http://www.theenergydetective.com/index.htmlCheck out this company's products. I have used one of their earlier ones for years (240 volt single phase) to monitor instantaneous demand, daily kwh, max kw anytime during day. The current donuts are split type so easy to install. It uses power line carrier to get signal from panel to remote monitor. The two current donuts feed a transmitter which is connected to a breaker. You need to get on the same phase leg as the transmitter for the remote monitor to work. I think their latest products will deal with 3 phase and also provide a data feed to a PC for your own software or spreadsheet to massage. The cost and ease of use dwarfs most commercial metering arrangements.
Dave
