Melting plastic from wiring at terminal block

[Ed]

Hi everyone,

I purchased a used S1 Dream about 18 months ago (manufactured 2012) and it's been a wonderful machine. There have been a couple maintenance issues but nothing unusual for this age of machine and to me it's well worth keeping the machine going. Last year I replace a couple leaking elbows and tubing, and now I have my first electrical issue.

In brief, the last two days there has been a bit of an electrical burning smell. Took the covers off today to investigate properly. At the rear left side (when viewed from the back), I narrowed it down to the wiring terminal block area that is held to the side of the machine with two small bolts. I undid them to get a better look and pulled the block out a bit. On the back side of the block, the white neutral braided wire that runs directly from the power cable to the terminal block appears to have been getting hot and had melted most of the heat shrink around it. Unlike the other wires running into the terminal block, there was no rectangular-shaped plastic protector/insulator around this spade connector. The plastic protector around the spade connector on the adjacent white wire was partially melted and I think this was what caused the burning smell. The terminal block around these wires is discolored a bit but looks intact. The machine was otherwise working fine before this issue. I run it in econ/15A mode.

So far it looks to me like I need to replace the two spade connectors with new ones with insulated covers. Does anyone have recommendations on a product for this particular spot on the machine? I've read the past threads about melting plastic at the boiler terminals etc, but not this particular spot at the terminal block. Also should I be worried about any other possible root cause of this particular issue?

Any help is greatly appreciated! Hoping to get the machine back up and running soon.

[Ed]

Here are a couple photos:

[chas]

Yes, I've had this happen to the element connectors on top of the steam boiler multiple times but never in this location. Usually the cause is moisture getting into the copper strands between the crimp connector and where the insulation starts. This causes the wire resistance to increase which makes the connector get hotter and hotter until it melts.

The best crimp connectors have shrink tubing over the terminal which extends an inch or so back. When it is crimped into place you heat the shrink tubing and it shrinks up to the wire preventing moisture from getting into the strands.

Check out this page for one possible source:
https://www.amazon.com/s/?ie=UTF8&keywo ... c699aqsa_b

[Ed]

Thanks Chas for the quick reply! I'll be ordering some connectors soon and giving it a shot.