comments:
I have confirmed it is inductive coupling from the furnace. I can measure AC signals on the line which disappear when the furnace is off. I was taking measurements just fine and was able to turn off the power supply without issue after a reading, but after stopping data on excel's data streamer, it surged and fried the arduino, the desktop's motherboard, and the sensor. By the looks of it I will have to take measurements very quickly while the furnace is briefly off, then turn it back on to maintain temperature. Do you think this module is sufficient to isolate the connection to the arduino from the computer to prevent this from happening again in case I forget to turn off the furnace? https://www.amazon.com/Jhoinrch-Isolator-Supports-5000Vrms-Isolation/dp/B0FR4SW7ML/ref=sr_1_19?dib=eyJ2IjoiMSJ9.k-ULwk0kf1AQK8JGLOvrzOXkw-j2N3-_VgUI6kOvies.ZLNacvfwCImiJgwb7Z8ZeSCrUyttDGtyAoQscMLeji4&dib_tag=se&keywords=usb+optocoupler&qid=1781363114&xpid=PIRv2vwnzZaZV#averageCustomerReviewsAnchor