Although products are becoming more and more available for monitoring your home power usage, I'm one of those idiots who can't leave well enough alone and who would rather shell out $100 and hours of my time in order to save $20 and learn something in the process. Building on the fine work of Trystan Lea and others at OpenEnergyMonitor.org
as well as various and sundry web sources and acquaintances the result is a self-contained Arduino shield for monitoring the energy usage of your home using clamp on current transformers, an ethernet shield, and an Arduino. The resulting Energy Monitoring Shield has a built in switching power supply and with mains voltage (120VAC in the US) to the board can do power factor correction as well. With mains voltage to the board it is also more dangerous than your typical home electronics project and as such has been rejected for distribution by commercial maker outlets like adafruit and sparkfun. So take that as a warning, and if in doubt, keep one hand in your pocket and out of puddles when handling the board.
In simple terms, the power monitor shield provides an AC to DC power source for the Arduino and Ethernet Shield, samples the AC voltage waveform for power factor correction, and uses the current transformers to measure current draw of branch circuits in your home breaker box.
* Connectors for easy integration with clamp on current transformers
* Built in 120VAC to 5VDC switching power supply for powering Arduino and Ethernet Shields
* Monitor up to 5 branch circuits at once, of which up to 3 can be two wire single phase 240VAC
* Power factor correction for power measurements
* Code interfaces with Pachube
) internet of things for data presentation
* Makes your breaker box a mess
DISCLAIMER: This project requires working with 120 and/or 240VAC, which can kill or seriously injure you if you are not careful. Please be aware of and follow all applicable safety practice, electrical code, and Geneva Convention guidelines.