Hello,
I hope to be in the right section, I refer to this article of the old forum: firmware for SCT-013-030 | Archived Forum
I have a SCT-013-030 and I created a small circuit (as you described here: https://openenergymonitor.org/emon/buildingblocks/how-to-build-an-arduino-energy-monitor-measuring-current-only) with two 10K resistors and a 10µF capacitor.
Always following your instructions I have not mounted any bourden resistor and I modified the ct1.currentTX (1, 111.1); line in ct1.currentTX (1, 30);
when I run the test, without any electrical source in the sensor, I get a reading of about 80W.
How is it possible? Where did I go wrong?
Sorry for my English 
Thank you.
What you are seeing is most likely electrical noise. If you search the old forums for “noise”, you will find very many results, most of which say much the same thing.