This, however, is not just any plug. Designed by the Dutch electronics giant Philips, it is able to send and receive data over the mains network, meaning that it can communicate between microprocessors in appliances such as washing machines and computers.
The "home appliance modem" has been taken up by a French company, which is using it in window shutters which can be electrically operated opened or closed from any part of the house.
But Philips anticipates that the modem, similar to that already used by computers, will be incorporated into a much wider range of appliances within a few years. "It can both send and receive information - both are built into the chip," said Jonathan Woodcock, a marketing director at Philips.
The modem communicates by adding high-frequency signals, just 1 volt in strength, to the existing mains voltage - 240 volts in Britain. A growing number of modern home appliances, including VCRs, TVs, dishwashers, cookers, burglar alarms and central heating systems are built around microprocessors. By enabling these to send and receive data over their mains cable, the homeowner would be able, for example, to set the dishwasher running and turn the oven on, with instructions punched in from a mobile phone while on the way home.
Security could be ensured by giving every home's system a PIN code, as used for bank cards. And there would be no risk that signals sent around one person's home might travel over the mains to switch on the oven in their neighbour's house: as Mr Woodcock explained: "Every mains source has a large coil, used to measure the flow - and that... acts to stop the signal passing beyond that point.Reuse content