Ballast Wireing Question

I'm putting new DPDT switches in my buddies boat. The switches that are in there now require relays and we have been having electrical issues with them the last year or so and now this year they arn't working. I'm just wondering what size wire I would need if I ran one wire from the battery to the dash and then split it into three 12 gauge or three 10 gauge wires to go to each switch. We are running two ballast puppies and one johnson pump (not sure on the numbers because they are all worn off). Looking through past threads on ballast switches it seems the Carling 20 amp 12 VDC switches should work. Looking for some advice on what size wire to run. The ballast puppy tech sheet say that 12 gauge for 10-25' and 10 gauge for 25-40' so I'm thinking the 10 gauge.