Hi premkumar,
you didn't specify with which kind of board you had that "burning sensation"
.
Using AC instead of DC won't make a difference calculating for the power dissipation in a certain PCB-trace.
Of course going from low voltage (5-12V) to 230V (or 400V) the power dissipation is about 20 times as much as using 12V at any current. It is 33.3 times higher at 400V (using 12V for comparison).
Trace distance can be minimized (if space is an issue) by using a solder stop mask.
However trace width and length are decisive for burning traces under a certain load.
Relays are normally connected to some screw head terminal. Keep traces as wide as possible and as short as possible (ideally not longer than 10mm).
Also consider to use PCB material with 2oz of copper instead of standard material using 1oz.
Boncuk