The ignition/light/gauges wire is getting so hot it's melting the ignition switch on my 2000 Harley heritage. I've replaced the ignition switch once already and the starter relay switch also. The longer the bike runs the hotter the wire gets. I by passed the ignition switch by hot wiring it directly and I can phsically see the wire heating up as the bike runs.

Have you added or have accessories been added?
Loose connections generate heat.
Is the corect fuse in place, or increased because of blowing.
I would use a DC amprobe and see what is drawing what.
When you say you "See the wire heating up", is it changing color? melting? smoking? glowing?
Do you see it just heat up at the switch? If so, loose connections generate heat.
Good Luck.