Lots of folks have (rightly) warned against up-sizing breakers. True for both AC and DC circuits. Wire size is certainly the determinant for ampacity. However, you may very well luck out and find that the wire size is already good enough because the builder was simply using the wire from the spool in his hand rather than switching from spool to spool. Most of the circuits in our FuHwa are run with the same wire, unhelpful when tracing circuits(!). (As an example, I wired all the typical branch circuits in the house with #12 AWG even though the breaker suitable for a particular circuit was 15 amp.)