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Topic: Detecting Electricity Useage (Read 1 time) previous topic - next topic


Is there some sort sensor/circuit that could be used to detect when power is being used.

I would like to make a timer device that would be triggered and could track when and how long an electrical appliance is being used.

Example, sense what a computer of refrigerator is actually drawing power.  It does not have to know how much electricity is being used, but maybe send a rough value that could determine a trigger point when something is running.

Is there some sort of sensor or can an arduino circuit be built for this purpose?

Thank you in advance,


You can use a current transformer to sense how much current an AC appliance is drawing.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.


for reference, check out



Thank you.  For some reason I did not consider looking for "Current Sensor" on eBay.  I think I found what I am looking for.

In two weeks (from China) I'll find out!



you could google "kill a watt" if you do not want to build it your self.


If someone is consuming electricity, there must be current.


Make sure you fully understand what you are doing before using CT's. Open Circuit CT's, under Primary load, can be extremely dangerous and generate several thousand volts and extensive arcing. CT's should NEVER be open circuit under load. Worrying about how to connect to, and possibly killing, your Arduino would be the least of your concerns.

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