I got a string of LED Xmas lights hung behind my TV connected with an extension cord. I want to buy a power bar with a switch to turn it off but for now, I just unplug the strand from the extension cord and to keep the extension plug from falling I plug the lights using only one prong leaving the other open. At first, I thought it was just a reflection but in complete darkness and with my hand cupped, I can see all the LEDs are lit. Not much but you can easily tell that they are on.
For this to work a 120v to 9v DC plug in block adapter is plugged in to the string at the other end. But that doesn't get power either as it is dependent on the power coming from the string of lights.
So why is the string of lights powered with 1 prong of the plug disconnected?