USB port in miniOMNIAlog is not isolated.
For the connection between PC and miniOMNIAlog, SISGEO recommends to use an isolated USB cable:
this is the professional tool to avoid and fight ground loops and equalizing currents and to protect against overvoltage, that could damage miniOMNIAlog or cause flood readings.
Isolated USB cable is especially recommended when the PC and miniOMNIAlog are connected to the main electricity network.