115V AC to 230V? Is There a Reasonable Solution?

[Coquina]

Originally Posted by Madehn

ok Many thanks for all of the replies- i now know two things for sure
1) it can be can be done and should not be that expensive
2) i am going to go get a good electrician to do it.

for those that asked - the boat currently has two 115 V 30 amp shore power sockets. One of those runs everything on the boat-- the second is not wired to anything yet- my plan was to use the second one to be dedicated to the AC units exclusively. Sounds like it may be possible to still do that by using a transformer to step up the voltage- going to ask about that first- if that does not work we will look at the problem again. I am fairly competent on most parts of the electrical system on my boat and am comfortable with the inverter, generator, etc but i know nothing about 230 volt power- and as Clint said " a man has got to know his limitations" so i am definitely going to enlist a professional to assist in this part. Thanks again to all of the folks for their thoughtful replies.

You have some options:
1. Get a 240 volt inlet installed instead of the two 120 volt ones. Between that work and a new shore power cord, some $$$$.
2. Get a transformer installed. Some $$$$.
3. Assuming the AC unit has a 120 volt equivalent, sell the one you have and get the 120 volt version. That might be cheapest of all.

[Mike Banks]

Yes--you need about a 2 kva isolating transformer with a step-up from 110 to 240 volts. There is your best solution.

[billgewater]

Any reason the issue of mains frequency has not been discussed? Surely there must be some devices that will preferably operate at either 50 or 60 hertz? E.g. those that tap the mains frequency to run internal clocks .e.g. microwave ovens etc. Induction cookers?

[roland stockham]

Fitting a transformer is the simple way to do this. BUT CAUTION; there are a number of transformers advertised (eg on Amazon and Ebay) that claim high outputs up to 5Kw but if you read the small print that is NOT continuous power and can only be used for 5-10m an hour otherwise the transformer will burn out. May be fine if this is a coffee maker but not for an A/C unit, read the small print and check the duty cycle. Also a transformer only works when connected to the dock. If you want to run the equipment underway or at anchor then it has to be the inverter route and a separate inverter is probably better than trying to integrate it into you existing electrics which get complex and expensive.

[Coquina]

Originally Posted by billgewater

Any reason the issue of mains frequency has not been discussed? Surely there must be some devices that will preferably operate at either 50 or 60 hertz? E.g. those that tap the mains frequency to run internal clocks .e.g. microwave ovens etc. Induction cookers?

Yes - the OP is not dealing with frequency issues that we know of, in the USA we have plenty of 120 volt AC units and plenty of 240 volt AC units too. EU 50 Hz ACs usually do fine on 60 Hz, but some American 60 Hz units do not tolerate 50 Hz very well. Running too slow is hard on the motors.

[KP44]

Two 30 amp shorepower? This sounds like two separate shorepowers, which will only sporadically give both phases - so 240v between the hot sides of a common ground.

Better to get a 50 amp 240v service or use your "dedicated to AC 30 amp" with a step-up converter.
Or get an AC unit that uses 120v power. Sometimes it is better to keep it simple.

[CatNewBee]

Originally Posted by fourlyons

I'm not an electrician, but that's not true here in the US. Here 240 volt supplies are two hot 120 volt legs out of phase, with a third neutral ( and somewhat recently a forth safety ground) making a 4 wire conductor. Overseas in many places line voltage is 230 and a neutral, making a two wire conductor.

Yes, and it is exactly the same, besides they have 50Hz, not 60Hz. And there are 3-phase systems with 5 pole connectors, 3 x 220V between hot and neutral, each phase at 120° from the others, 380V between each pair of phases, the 5th pin is earth. In the us a 2 phase system is common with 180° phase shift, so there is 120V between each phase and ground and 240V between the 2 phases.

[valhalla360]

Are the two 30amp shore power sources on opposite legs of the 240v source?

The best solution is to upgrade to a 50amp-240v source and then run a 240v circuit (assuming you are staying in the USA).

You never answered regarding the amperage draw. This could be an issue even if the 30amp outlets are on opposite sides. If the unit is pulling 15amp-240v, that only leaves you 15amp on each leg for the rest of the boat. A 2nd air/con may wind up popping the breaker regularly when it kicks on and pulls 20-30amp for a second on startup.

[smac999]

Most Likly it’s 230v 50hz. So transformers or getting 240v 60hz from dock is not an option.

If the rest of the boat is 120. Get another unit. Or replace the parts in it with 120v parts.

[markcouz]

Originally Posted by smac999

Most Likly it’s 230v 50hz. So transformers or getting 240v 60hz from dock is not an option.

If the rest of the boat is 120. Get another unit. Or replace the parts in it with 120v parts.

Or get a dedicated 230v inverter which will already be providing power at 50hz, probably cheaper than the transformer route as that would be a chunky monkey.

Unfortunately whatever route you choose to take the "good deal" will be obliterated.

[smac999]

Originally Posted by markcouz

Or get a dedicated 230v inverter which will already be providing power at 50hz, probably cheaper than the transformer route as that would be a chunky monkey.

Unfortunately whatever route you choose to take the "good deal" will be obliterated.

You’d need a big one To run an a/c. You’d also need a few extra chargers to keep up with the inverter load.

[Coquina]

Originally Posted by KP44

Two 30 amp shorepower? This sounds like two separate shorepowers, which will only sporadically give both phases - so 240v between the hot sides of a common ground.

Better to get a 50 amp 240v service or use your "dedicated to AC 30 amp" with a step-up converter.
Or get an AC unit that uses 120v power. Sometimes it is better to keep it simple.

Marinas with two 30 amp outlets are supposed to be wired on opposite legs. Obviously human error creeps in, but wiring the boat for 240 won't solve that issue unless you get the marina to put in a 240v/50a outlet on the dock. Some of our slips at my marina have this, most do not.
I think we might even have one slip wired for 208v 3 Phase 100 amp.

[Suddy]

You didn't specify the amount of current you need at 230 Vac. You also did not specify which market the product was manufactured. If it is for the US market, it is possible that the motor for the compressor and the fan can be modified (sometimes with just rearranging some wires) to run on 120 Vac, but at about twice the current. (Watts matter.) Your choice of going with a "good electrician" is your best bet.

[smac999]

Originally Posted by Coquina

That is not true at all. Deriving 240 volts from 2 120 volt shore power outlets is something done every day all over the USA. A Y adapter or two is a standard thing to carry on boats with 240 volt systems and marinas usually have them as loaners as well.

This used to work. But many us docks are charging their 30a plugs to gfi to meet new electrical code. The y’s no longer work with twin gfi Dock outlets. They just trip.

[KP44]

Originally Posted by Coquina

Marinas with two 30 amp outlets are supposed to be wired on opposite legs. Obviously human error creeps in, but wiring the boat for 240 won't solve that issue unless you get the marina to put in a 240v/50a outlet on the dock. Some of our slips at my marina have this, most do not.
I think we might even have one slip wired for 208v 3 Phase 100 amp.

Some newer marinas have only 50 amp shore power, at least for boats as big as mine. (Mystic is 45' and we often allotted a 50' slip. Our current slip is for a 63' vessel.) We use a splitter because we only need 30 amps at 120v.

The nominal voltages are 120 volts (or 240 volts) at 60 Hz in Canada, the USA, and Mexico. Most of Europe uses nominal 250 volts at 50 Hz. Many modern appliances and chargers will easily tolerate the difference in Hz. Even computers and cell phone chargers often say, "90 - 250 volts and 50 - 60 Hz AC".