I think you'll find the core of the GFCI differential sense transformer saturates at a very low current.
There are products such as these:
Best regards, Spehro Pefhany
Thanks! My post as originally stated is wrong - the word "measure" has to be changed to detect if the GFCI CT saturates.
I'm glad you posted that - I had not even considered saturation, because all he wants to do is detect if there is any current. If gets any measurement at all, he knows the device is drawing current. I suppose I confused things by saying "measure" rather than detect.
Nice links, too. Here's another I like:
(Watch the line wrap)
Ed
I am detecting the current to my outside motion lights with a little current transformer (all electronics or Hosfelt a buck or so) across a
100k resistor and the input legs of a 324 op amp. (4 in a DIP) The CTs I am using will fit through a 1/2" KO in the box with the sense leads on the outside. I just looped the red wire through the CT. I am not sure what voltage is developed on the 324 but it dies work.
The chinese have perfected it, buy a cheap clamp meter, I saw one for about $20 bucks at a discounter.
you need to clamp round only one of the power carying conductors. you need a magnetic path around the cunductor and the pickup wire wound around that path.
Bye. Jasen
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