2007 48 Sundancer ISO transformer

[Ray K]

As far as I know all of these models have either a 50A/240VAC ISO Transformer or ISO Boost Transformer that is between the 50A/240VAC shorepower inlet and the main panel. From the wiring diagram I just reviewed that would make it impossible to operate any of the 120VAC devices on the boat by using an adapter (single 30A/120VAC to 50A/120/240VAC) like you can on other boats without the ISO Transformer. Maybe someone can confirm this as we encounter some docks that only have 30A/120V power available when we travel.

 

[Joel_MD]

My 2005 390 Motor Yacht has the ISO Transformer. The seller included one of those $400 reverse "Y" adapters (link) that allows me to plug into two 30 amp outlets, but I haven't tried using it yet. I don't see how you could adapt a 50A 240 by plugging into a single 30A 120 outlet. The 240 volt outlets has two hot (120 volt) wires, whereas the 30A 120 has only one.

 

[CAMELLA]

I use a Smart "Y" adapter at my dock, current set up is two 30 Amp 120 volt outlets at the dock and the "Y" converts it to 50 Amp 240 volts. Works great. The adapter also comes in handy when travel to other marinas, gives you more flexibility.

 

[HUMPH]

You do need to ensure the (2) 30amp outlets are out of phase. The smart eye will not light up if the outlets are on the same phase. We usually test before connecting.

 

[Ray K]

Joel MD, The reverse Y will work as long as one 30A connection is on the opposite phase as the other. All your 120V and 240V devices will work. You will however be limited by the 30A breaker at the dock.
There is a Marinco adapter that goes from 30A/120VAC shorepower to a 50A/240/120VAC on the boat side. They just jumper L1 and L2 together. The neutral and ground pass through. This will allow the 120V devices to work. No 240V devices work. The problem I see with the 48 and perhaps many similar boats with an ISO isolation transformer only L1 and L2 hot go into the boat to the transformer. I don't think there is any way to power the transformer without 240V dockside power. The neutral does not pass through and therefore there is no return path either for the 120V devices. On boats without an ISO transformer the Neutral also goes through to the panel and therefore the 120V devices will work. In theory I think this is how this works and is a bit of a disappointment as we encounter the single 30A/120VAC situation in our travels. Looking for someone to confirm this for me.

 

[CAMELLA]

Here is the adapter you need.
https://www.amazon.com/dp/B0064N07EQ/ref=pe_385040_30332200_TE_item_image

 

[Ray K]

Let me restate the issue. I think it's been misunderstood. My issue is not using a smart Y when 2 30A connections are available. I'm already aware of this and have these adapters. The problem is that in some cases only 1 30A/120VAC connection is available. There is an adapter for this to get the 120VAC part of the panel to work. It works on Cruisers Yachts and others that don't have the ISO transformer. I am trying to find out if anyone with a Sea Ray 48DA or similar boat with the ISO transformer has ever found a way to at least get the 120VAC devices to work. I don't think it's possible but some people are creative so you never know.

 

[Steve36]

I know on my boat i have a connection that will take 1 - 30amp shore power cord. I believe that if you use this then only your 120V systems will run (which is on a separate electrical system).
I have not tried it yet but it would be logical for it to work in such a fashion.

 

[km1125]

Let me restate the issue. I think it's been misunderstood. My issue is not using a smart Y when 2 30A connections are available. I'm already aware of this and have these adapters. The problem is that in some cases only 1 30A/120VAC connection is available. There is an adapter for this to get the 120VAC part of the panel to work. It works on Cruisers Yachts and others that don't have the ISO transformer. I am trying to find out if anyone with a Sea Ray 48DA or similar boat with the ISO transformer has ever found a way to at least get the 120VAC devices to work. I don't think it's possible but some people are creative so you never know.

I realize this is a little older thread, but this is a common issue so I thought I'd update with an actual solution.

Just helped a friend out with this. He has a 470 that has 50A service and an isolation transformer. Even if you have two outlets available, those split cords will NOT work if they are GFCI protected.

The solution I used for him was getting a 120VAC to 240VAC converter off Amazon. The one I got was supposed to be 2000W, but it's really limited to about 10A on the 120VAC side due to an internal circuit breaker. However, that's PLENTY to run a battery charger and even a fridge (or other misc 120VAC stuff).

Here's some pics. Just had to make a custom cord that went from a 50A 240VAC connector to a 15A 240VAC connector (notice the prong are inline instead of parallel):

It worked great! His battery charger was charging at 35A because his batteries hadn't been charged since the beginning of Oct and he had used some 12V stuff since then. Nice to be able to top the batteries off in the winter!

 

[Morgan Jane]

I'm dealing with a problem with my ISO Boost. But if I take my ISO Boost off line, my 24v Batt charger doesn't work because it feeds off the 220V feed that runs thru the ISO Boost. Solution: I found a 110V - 24v volt charger. Nice little piece. I have the ISO Boost disconnected but I'm still charging my 24v batts. Pretty cool.

 

[ttmott]

I'm dealing with a problem with my ISO Boost. But if I take my ISO Boost off line, my 24v Batt charger doesn't work because it feeds off the 220V feed that runs thru the ISO Boost. Solution: I found a 110V - 24v volt charger. Nice little piece. I have the ISO Boost disconnected but I'm still charging my 24v batts. Pretty cool.

Be careful as if you bring that neutral and ground on the boat from the shore power, you have bypassed the galvanic corrosion protection that the Iso Xfmr provides. An electrical path has been created to corrode the boat.

 

[Morgan Jane]

Ah….great advice…..but in my situation it is quite contrare. My boat also has a second 50 amp 120v shore feed that also runs thru a ISO transformer. But you obviously know your stuff to pick up on that Nuance. Thank you for taking the time to help a fellow boater out. Love this site.