[kevin.li.rit]

You have to refer to r44

Application Minimum wire size
40A circuit 12 AWG (2.052mm)
30A circuit 14 AWG (1.628mm)
20A circuit 18 AWG (1.024mm)

With that said, I would recommend soldering wires to the terminals of the fisher price motor. I find it difficult to put 12 gauge wire on the terminal and I usually use 14AG and 30 amps for the FP.