European shore power cord for 16 Amp 230 VoltsThis article discusses the easiest way to convert a European 230 Volt boat with 16 Amp service to work in the US with 30 Amp 120 Volt dock power.  The plug in the picture to the left is a 230 volt 16 Amp shore power cord typically found on European boats with less extensive electrical systems.  Such boats might have some receptacles, a water heater and a battery charger but probably not air conditioning.

Its usually not practical or economical to rewire the entire boat, especially for older boats.  The wires used for 230 volt are going to be smaller than the wires needed for 120 volt and so to change the boat completely would mean changing everything including all the wires.  This is more work that it seems as even on simple electrical systems the wiring can be quite extensive and it was built in to the boat it may be hard to access or replace.

For boats like this the best option is usually to get a transformer.  A suitable transformer for 16 Amp service is relatively small and inexpensive.  Together with a new main breaker, a new shore power cord and main inlet, the whole project can be done for somewhere around $1350.  The parts list below shows what is required.

Starting at the dock end you will need a new shore power cord for 120 volt 30 amps and you will need a new Deck Inlet on board the boat to connect it to.  

Shore Power Cord                        Deck inlet

Blue Sea 3116 Surface Mount  ELCI Panel

Next you want to have a main breaker inside the boat.  To meet the ABYC standards this needs to be a 30 Amp ELCI breaker located within 10 feet of where the power comes on board.  The Blue Sea 3116 Surface Mount Breaker Panel shown here meets the standard.  The ELCI protection offered by this breaker gives you a 30 mA trip and is primarily to protect swimmers in the water from electrical leakage. You will probably find there is something similar as part of the original installation but as it will be a 16 Amp breaker you won't be able to use it.


Isolation transformer

The transformer shown above is what changes the voltage from 230 volts to 120.  It is rated for 32 Amps and so is appropriate for a US 30 Amp service.  As well as changing the voltage it also gives the boat electrical isolation from the shore which is useful for preventing galvanic corrosion.  This is a relatively compact device that needs to be mounted in a dry area.  Its approximate dimensions are 14.25" high x 10.15" wide x 8.5" deep and it weights 53 Lbs.

Triplex 10/3 sold by the foot
For 30 Amp service the wire before the transformer needs to be Triplex 10/3  awg, after the transformer you can use the original wire which will be less.  If a circuit breaker was located beside the deck inlet then you can take the output of the transformer right there, otherwise direct to the main breaker panel.
The transformer only changes the voltage in this project, it wont change the frequency. If you have pieces of equipment on the boat specifically designed for 50 Hz they may not work exactly the same, for example the clock in your microwave may run faster on 60 Hz than on 50 Hz. Normally this isnt more than a minor nuisance but occasionally you may have trouble with electric motors overheating. This whole project is for European 16 Amp service only. If your boat has 32 amp service then this project gets exponentially more expensive, the transformers get heavier and bulkier and of course the costs go up.

If you are taking your US built boat the Europe you can do this project in reverse.  The concept is the same and the transformer works both ways.  



Date 8/10/2019

I am looking at importing a Sealine C330 boat from Europe to Canada - Its a slick model that just cannot be purchased here, lightly used, at a reasonable price. Its only 35 feet long so shipping is affordable. I have read many articles about how much grief it is to try and convert the electrical systems, replacing wires and appliances, but I don't see why it just cant be run as Euro boat inside after installing a transformer as you mention. If i ever needed a part I just order it online and it arrives from the UK within 2 days instead of maybe overnight - just like I would have to do here for any North American parts - Yes a few convenience receptacles for 120 power to run a laptop or shaver would be nice but that's about it. the cost saving is about 100K after shipping and duty - and these models are very rare here - certainly none used. Is the setup you mention above genuinely viable for this boat? many thanks

Shore confused

Date 4/24/2020

I find this to be a simple, elegant solution to what can be a complicated, expensive solution. The one addition, I would suggest is to use the output from the isolation transformer, and use it as the input for a DC battery charger. Make sure the DC charger matches your onboard battery DC voltage. In this way, shore power is stored in batteries, and this cancels the issue of frequency differences. Moreover, if someone needs AC power, then you use an inverter which converts DC power to AC power, and all the appliances onboard will work at the correct AC voltage and frequency since the inverter output will match the house AC appliances. If someone requires

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