Choosing power cord's line width depends on voltaic magnitude.The electricity is bigger power cord needs wider vice versa.It deals with PCB board as the same. Besides of electricity,you should thingk over minishing power supply coupling while you are choosing power cord.Therefore if condition permits ,choosing a wider one is better. Currently power cord's line width is 1mm at least,even though the electricity cross in it is no more than 1 mA.
