A Sixth Sense for a Wired World discusses someone who is experimenting with implanting magnets in their fingers. The purpose is so they can detect electricity and magnetic fields.
I find this a little funny - because I've discovered an innate ability to directly sense electricity, no implanted magnets required.
The ability came as an extension of the high sense perception I use as a healer. Just as I scan a human body for energetic blockages etc, so can I scan wiring looking for which wire is carrying current.
My first experience of this was on a drive across the Mojave Desert. Along the highway there's a power line that's probably one of the main links feeding power to the Los Angeles area. As I drove under the power line I felt a very distinct and palpable presence pass above me. The power line.
Since then it's become more subtle, and I am able to detect slighter currents such as on an alarm clock.