Jim What you were told is correct. Well, largely correct, but specifically targeted to a RESIDENTIAL APPLICATION... First, I forgot yesterday to point out that if you change the breaker at the house that feeds the pedestal, you will protect all of the outlets at the pedestal. So, in your case, your pedestal has one 50A outlet, one 30A outlet, and a pair of 15A/20A outlets. One 50A, double pole EPD at the dock service origin will protect all of those outlets. Yes, one 50A double pole GFCI will almost certainly be OK in a residential situation. Here's the way this works. ALL ELECTRICAL DEVICES leak some tiny amount of power, and a boat is a collection of many electrical devices. Water heaters, transformers and motors/compressors leak the most. Lightbulbs and toasters, not as much. Electrical device manufacturers deal with codified standards for max electrical leakage, and all devices that are certified by UL or eTL Testing Labs have been tested to comply with those standards and many others. Your boat leaks. ALL BOATS LEAK. The real issue is to keep that cumulative total leakage to a very small amount, safe for human (and pets and wildlife) lives. I have a handheld meter that tests for leakage at the microamp level. So I can say with confidence that my boat leaks ~3.4mA when EVERYTHING on the boat is running at the same time. That leakage is measured on the Green AC Safety Ground conductor. No one ever does this, but if you measure your home's green safety ground at the main service panel, you'll find much larger leakage than that. That's why in most of the rest of the developed world, 30mA RCDs (Residual Current Devices) are required as residential dwelling unit main disconnect breakers. So, if I were plugged into a pedestal fit with an EPD, with my 3.4mA leakage, I would be well within the 30mA setpoint of the EPD. Ergo, Sir Knight, no problema. The issue for marinas is, they often have docks with 30, 40, 50 boats or more. Now multiply my 3.4mA by 10, 20, 30 boats, and you can see the problem for marinas. But in your residential situation, you won't have the multiplication factor, so a GFCI will be OK for that application. UNDERSTAND though, GFCIs are rated for a range of 4mA - 6mA, so the low end of the range could create nuisance trips, and you may need to swap out a breaker to solve nuisance trips if you have that. Home Despot has a box that's made for outdoor Spas. It is comprised of a metallic housing containing a 50A, double pole, GFCI. I like it for a net new residential solution for a boat dock. For you, a 50A, double pole GFCI breaker suitable for your dock drop would be fine. Since you have a 100A breaker today, downsizing to 50A will save you one-and-done expense. A 100A, double pole, GFCI breaker will be a special order for a big box store, and more expensive. It's unlikely you really need more than 50A. Even with a 50A boat, when the batteries are charged and all is nominal aboard, even with heat pumps running for heat/cooling, you won't be drawing 50A. But if you want to go same-for-same, then get a 100A, double pole, GFCI breaker. They'd be available on the Internet. Yes, your breaker has a single operator arm. But the breaker itself is double wide, and if one legs trips, the breaker will trip the other internally. Both poles operate together as a single unit, regardless of where the cause is. Hope this helps. Jim Peg and Jim Healy, living aboard Sanctuary http://gilwellbear.wordpress.com Monk 36 Hull #132 MMSI #367042570 AGLCA #3767 MTOA #3436