPPLY MAINS shall also be tested according to a) above for that connection."

Q: I am unsure whether I must perform leakage tests with mains voltage (using isolation transformer), or simply with my device's battery voltage.

Especially, in case of touch current which states in 8.7.4.6 a) - " INTERNALLY POWERED ME EQUIPMENT is investigated for TOUCH CURRENT but only between parts of the ENCLOSURE, not between the ENCLOSURE and earth unless 8.7.4.6 c) applies."

I hope this is not too loaded a question. Apologies if this is the case.
Thank you again!

 

[dnyberg2]

Any parts of a "ME system" within the "patient environment" (a defined term) should comply with the earth/touch leakage current limits in IEC 60601-1 even if a equipment is already certified to the relevant standards. A system can consist of a medical device powered by a non-medical device, signal connections to other non-medical equipment and the use of multi-socket powerboards which then power multiple items of equipment both medical and non-medical. This is all covered by Clause 16.

However there are a few non-intuitive concepts. First any certified equipment (medical or non-medical) should not be modified in anyway that requires a tool or obscures the original labelling.

Second, if the system as set up initially "fails" the leakage current limits, then you can select different options to get below the limits. Options are additional earthing (to divert the currents), mains isolation transformers, separation devices (external or built into the medical device), instructions to keep certain items outside of the patient environment, instructions not to use power boards. Also in the case of a IEC62368 power supply there is an option to deliberately select a model that has known earth/touch leakage, which is probably the simplest option.

In reality, this issue is more of a technicality and it only with very special situations where it is important to keep within the 601-1 limits, things like surgeries, intensive care, dialysis. A common implementation allowed by most test labs would be to use a IEC62368 power supply that is within earth/touch limits, and then use a warning that when making signal connection or using powerboards follow IEC 60601-1 Clause 16, then leave it to the user to implement, which they rarely do, but again it's not critical. A test lab can usually provide a text warning they consider acceptable.

Peter, I wanted to ask you a question about another topic on electrocautery but cannot seem to send you a private message. Can you please reach out to me directly so I can ask your opinion on that topic? Dave Nyberg [email protected]