How can I monitor electricity usage in my home?

July 11, 2006 4:31 AM

How can I monitor electricity usage in my home? More specifically, how would you go about making a home-brew version of the Wattson

This neat, but hugely expensive gadget shows your electricity usage in real time. Although the site lacks details, I presume it works using induction with some kind of sensor placed near where the electrical main enters your house.

Ignoring the wireless aspect, the funky flashing lights, and various display modes, would it be relatively easy to come up with a similar device myself with little electronics knowledge? Where would I start? Or are there more affordable alternatives available? (I know about the kill-a-watt, but am looking for a whole-house solution)

posted by blacksky to Technology (10 answers total)

I had my electrician install two extra meters near my main power box. I can patch any of the breaker circuits individually into one of these meters. (I use the water heater and air conditioner circuits.) He got the meters at a junk yard, they were both discarded after people had tried to tamper with them to cheat their electric bill.

It would be really cool if there was a cheap inline meter that could be plugged into a wall socket like a power strip.
posted by StickyCarpet at 4:40 AM on July 11, 2006

That looks like voodoo science to me.

The Kill-a-Watt is mentioned a lot on geek forums as being worth the money. Pretty cheap, under $30.
posted by Malor at 4:41 AM on July 11, 2006

It depends on what level you're looking to monitor - a single circuit? The main electrical feed coming in to your house? You'll need an appropriately rated device, depending on what level you want to measure.
posted by skwm at 5:19 AM on July 11, 2006

If you want to go crazy, do what this guy did, and build monitoring for every circuit in your house, sampling at 3 second intervals.
posted by tomierna at 5:27 AM on July 11, 2006

I'd love to buy one of those Kill-a-Watt devices, but they're only designed for 110V.. what about the rest of the world who uses 240V? Anyone know of an alternative?
posted by snarkle at 6:19 AM on July 11, 2006

snarkle: this article gives a couple of recommendations.
posted by biffa at 7:04 AM on July 11, 2006

If you just want to get the usage for the house to a spot near your desk, you can certainly get a metering device with some kind of data out - I used to work in the "remote telemetry" field and tehre were a few devices that used a protocol called LonTalk, but it would probably be expensive to get it all set up. Presumably you can find an X11 or even ethernet power meter nowadays.

Or you could set up a webcam pointing at your existing power meter. Maybe even be able to do OCR on the readings to track changes?
posted by mzurer at 7:26 AM on July 11, 2006

Best answer: Hack the meter. Here is one person who did just that. If you have automated meter reading you may be able to hack into the radio output.
posted by caddis at 7:28 AM on July 11, 2006 [1 favorite]

Learn to read your meter (if you are looking for a whole-house solution). It ain't rocket science and you can google for instructions.
posted by i_am_a_Jedi at 7:28 PM on July 11, 2006

snarkle: Better answer: Maplin do a Plug-In Mains Power and Energy Monitor, yours for £12.49. Coincidentally enough, someone just walked into my office to show me the new one he'd just bought. We also did a little experiment to see whether plugged in mobile phone chargers really draw as much power when not charging as they do when charging. My Nokia one doesn't.
posted by biffa at 8:48 AM on July 12, 2006