115 and 220 shore power breaker amperage

I have purchased a 2000W (2kVA ?) isolation transformer that can be jumpered for 220v or 115v input that I think will meet my needs for lighting, battery charging, etc.

I plan to put a 15A breaker and a GFCI on the output of the transformer but on the input side it would need either 15A (115v shore power) or 8A (220v shore power) breaker to avoid exceeding the transformer rating.

I can think of any number of ways to arrange for the input breaker amperage to differ depending on input voltage and methods to choose between them, but is there a prefered way to implement this ?

Maybe a 220v shore power cable adaptor pigtail with a breaker in it, or some switching arrangement. I'd prefer not to run more cables than necessary inside the boat (it's a longer way than I would like from the shore power inlet to the panel) or to swap out breakers but I suppose it's not a frequent task so that may work. I even considered putting two 8A breakers in parallel and just turning one off when on 220 but I read online this is frowned upon. Or putting an 8A and a 15A in parallel and just leaving one or the other turned off. I'd prefer something "forgetfulnessproof" though but the transformer needs to be re-jumpered anyway so I can't eliminate everything.

Also, I was unable to find a dual pole 8A circuit breaker, can I simply use two 8A single pole breakers and mechanically link the switch levers with a nylon screw and nuts to achieve the same effect or do the dual pole breakers differ internally from two separate single pole ?

 

Did you buy just a transformer? Electronic equipment usually have a fuse already installed. Otherwise, you can install a breaker on the inside of the boat. You can use two breakers in tandem with a bar or cap that joins them. They sell them at the same place they sell breakers. You can get GFCI/Arc fault combination breakers too. I am not sure how the isolation transformer has two different inputs. In general, if you double the voltage on the primary, it also double in the secondary.

 

The transformer has a single input that can be configured for 220V or 115vV input using jumpers inside the transformer box, if it is correctly configured the output should always be 120V.

I think I'm just going to leave the 15A breakers on the input hot and neutral in place all the time. My understanding is that the breakers are mainly there to protect the cables which are all fine to 15A. The output will always be 120V and there is a 15A breaker on the output hot that I think should limit the load on the transformer to 1800W, also the transformer has over-temperature protection that should cut off the current if it gets overloaded, and if all else fails at least it is in a metal box.

Thanks for the guidance on ganging the breakers.