I don't believe you have one on most Carvers. On a 50 amp service you'll often find one prong of the S.P. plug broken off (although some will leave the leg dead). Not sure how it's set up with twin 30 amp. Only boat I'd run with them was a Viking.
The owners manual shows one in the electrical diagrams... I'll have to go on a hunt. I'll look around the electrical panel and where the shore power enters the boat. I'm getting some pretty good electrolysis going on and am looking at this as one point to test and eliminate.
Thanks everyone, I did find this last weekend. Its immediately behind the AC breaker panel. First place I looked so I didn't have to do much hunting around.
Mine has 2 galvanic isolators from Charges (2006 466). They're located behind the closets in the aft cabin, which is really inside the swim platform.