"Leak" is a hard requirement. All electrical appliances have to "leak". Most people don't understand circuits. In fact, this leakage is deliberately designed by the circuit.

In fact, this kind of "leakage" electrical appliances are all switching power supplies. Switching power supply is divided into high voltage end and low voltage end. The high-voltage terminal is 220V, and the low-voltage terminal is to change the voltage of 220V into the voltage actually used by circuits such as 12V and 5V. Moreover, the negative electrode of the low-voltage terminal is usually grounded, which is actually connected to a metal shell or a large-area bottom plate. Switching power supply needs a high resistance to connect the high-voltage terminal and the low-voltage terminal, usually several hundred K. This is to prevent the circuit from electrostatic breakdown and let the charge leak through a channel. Without this resistor, static electricity may accumulate, leading to extremely high voltage and breakdown of isolation transformer. However, this design is usually safe, and the leakage current should be small enough not to cause harm to human body. But in fact, many electrical appliances will have numbness. In fact, this leakage current is a bit large. Typical is the desktop, there is no metal shell that does not leak electricity. Of course, you may say that most of the time it is not electrified because of the grounding design. As long as there is a ground wire in the three-terminal jack, the leakage current will not feel anything.