I found one of my little magnets stuck to my USB to micro USB phone charging cable. I thought this was a bit odd, since cables usually have copper wire or sometimes aluminum shielding. Why put a magnetic iron wire in a cable?
This was the only cable they stuck to, other cables were nonmagnetic. Very curious.
Because steel is cheaper than copper. See: http://hydraraptor.blogspot.com/2016/04/beware-fake-wire.html
Apparently steel in cheap wire is not uncommon.
Thenk you for the heads up. I’ve also found undersized wire in power cords. That can lead to a fire. As for the USB cable, if the two wires for the data are not pure copper, it’s not so important because the current is low and high frequency signals propagate through the skin, not the center of the conductor. As a matter of fact, many of the coaxial cables have a copper coated steel conductor for strength. But if the two power wires are not copper, then if someone tries to use it for charging, the wire could overheat.
I also have noticed that the cheap wire often has extra thick insulation to make it look thicker than it really is. In my case, I have not noticed the wire getting warm. I think I will be taking a magnet with me to the computer store and use it to check when I buy cables next time.