AC causes radio emissions (which is lost power), it doesn't affect the magnetic field unless it forms coils. And most coils on AC will be put into iron cores to

AC causes radio emissions (which is lost power), it doesn't affect the magnetic field unless it forms coils. And most coils on AC will be put into iron cores to contain them nice and close to where they belong. Even then an AC coil doesn't really behave magnetic very much since the field reverses polarity so often. A DC wire will constantly produce a static magnetic field. With only a few kilowatts, you can probably measurably shift a compass needle within your house, since all your wires will necessarily have to form a loop (positive and ground). Magnetic fields aren't created by shifting the DC voltage or current, they're created by current flowing through a wire, AC just has the advantage that 20ms later, the field goes the other direction so few things care. What will happen when DC load shifts is that the magnetic field changes and it'll dissipate or absorb power from the DC line to do so (Relays require you to put in a diode so that when they are switched off, they can dissipate the stored field energy safely without damaging electronics. This dissipation happens at much higher voltage levels than what induced it and is of opposite polarity to your input voltage.