240 VAc Boat

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Vanclisg

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Jun 24, 2020
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First time question, looking online at a Californian sundeck, the listing says boat is 240 Vac. I was told it combines 2 120 Vac to get 240. How does that work? Do I need to connect 2 dock power cords? Two 30 amp cords or a single 50 amp to a splitter to the two 30 amp inputs. On my previous boat I had two 30 amp inputs, one for house and one for the air conditioners.
 
Typically that will be one 50 amp 240v cord. Pics of the electrical inlet of particular boat you are speaking of would be helpful. Here in the US on land and at sea 240 is comprised of two 120v legs.
You will find Calder's "Boat Owner's Mechanical and Electrical Manual" quite helpful and make you a pretty educated buyer on these matters.
 
That type of power is very common on larger boats. The shore power is 50A, 240/110V where two legs of 120V combine to provide 240 as you describe. Most boats do not use the 240 unless they have a really big A/C, but divide the 240 into two separate 120V circuits that each power a panel of 120V breakers, some of which feed the A/Cs.

This type of power supply works with a dock with the required 50A power outlet, but can also work with an older dock with just 30A single phase power. You use two separate 30A outlets that are combined in a Y adapter to feed the boat. If the 30A outlets are on separate phases they can also be used to produce 240V but like I said, most boats don't use it.

If you only have one 30A shore power outlet then with a proper adapter you can hook up to the boat's power inlet, but usually you can only power one of the two legs of power. I haven't seen it done, but theoretically you could power both legs (as long as there isn't a 240 circuit on board) but be limited to 30A total.

Wow, I am tired of writing. Like I said that power arrangement is very common and more marinas are offering 50A/240/120V outlets.

David
 
Thanks for your replies. I didn’t realize that the 50 Amp dockside outlet was 120/240 Volts.
 
Thanks for your replies. I didn’t realize that the 50 Amp dockside outlet was 120/240 Volts.

Some 50 amp outlets are not 120/240. Check pedastel carefully in a new marina.
 
This is a confusing subject. First off the US standard is is 110 and 220 while much of the world is 220. To make it more confusing marine power cords are marked 30a 125v, 50a 125v, 50a 125/250v. The last being made up of 2 110v legs. Now those two legs could be a single 50a 125/250v cord or it could be two 30a 125v cords or a splitter could be added to either end of a 50a 125/250v cord.

Now the boat itself could be all 110 or it could be a mix of 110 and 220. It is not uncommon to put basic house items on one leg and heat or AC on the other leg all being 110 applications. It’s also possible to actually have 220 applications that pull a 110 from each leg to make 220. It’s also possible to turn one 110 leg into a 220 leg. Finally, it’s possible the boat is euro specification and everything is 220 on the boat. Make sure this is not the case. If it is, move on, it’s not worth the head ache.
 
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