MOOP and insulation coordination



IEC 60601-1 clause states that solid insulation shall comply with the dielectric strength test OR comply with insulation coordination requirements per IEC 60664-4 (not per IEC 60950-1 as printed).

I find IEC 60664-4 is very difficult to understand so could anyone summarise the requirements which must be complied with in order to avoid performing dielectric strength tests.


Doug (aka petruchio)
Cambridge UK

Peter Selvey

Super Moderator
The standard refers to IEC 60950, not IEC 60664-1.

In principle the standard is saying that the designer can choose to comply with the requirements in IEC 60601-1 or IEC 60950 for operator parts.

This is a major change in the 3rd edition, and is intended to allow the use of cheaper parts such as 950 power supplies to be used in medical equipment, as long as the insulation only affects the operator, not the patient.

In practice, the designer can select a 950 certified part, which would allow them to skip 601 assessment. If the part is not certified to 950, then it makes sense to test according to 601. The requirements in 601 for operator protection are mostly harmonized with 950, logistically it makes sense to use 601 requirements for uncertified parts, rather than trying to work with 2 standards for no benefit.
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