Sadly wrote:
I seem to remember seeing a device that you plug in to a 3-pin socket
and you then plug in two appliences - when one draws power it switches
on the other. I have seen them used to turn on a vacuum cleaner when a
power tool is used (so it only socks the dust when required).

What are these called, and where can I get one?


These are sold in Lidl from time to time for about £15. I have one to
power on peripherals when I turn my PC on.
http://www.iomai.de/uk/masterslave.html

Never seen a UK firm selling them

john2