Site meter not updating
The CTs are available from ITead Studio and usually have about a two week lead time.Besides the 200 Amp version I used, there are other styles and ratings available.These things are a coil of wire that wraps around the wire and inductively measures the power flowing through a wire.There are a ton of web descriptions of these devices so learning about them was relatively easy; finding one at a reasonable price was a different matter.Finally, I found a nice device that would work at my house.I have a 400 Amp service that splits into two 200 Amp distributions.Yes, I know that the transformer could be used to power the Arduino, that will come in time, but for now…it works, don’t fix it.
The voltage output has to be compared against some standard before you actually know how much power you're using, but you can certainly tell they are working.
Originally I had a Wishield for wifi since there is no network connection near the power panel, but Wifi proved to unreliable over time.
I changed my link to an XBee and eventually installed them all over the house.
I took his Arduino code for power monitoring, modified it to work with two current transformers, and added network code to serve data based on a simple html request.
Trystan has single phase 240 power and didn’t need to consider using double CTs, but don’t worry, you simply tie the two of them in series if you have split phase 220. The transformer on the left is a 10V center taped step down to provide a reference for the AC mains.