Parts list: (via amazon)
* Makerfocus ESP8266 Module ESP-12E NodeMcu
* TMP36
* Wall Charger, 4.2A 21W Dual USB Universal Portable Charger
What I found out: A) you can not tap one side of a 220v-gnd to the wall charger because the GndFault breaker trips B) the wall charger says: 110-220v, so I just connected it up across the 2 main lines and had 5v usb. [ yes I turned the power off - I understand the Darwin effect]
The C code is standard wait for a http hit, read the tmp36, report as a webpage. My desktop, crontab */10 runs curl http://hottub, results to mysql.db. I'll be adding low temp alarm text message and including Phplot - because I can
But the main reason for this post is: the tub runs on 220v which 110v phA, 110vphB, gnd. No neutral. But the wall charger (overkill on amps but it was in my parts box) works and that's all I care about.