Let's say that I have a CLASS I EQUIPMENT, with a plastic enclosure and no accessible metal parts.
Reading the 60601-1 it seems to me that, if I don't have any accessible metal parts, the ground bond test is not necessary. Am I correct?
For your equipment to be class I, it has to have accesible or internal parts that are protectively earthed. As yours do not have accessible protectively earthed parts, i'm assuming your equipment has internal parts which are protectively earthed.
The ground bound test verify that protectively earthed parts, accessible or internal, have the right impedance. So, assuming that your have those internal parts, the test has to be done in those parts.
If your equipment do not have protectively earthed parts, it cannot be class I.