Burnt some Spaghetti!

Hi Folks,

I am venturing down the Rabbit hole of wiring at the moment and noticed two fried wires on my bulkhead connection. One is coupled with a black wire, I think it was originally white? The other one is green.

1. Just wondering what might have caused this so I can check and hopefully fix it from happening again.
2. What are the name of those connectors in the bulkhead? Something 56?

Cheers,