Power usage monitors like the Kill-A-Watt are pretty cool, but what if you want to monitor usage for your whole house? What if you want to track usage in real time throughout the day, without stepping outside to read the power meter? What if you could do all this without messing with mains voltage. Kevin tipped us off to this Instructable by jasonT which shows you how to do exactly this.

This Instructable details a real-time web based household power usage monitor. The end result is a live chart in a web page that updates every 10 seconds with the instantaneous power usage for my entire house. The electrical current is measured on the main lines entering my home with AC clamps. The signal is then conditioned with a simple circuit and monitored by an ioBridge module. The ioBridge module takes care of feeding the data to the internet without the need for me to host a power hungry home web server. By using ioBridge widgets with a few JavaScript API calls on my web page, I am able to chart the data with Google Charts as it is measured and make kilowatt-hour calculations in real-time.

Instead of doing anything with the mains power, the author uses an AC clamp to sense power usage. It’s basically a transformer coil that you can easily place around the incoming power line, no wiring needed. It outputs a low voltage AC signal, which can then be converted to DC with a simple circuit so that it can be used as a measurement device for embedded systems like the ioBridge or an Arduino.

We’re all trying to cut our energy usage, but without decent measurement tools it’s hard to really tell when or where your major expenditures are originating. Hopefully, this sort of device will be a standard feature in most homes in the next 10 years, but until then you can make your own.

What tools are you using to measure your home power usage?

Real-time Web Based Household Power Usage Monitor