Plugging a 120v boat into 240v

[Mr B]

This is a 36 foot Foretravel Grand Villa I imported from the USA,
It is 110 Volts, American,
To run the 110 Volt systems here in Australia, I have a 10 KVA Transformer in it to run it off my 240 Volts,
The transformer replaces the 6.5 KVA generator it came with, But I removed the generator out of it, and replaced it with Solar panels,
It runs both A/C units at the same time and all the other gear inside it by plugging it into my house with a 20 amp extension lead,

[Saltyhog]

Jammer has given good advice here. The OP would be wise to start here. I also agree with him that replying to this type of thread is frustrating.

[nebster]

If there is indeed an RCD at the shore pedestal, the possibilities in order of likelihood in my opinion are:

1. Downstream inadvertent neutral-ground bond. Follow jammer's instructions.

2. Defective RCD. Try another pedestal if possible.

3. Insulation breakdown. Follow ben's instructions.

If there is no RCD, or if none of 1-3 identify the culprit, then it is

4. Something more mysterious. Take lots of pictures of everything, draw a circuit that you think represents what you have, and post them here for us to look at.

All the other responses about 120V, split-phase, etc., are irrelevant for this (unusual) situation.

p.s. Another more expedient option might be just to run a cord straight to your charger and skip your distribution system. But you should fix (1) or (3) if you have them, anyway.

[CatNewBee]

Originally Posted by mikereed100

I am still confused as to why everything is OK at the panel until I try to send power to any of several unloaded circuits?

Its easy. Lets say you have an appliance 120V 2400W.
It will draw 2400W/120V = 20A and the resistance would be 120V / 20A = 6 Ohm

Applying 240V on a resistance of 6 Ohm would result in a current of 40A, that would trip the fuse, also the device would consume 240V * 40A = 9600W instead of the dessigned 2400W and would fry or start a fire. Good there are fuses to prevent this.

[nebster]

Originally Posted by CatNewBee

Its easy. Lets say you have an appliance 120V 2400W.
It will draw 2400W/120V = 20A and the resistance would be 120V / 20A = 6 Ohm

Applying 240V on a resistance of 6 Ohm would result in a current of 40A, that would trip the fuse, also the device would consume 240V * 40A = 9600W instead of the dessigned 2400W and would fry or start a fire. Good there are fuses to prevent this.

No, in this case the branch circuits are open. There are no loads present.

[CatNewBee]

And how do you actually know this? Do you have a complete diagram of the devices installed? It is dangerous to put 240V on outlets for 120V, you stick accidently something in and fry it. Take a 240V charger and plug it directly to the extension cord to shore, dont use the boat installation for this, it is unfit for 240V. In case you start a fire, there will be liability and no insurance will pay.

[nebster]

Originally Posted by CatNewBee

And how do you actually know this? Do you have a complete diagram of the devices installed?

Because I read the OP.

It is dangerous to put 240V on outlets for 120V, you stick accidently something in and fry it. Take a 240V charger and plug it directly to the extension cord to shore, dont use the boat installation for this, it is unfit for 240V. In case you start a fire, there will be liability and no insurance will pay.

Some things you write are true in this paragraph; some are not.

[CatNewBee]

Originally Posted by nebster

Because I read the OP.



Some things you write are true in this paragraph; some are not.

I read the OP too, and frown about the idea instantly.
On a boat installation can be hidden devices you not even know exist. Like 120V relay, that give shore power priority over inverter or generator, devices plugged in and in standby, A/C units, that are not on, but the electronic panels are connected to be ready to turn on... Any of this can get wrecked or cause the breaker to flip.

Even some chargers that are able to take different voltages have switches or bridges to configure the input voltage range. Not all are automatic like cellphone chargers.

It may be feasible to connect a 240V EU yacht to 240V dual phase US omitting the neutral, but it does not work vice-versa with 120V. In the EU there are 5 pin 3 phase outlets with neutral and shield allowing either 3 x 220V to neutral or 3 x 380V between the phases for power applications. I would never try to connect 220V between two phases on those.

And there are the 3 pin 220V in various different plugs (16A, 25A...) with phase, earth and neutral, usually protected by stray current protection and a double breaker fuse.

[sdowney717]

Originally Posted by Jammer

Because the neutrals are still all connected together and are a potential source of leakage.

Maybe so, but his system is not tripping power off until he turns on the various panel breakers. With just the main breaker on, does not trip off power.

He can rewire temporarily just to the main breaker output to get the charger going. And figure out the other problems, which he must do.

I have rewired many houses with new services and my own boat, so I know what I am doing.

Stuff like this is a pain for sure to find the problems, which seems to be all the distribution circuits as all of them trip off the breaker. But what is really confusing is why it does not trip on 120vac but only on 220 vac, which makes no sense if it is grounded neutrals, unless the power pedestal is doing some circuit checking.

An AFCI breaker WILL trip off if it detects a shared neutral, (I am not talking of a grounded neutral). Maybe a new GFCI breaker now also detects that, but they did not before.

My own boat has a Square-D panel, which I upgraded to AFCI - GFCI combo breakers. So most of my AC circuits are both AFCI and GFCI protected.

[CatNewBee]

Originally Posted by sdowney717

Maybe so, but his system is not tripping power off until he turns on the various panel breakers. With just the main breaker on, does not trip off power.

He can rewire temporarily just to the main breaker output to get the charger going. And figure out the other problems, which he must do.

I have rewired many houses with new services and my own boat, so I know what I am doing.

Stuff like this is a pain for sure to find the problems, which seems to be all the distribution circuits as all of them trip off the breaker. But what is really confusing is why it does not trip on 120vac but only on 220 vac, which makes no sense if it is grounded neutrals, unless the power pedestal is doing some circuit checking.

An AFCI breaker WILL trip off if it detects a shared neutral, (I am not talking of a grounded neutral). Maybe a new GFCI breaker now also detects that, but they did not before.

My own boat has a Square-D panel, which I upgraded to AFCI - GFCI combo breakers. So most of my AC circuits are both AFCI and GFCI protected.

I would suggest to look at the connected devices behind the failing circuit breakers.

[svlamorocha]

240V service in Chile does not have two "hots". It has one hot ("vivo") and one neutral ("neutro") wire, plus a Protective Earth wire. That said, this should not be an obstacle if you do things right.

In order to help further I need to know what type of breaker is the one that tripped. Can you please post photos of the breaker(s) and the female connector in the pedestal?

Originally Posted by mikereed100

I have run into an interesting problem that has me a bit baffled. I am in a marina in 240v Chile with my 120v American electrical system. The dock has 240v service via a 2 prong receptacle. I bought a 2 prong plug and adapted it to my 120v 30 amp 3 prong plug by connecting each of the hot wires from the dock to the hot and neutral wires of my 120v system, reasoning that this should give my 240v at the panel, and it does. I can plug in, turn on the AC main and all is well until I try to throw the breakers on any of my outlets or my battery charger. When I do this the breaker at the base of the dock trips. Nothing is plugged in when this happens. I have tried reversing the polarity of the hot wires and it makes no difference (which, of course, it should not). All of my breakers are "world breakers" by Bluesea and are rated for 250v. All of my wiring is specced for 120v so no worries there. My charger is rated up to 250v as well. My question is: What is my boat doing to anger the breaker at the base of the dock?

[nebster]

Originally Posted by CatNewBee

I read the OP too, and frown about the idea instantly.

No problem, you can frown. But the OP indicates no loads on the circuit, so a lecture on volts and amps is irrelevant here.

On a boat installation can be hidden devices you not even know exist. Like 120V relay, that give shore power priority over inverter or generator, devices plugged in and in standby, A/C units, that are not on, but the electronic panels are connected to be ready to turn on... Any of this can get wrecked or cause the breaker to flip.

Irrelevant. He describes the phenomenon happening on any branch circuit. Presumably, not all of them have "hidden devices" waiting to be destroyed by 240V.

Even some chargers that are able to take different voltages have switches or bridges to configure the input voltage range. Not all are automatic like cellphone chargers.

Irrelevant. His issue occurs without a charger.

It may be feasible to connect a 240V EU yacht to 240V dual phase US omitting the neutral, but it does not work vice-versa with 120V. In the EU there are 5 pin 3 phase outlets with neutral and shield allowing either 3 x 220V to neutral or 3 x 380V between the phases for power applications. I would never try to connect 220V between two phases on those.

I wouldn't either, but the OP asked for help with his problem, not for my judgment about his wiring choices.

[nebster]

Originally Posted by sdowney717

Stuff like this is a pain for sure to find the problems, which seems to be all the distribution circuits as all of them trip off the breaker. But what is really confusing is why it does not trip on 120vac but only on 220 vac

I agree, this is a bit surprising. However, RCDs on large 240V and 120V marina circuits in the USA only became a requirement a few years ago. Perhaps this boat has simply not encountered one? I don't know the prevalence of these in other countries.

[ebs001]

Originally Posted by Jammer

Hi Mike


I usually don't reply in detail to electrical troubleshooting threads, because experience has taught me that it is difficult to help people this way and because some people do not have the background to follow the suggested steps safely.


I'm making an exception.


I would assume that the shore power pedestal has an RCD (residual current device), similar to what we call a GFCI in the USA. These are often a part of the circuit breaker, and a RCD trip is indistinguishable from an overcurrent trip. I'm making the assumption because it fits the facts.


RCDs will trip when the flow in the hot wire does not equal the flow in the neutral. They will tolerate a small difference, somewhere around 20 mA or 50 mA or something like that. The unequal flow occurs when there is leakage current that flows through the ground connection. In many cases, there is a short (deliberate or otherwise) between neutral and ground, somewhere, and so whenever current starts to flow some of it will go through the ground instead of the neutral, leading to an imbalance that trips the RCD.


This can be a problem in the USA, as well, as more marinas are installing RCDs, but not as many as have them internationally.


You find the problem by disconnecting shore power and any other 120v/240v power sources you may have, then connecting an ohm meter between neutral and ground. If it reads infinity, great, otherwise you have leakage, and you have to start disconnecting neutrals in your breaker panel until the meter goes to infinity, then you've found the circuit that poses the problem.


Since the branch circuit breakers don't disconnect the neutral, the problem will appear to occur on all circuits even if the actual short is only on one circuit.


In some cases it may just be wet wiring somewhere rather than an actual short.


Happy hunting

The dock beaker only trips when a branch circuit breaker is turned on. If the leak to ground is on the "neutral" side it would occur as soon as the main was turned on. In the receptacle circuit the OP says there are no connected loads. The leakage therefore has to be the hot wire side and in the wires coming off the load side of the breakers.

[Jammer]

>plonk<


Note to self, never give electrical troubleshooting advice over the internet