240v Shore Power Connection

[rwidman]

Originally Posted by sailinglegend

............ have an isolation transformer fitted by a qualified Marine Electrical engineer who really knows his stuff to step the voltage up from 120 to 240v, ............

This is the correct answer and the simplest and most correct way to do this. No modifications to the dock and minimal modifications the boat. It could be set up as a plug in so you can use it where needed and revert back to the original when needed.

[jmschmidt]

Sorry, this conversation kind of got away from your original question. Which I think was: What to do with a 3-wire, 240vac, 50hz boat so as to connect to either a 120vac, 60hz, 30 amp or 240vac 60hz 50amp standard US marina shore power installations. Right? There is not much you can do about the frequency (hz) but check with Charles Marine, they make an extensive line of marine transformers which will convert electricity in every which way you can imagine. They are big, heavy, expensive units that run hot (and need ventilation) but Charles may be able to help you.
Capt. Jack

[goboatingnow]

God I answered this before

US 240 Vac is called split phase, but this is a historical misnomer. all it is is 240VAC single phase with leg effectively floating. if you take a isolated oscilloscope, and connect it across the two hot wires you will see a standard single phase waveform.

in the EU, while increasingly uncommon, floating 230VAC is seen, hence reverse polarity lights on a EU boat sometime makes no sense and are not typically fitted. The boat if wired to code must be safe with the hot and neutral mixed.

Its entirely "possible" to connect a 240VAC split phase system directly to a EU 230 VAC 2 wire system. Note that US split phase is a "two wire" system , it is not 4-wire, thats just whats at the plug.

HOWEVER, the main safety issue is that while there should be no neutral to ground wire connections on a EU boat, they could have been added. SO the first thing to verify is that there is no connection on your boat between any of the AC wires and protective earth.

Secondly you really need a RCBO, a residual current circuit breaker, if this is a EU boat IT WILL BE PRESENT. This will at least go aways to protecting inadvertent shorts to ground.

There is no specific issue with such wiring, in Europe, one never ever assumes the neutral wire is " dead" and it is afforded exactly the same protection as the live.

without a RCBO , The other issue is that you do have an unprotected fault path from one side of the split phase to ground. this will not be run through your boards AC breakers. But your RCBO will catch it.


SO here my checklist

1. verify no inadvertent live or neutral connection to protective ground on the boat ( do this with a dead AC system !!!) , i.e. there should be no short. ( you have in effect already tested this by the fact that your boat powered up on split phase !!)

2. Ensure a suitable whole boat RCBO is fitted.

3. Preferably have double pole AC breakers in your panel, many boats now do , but not all.

4. If you don't understand this, DONT DO IT.

5. its not a great permanent system.


The reverse polarity light is itself is not an issue and is somewhat meaningless in europe. Your boat should be AND MUST BE under CE regs , still safe if the polarity is reversed.

dave

[goboatingnow]

Originally Posted by sailinglegend

You have also posted this question on two Cruising Association forums that I have responded too and yet you still say you don't have the answer?

One very clear message here has been not to play with and re-wire plugs yourself. Here is my response to your question on the CA Forum.

Whatever you do don't take advice to take the two hot wires and connect them to the live and neutral on your boat. This will cause reverse polarity lights to come on and means that the normally safe Neutral bus bars which would normally be at around zero volts are now at 120v. Yes this will give you 240v but if there are other faults on the boat then this could be a disaster. My neutral bus bars on an American built boat are exposed in a large area above the engine where tools and other AC and DC cables and bus bars are routed. Playing about with AC could kill you or someone swimming in the water around your boat. There are plenty of documented accidents about "messing about with AC". Water and AC don't mix well.

There are two answers, the first and simplest is to have an isolation transformer fitted by a qualified Marine Electrical engineer who really knows his stuff to step the voltage up from 120 to 240v, the second is to have a US shorepower socket fitted with the 120v split phase feeds wired to dedicated extra 240 sockets that just run from the new 4 pin shorepower fitting. Any permanently wired-in AC loads like an immersion heater would have to be re-cabled with a standard 13amp plug and plugged into the new US 240v sockets when in the US or into the UK 240 v sockets when in the UK.

The other important consideration is to make sure your shorepower charger will work on ANY input voltage and frequency, or buy a second maybe smaller charger that can be used to charge the batteries anywhere. This can supply power whilst your 50 Hz inverter is running to supply your 240 volts AC at the correct Hz for frequency dependent equipment like washing machines or Air-Con. It is better to have 240 volt 60 Hz kit that will work well in 50 Hz countries, it will also run slower in the UK but will work fine - just not as efficiently.

No European Boat built since CE regs, would be wired as you have stated with exposed neutral busbars, these could easily be live in any marina in Europe anyway, as reverse polarity checks are uncommon and often impossible as their is no neutral.

In europe the boat is wired with the assumption that either wire could be "hot" and the whole boat RCBO , and equally the mandatory one of the marina supply pillar is there to ensure protection

[sailinglegend]

Originally Posted by goboatingnow

No European Boat built since CE regs, would be wired as you have stated with exposed neutral busbars,....
In europe the boat is wired with the assumption that either wire could be "hot"

Just to let you know my boat is a Hunter - built in your wonderful US of A!!! As you say both wires are hot in your 240 volt system, so what were Hunter doing.

If they don't know what they are doing how is John Doe gonna know what to do, especially with all the conflicting, and very bad advice here.

If you have to ask cos you don't understand what you are doing - don't do it - you should have said that at the beginning of your post and not at the end, instead of giving the poor guy some hope!

[Sand crab]

Originally Posted by sailinglegend

Just to let you know my boat is a Hunter - built in your wonderful US of A!!! As you say both wires are hot in your 240 volt system, so what were Hunter doing.

But they are both hot at 120V.

Look at this.

Important conclusion
There is a 240 volt voltage difference between the neutral and the hot conductor in the 50 Hz system and only a 120 volt voltage difference between the neutral and each of the hot conductors in the 60 Hz system.

That is why an appliance designed to be connected onto the 50 Hz system cannot be used safely on the 60 Hz system without first having a proper technical inspection done, followed by any necessary modification work done to ensure that the appliance can be operated safely because, in the main breaker box, at the point where the 60 Hz "neutral" gets connected to the ground, this difference will cause serious problems!Can you plug a 230V 50Hz appliance into a 240V 60Hz outlet

[jmschmidt]

How do you account for Japan at 50hz and 100vac? I bought several small (and cheap) appliances there back in the old days and they worked fine in the US. 385 Yen to the Dollar.

[Sand crab]

The Japanese 100V system (50 and 60 hz) is close to the US system. The only difference might be in motors like refrigerators have. Both are way different the 240v 50hz system.
Electricity in Japan