Bad connection on the neutral buss....that simple. Those connections will work loose & the resulting bad connection gets hot!
The first response to the OP,"Wouldn't it better to replace what caused the wires to burn?" was somewhat odd. Must not have understood what was going on.
I would suggest you tighten up ALL connections on that neutral buss bar, strip back the burnt wires & reconnect. "if" the buss bar gets hot again you will see the discoloration.
It's a good idea, like the previous poster suggested to inspect entire 110VAC wires. Also pop the covers on the 120VAC fuse panel & Xfer switch & look for loose connections. Pull att the lower drawers and inspect/clean.
On my prior 93 PaceI found a loose common wire in the 50Amp Xfer switch. Cleaned up connection & tightened & all was back to normal.
During another inspection just last week I found a 12VDC 4 lug grounding bar. ALL THREE ground lugs where finger tight! The Furnace, Pump switch & Vanity lights where connected to that buss bar! Just last year the OEM ignitor board in that furnace failed, might have been a result of a loose ground wire!
