Electricity Meter

You talking 'electro-mechanical' or 'electronic'?

Seen quite a few electronic ones. They have an internal clock and simply totalize the kWhr into two different 'registers' based on time-of-day. Both are measured by the 'meter-reader' and then billed accordingly.

Another technique for high-usage has been to record peak-power and total demand every 15 minute interval with a 'timestamp' supplied by an internal clock. Then the meter 'phones-home' every week or two, downloading all its recorded data directly to the utility's computer system. These require a dedicated phone line for the meter, typically not your residential service.

(these are US techniques, don't know in UK)

daestrom