How does my energy saving meter work?

[iloveroman]

Hello!

I've just brought an Energy Saving meter, to see how much electricity my household uses and I'm kinda curious as to how it actually works.

It's an efergy standard meter.
It has a clip that you place on the wire leaving your household meter, which seems to have a magnet in it.

I get that it will be using the magnetic field around the electrical wire but I don't really understand how.

Any help would be appreiciated, as it's been troublesome to find infomation and I'm determined now!
If this isn't the right spot, inapproprate etc, please let me know!

Cheers

Lot

 

[Bob S]

Is this a simple clamp-on-ammeter that clamps on to the hot wire only? If so, it cannot differentiate between real and reactive power. Even so, it could be useful in recording instantaneous amps. Does it integrate, meaning amp-hours? Even more useful. Most useful is a wall-plug device named "Kill-a-Watt" (TR) that differentiates between real and reactive power.
Bob S

 

[russ_watters]

Is this it? http://www.efergy.com/e2.html

It measures amperage via induction, then assumes a voltage and phase to calculate wattage.