Well, this morning I was leveling my bed.
The Brass Nozzle touched the Raw Aluminum Build Plate on the Hot Bed, and ZAP!
A wild Bright Orange Arc Strike appeared! It was REALLY orange too.
I think it was the PLA burning like a flame. It was at 200C.
Now I know I hooked everything up right, I'm not stupid with wiring. I've welded things at 12v / 200a before.
So I am sure I don't have a grounding fault.
Using a multi meter I confirmed that the Raw Alu build Plate is electrically isolated from the Hot Bed Circuit.
If I don't have a grounding fault, how did this happen?
How did touching the nozzle short out the thermistor???
I've done a google search and got nowhere promptly.
EDIT: Hmm https://softsolder.com/2011/01/09/thing-o-matic-mk5-extruder-static-control/
Could printing (I have about 10hrs on it now) have made a charge separation from the frame / print head?
Edit2: I don't think it's static discharge. My printer was off for a few days and I was touching the build plate taking pictures of models....but not the print head. hmm...It has been very very humid this weekend.
Double black spot is where the wire melted like a fuse. Melted out a whole mm.
Graph shows the arc out event. Wire melted about 30s later and dropped to -14C (Open Circuit).