Re: 5v/12v ring
Agreed, but wondering what the load would actually look like though, I'm envisaging a low-power type socket, I wouldn't imagine anything heavy watts on it. Think about all the wall warts around your house, they're typically a couple of watts at 5V only, maybe 12V and 50W or something for a laptop, but nothing like the 300W you suggest. LED lights are single watt too.
House of the future, outside the kitchen I can't think of more than 5 appliances that would use more than 10W. It would also eliminate the risk of the 20 to 30 transformers around the house (some built into power sockets already) of varying quality and fire safety. I'm thinking of one certified transformer in the consumer unit instead that takes care of everything, with RCD built in. Presumably more efficient than the multiple cheap nasty things at each socket too.
Biting the hand that feeds IT
