The eGauge is an energy monitor that uses power line communication to send data from your home's breaker panel over your home's electrical wiring to the HomePlug adapter, and then to your computer through a wireless modem.
From the eGauge overview page:
The Kill-A-Watt is an appliance energy monitor that can help you monitor your 120 V electricity users. You plug it into an outlet, and then plug an appliance into it to see how much energy it uses. Like most appliance energy monitors, the Kill-A-Watt only measures 120 V loads. Bigger electricity consumers like your AC units or your electric dryer are probably on 240 V breakers, so to monitor these you will need a whole home or whole home circuit level energy monitor.
Amazon Description:
The Belkin Conserve Insight Energy Cost Monitor is the main competitor to the Kill-A-Watt and Kill-A-Watt EZ. Both of these energy monitoring devices monitor single appliances on a 120 V outlet.
