Given that IEC 60601-1 clause 8.6.4 only permits 100 mili ohms unless the device has circuits that limit the current to maintain the required touch current limits.
So, refer to the device instructions for use to see if another value is permitted, but consider the issue of the wrong cable being used with a device that it is not intended for!
For non-medical devices EN 50699 has values for longer cables.
