This non-invasive current sensor clamped around the supply line can measure a load up to 30 Amps, and allow you to calculate how much current pass through it. It can be useful for building your own energy monitor or for building an over-current protection device for an AC load. This current clamp can be used to detect a current of up to 30A. Simply clip it around the current source that you wish to measure and it will produce a (very) small AC voltage proportional to the current. The cable is terminated on one end with a standard 3.5mm jack (like a headphone jack).Use this to build your own energy monitor and keep your power usage down, or use it to to build an over-current protection device for an AC load.

Specifications

• Product Name: Non-invasive AC Current Sensor
  
• Model: SCT-013-030
  
• Core Material: Ferrite
  
• External Material: Plastic
  
• Input Current: 0-30A
  
• Output Mode: 0-1V
  
• Opening Size: 13 x 13mm / 0.5" x 0.5" (L*W)
  
• Output Plug: 3.5mm
  
• Dielectric Strength: 6000V AC/1min
  
• Working Temperature: -25 to 70°C
  
• Cable Length: 1.18m / 45.4"
  
• Total Size: 5.7 x 3.2 x 2.1cm / 2.2" x 1.3" x 0.8" (L*W*T)
  
• Weight: 63g
  
• Package Content: 1 x Non-invasive AC Current Sensor
  

 Datasheet

        http://garden.seeedstudio.com/images/b/bc/SCT013-030V.pdf