Sizing of bonding conductors for Service is covered in 250.102. (C) covers Supply side of Service and (D) covers Load side of Service. I don't know that this is the proper place to look because a generator is not Service. But it appears that in some cases even for Service Load size the bond can be as small as #14 AWG. The Bond that you mentioned that was on the generator is probably sized per manufacturer's specs. If there is any labeling, UL, CSA, etc I'm sure you don't have to worry about the bond being sized properly. Now you had indicated that it was a 120/240v. 5500 va generator so the capacity of the generator is 23a. on 240v. or if your are running it straight 120v. you might, I stress might, get 43a, I question if you could even do that at all. So 60a. is not what you can expect from this unit.
