Just got an electric blanket having gone without for about a hundred years - it’s winter in Australia at the moment.
The model I got is advertised as having six or so different built in protection mechanisms, so I feel safe with it except…
It’s a double with two separate temperature controllers. If either one side, or both sides are on, anytime my partner and I have slight contact (Jenkins, stop sniggering) we both feel a strange buzzing around the point of contact.
I was going to suggest a couple of things so we could see what’s going on, but they all involve putting yourself at risk by running a current through your body. And really, they would all be in the name of curiosity.
You might have breaks in the insulation connecting you to different circuits so you feel a current flowing between you. But this seems unlikely because as long as there are not many long uninsulated sections of wire touching your bare skin, there wouldn’t often be a connection.
Perhaps they use a high frequency power control method, some kind of pulse width modulation, and there’s enough capacitive coupling to your bodies that you can feel it. They might distribute load between the two halves of the blanket by alternating which one of you is powered up. Though, this idea seems a bit far fetched, too.
I’m a little mystified how you’re feeling anything, but believe that you do - the way you describe it is distinctive enough that it sounds right. Odd. I wouldn’t trust it.
I have one of these dual electric blankets, and it does not do that with two people sleeping with it on. No buzzing at all. Take it back for replacement and/or call the manufacturer.