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Old 29-07-2012, 14:05   #1
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Trying to piggyback 220vac US to 220vac UK...

I'm working on an older Oyster 55 with UK 220vac 50hz. The Genset onboard had 220 60hz on the spec plate. I accepted that and did not check. When I checked the circuits later, shonuff...they were 50hz.

I've already installed a 50amp 220vac 60hz shore connector.

Before I learned about the frequency difference I thought it a simple piggyback connection of the 220. They would NEVER be plugged in at the same time. I also ran my 220 through a 30 amp 2 pole breaker.

My attempt was to make the connection at the selector switch. Shore is shore...right?

Without any loads, closing the connection caused the breaker both onboard and the pole to trip.

The goal is to be able to run the inverter/ charger while in US waters. 110 vac outlets are already in place via transformers.

I know going from 60hz to 50hz will affect efficientcy. Not sure of the reverse.
Let the forum begin.

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Old 29-07-2012, 15:23   #2
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Re: Trying to piggyback 220vac US to 220vac UK...

Umm, US 220 volt power is 3-phase. Rest of the world 220-230 volt power is single-phase. They are totally different animals and entirely incompatible. Shore is definitely not shore.

If you're planning to leave the boat in the U.S. and want to be sure to be able to use US appliances, you would be better off converting it altogether. You might not need to change the genset -- just let it run a separate battery charger and then run your AC gear off an inverter.

Or just leave it like it is and use rest of the world appliances. You don't say what kind of inverter/charger is on board, but many of them will work on different voltages and frequencies. If not, you can change the inverter/charger, or add an isolation transformer (a good idea anyway) and use the voltage step-up feature to run your inverter/charger.

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Old 29-07-2012, 15:42   #3
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Re: Trying to piggyback 220vac US to 220vac UK...

The simplified answer.

European 220V 50 Hz you have one hot wire and one neutral wire and a safety ground wire.

US 240V 60 Hz power you have two hot wires one neutral and one ground safety. Each hot wire is 120 V if connected with the neutral or 240 V using the two hot wires.

So if you are trying to mix US 240 V and EU 220V you are probably mixing hot and neutral wires in your boat and that's why you are blowing circuit breakers.

Also VERY DANGEROUS. If you don't completely understand these differences I highly recommend getting a pro to set up your system.

The water is always bluer on the other side of the ocean.
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Old 29-07-2012, 15:50   #4
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Re: Trying to piggyback 220vac US to 220vac UK...

On US docks, you will find "220V" at a 50A 240/120V outlet. Key things to note are:

1) It's going to be between 230V to 240V, not 220V. You will need to be sure your appliances are OK with the greater voltage.

2) As you know, it will be 60Hz, not 50Hz. You will need to confirm that's OK with your appliances too.

3) Although Dockhead is correct that there is 3-phase power in the US, what comes out of a dock plug is single phase, either 30A@120V, or split-phase 50A@120V/240V.

4) 30A outlets are all single phase 120V, not 240V

5) To pick up 240V, you will need to attach to a 50A outlet. You will need a 50A cord up to your boat breaker which can be 30A to protect the boat wiring from overload.

6) The 50A outlets are split phase 120V/240V (L1, N, L2). 240V is available between L1 and L2, and you don't need N unless you need 120V.

7) Some docks have 100A service for mega yachts, but I'm not sure how it's set up. It might be 100A split phase, or it might be 3-phase. I don't know, but I doubt you would want to connect to that anyway.

Now you might now more, or you might be even more confused :-)
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