The socket with usb charging port is actually equipped with an output DC 5V switching power supply, if there is no total power switch on the socket (strip), then the plug of the strip as long as a 220V power supply is plugged in, the switching power supply will always work, no exception, but the power consumption is slightly smaller than that with load. Although the power consumption of this USB power supply is small, the cumulative consumption is also a lot from day to day, and there is a hidden danger of the original heating, aging and fire. So this kind of socket is not desirable, at least should be installed a power switch, when not in use to turn off.
The usb socket has power, but it's very small,