The magnetic field is mostly confined to the core of the transformers, so your power supply isn't going to start attracting things like a giant magnet. This int

The magnetic field is mostly confined to the core of the transformers, so your power supply isn't going to start attracting things like a giant magnet. This internal field is pretty strong, though, up to 0.3 Tesla in a ferrite core. In comparison, a refrigerator magnet is 5 millitesla and the Earth's magnetic field is 30 microtesla.