I’ve got 2 Western Digital Element external hard drives. The 1st one is bought from the EU and the 2nd one from the US. As I’m currently living in the EU would it be alright to use the power adapter that came in the box of the EU HDD to power up the American HDD? Could that harm the device since the EU generally operates on a 220-240V, 50Hz electrical system, while the US uses a 110-120V, 60Hz system?
Check what the output on the adaptors are. If they are both, say, 5V 1A DC then you should be fine interchanging them.