Here are some creative uses of current sensors:
Real-time Web Based Household Power Usage Monitor
What you need:
-cheap carabiner (what other use for those fake caribiners!)
-or use a $1 c-clamp for better results
-3' of small gauge wire
-a store bought clamp-on current sensor
Once complete, read your sensor with a millivolt meter ; such as, a multi meter, micro controller, arduino, etc
Step 1: Wrap the carabiner and calibrate
Next, slice/separate the wires of an extension cord in order to test/calibrate your CT sensor. If you try to sense both the load line and neutral line, the magnetic fields cancel and no current is induced.
Next, plug something into the extension cord. I used a space heater. Measure the amperage with a store bought clamp-on meter.
I measured 11.8 amps with my Field Piece meter.
The field piece has been calibrated so that 1amp AC is equal to 1milivolt AC (1AAC/1mVAC). My Caribiner sensor measured 0.3 milivolt.
11.8 amps / 0.3 millivolts = 39 AAC/mVAC
If you are considering putting this around any high voltage wiring, consider wrapping all exposed metal parts in electrical tape.