For what it's worth

Manufacturers seem very coy to admit that their Mains-socket-with-built-in-USB-power will consume power all the time, even when the mains sockets are off and nothing is plugged in. I couldn't find any indication in published specifications.

(Does any company make a socket with zero consumption when idle? I suspect not, but would be delighted to discover that I am wrong).

For the socket that I was considering (made by BG - Technical Data document here), there was nothing about consumption, so I asked the manufacturers.

All credit to them, the replied within hours, to say 75 milliwatts. Multiply that by 8760 hours/year and you get 0.66 of a kwh per year. 

Perhaps a consideration if you are planning lots of USB mains sockets, but for one or two in a house, the waste is small compared to the many other ways we waste power.

# posted by John Geddes @ 3:55 pm