What would cause one of my wires on my Electric Water heater Reliance 606 to burn and almost catch fire in the top panel and how to repair?

Question

I had to change some piping on my Electric water heater that is a 40 Gallon Reliance 606 and after I replaced the pipe I started to notice a burning smell and noticed that one of the wires in the top panel which is yellow is actually starting to try and burn for some reason and it Melted the plastic around the wire as well but that was the only wire that burnt So can somebody please help me by letting me know what could cause this? and how can I repair it?

Answer 1

A loose connection on a high draw device (a water heater) will cause a point of high resistance and create heat. Enough heat that can cause the plastic to melt.

To repair it you'll need to replace the terminal block. cut back the wire with the molten insulation to a "clean" part. Or replace the wire with one of equal size. Check the torque spec on the terminals and follow them.

Answer 2

What causes that is NEC 110.14(D) Use a Torque Screwdriver, or rather, failure to do so. Recent science shows torque matters even on the small stuff.

That entire black thing with 3 apparent sections is a thermostat assembly. They're cheap, swap the whole thing.

While you're buying water heater parts, think about the sacrificial anode. Like museum ships, they'll last well beyond their design life if you keep changing the anodes.