I hope you experts don't mind me asking this question but I have read about
this several times on the list and would like to understand the idea.

I have read 2 relay situations:

1. Installing headlights with greater intensity. Use a relay...

2. Install a relay in the fan switch to prevent the switch from burning
out...

So my understanding is that the addition of lights with a greater energy
demand draws more power than the wires can handle... so what does the relay
do?

thanks

peter