Ready, I installed a macerator pump on my coach. In my case, I ran 10 ga. wire from the coach batteries under the entry step back to the sewer compartment. I did not use a circuit breaker per se, but rather an in-line 15A fuse located at the battery where the wire was attached to the + terminal.
Other people have just tapped into the big hot cable going to the generator, not far from the sewer compartment (Darn! Why didn't I think of that?!!!)
I would keep my macerator on a different circuit than my water pump. JMHO.