According to a report carried out in news.com.au, the new device, made by Australian firm ETSA, would go in the meter box and remotely read meters, turn power on and off, report outages - and, if the customer agreed, ration power to an individual home.

It is controlled by an FM radio signal and on a house-by-house basis.

ETSA chief executive Lew Owens said that the new device, now being trialled, could prevent the kind of load-shedding blackouts across entire suburbs that Adelaide experienced in January, by reducing demand across the city.

ETSA wants to introduce the system some time after 2010 and could eventually roll it out into all homes in Adelaide.

It follows the successful trial by ETSA of a less sophisticated "peak breaker" box attached to air conditioners in Mawson Lakes and Glenelg, which was used to turn off refrigerated air conditioner compressors in periods of peak demand during heat waves.

"We can turn off the compressors and leave the fan circulating the air," said Owens. "We turn it off 15 minutes in every hour by an FM radio signal and the customer doesn't know it's happened," he added.

The trials found that peak electricity demand during heatwaves could be reduced dramatically by the control boxes, with Mawson Lakes homes' power consumption cut by about a third, and Glenelg's by about 20 per cent.

Owens emphasised that while ETSA planned to put the new boxes in all homes, customers would choose whether to allow it to be used to ration power.

However, he added that people who did not take this option might find they would lose all power when power demand was running at peak levels.

According to ETSA, the box is sophisticated enough to control specific equipment in the home