PCB trace clearance for AS3100

If anyone can help me understand this I would be greatly be appreciated…
On AS3100 they state that on PCB board traces can be 150v per mm of clearance of peak voltages
so at 23o V rms (320 Vp) I would need 2.2 mm clearance?
So theoretically I could not use a 1.6mm thick board and have traces along the bottom and top cross each other - I this a correct assumption or am I missing something

thanks in advance