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

[Madehn]

is there a simple way to get 230V AC from my 115V shore power connections- i have one AC which i have been waiting to install that needs 230V. I have dual 30 amp 115 volt shore power plugs currently. This is the only piece of the boat that needs this voltage- am i better of to just go get a different AC unit. ( i got a great deal on the unit which i thought was a 115v unit at the time. My fault for not looking closer now trying to rectify my

[markcouz]

What kind of current does the AC unit typically draw?

One simple solution would be to get a dedicated 230v inverter that draws off your batteries and powers that AC unit only.

Otherwise at low power a 115/230v transformer may be the best as it would use shore power directly and not battery.

[CatNewBee]

You also could use 2x115V power outlet and connect the A/C unit only to the 2 phases and not use the common ground, then you will have 230V 60Hz.

You write, you have 2 x 115V 30A, I assume, this is a two phase connector.

Can you post a picture of your outlet contacts?

[tkeithlu]

That's why you got a good deal on it.....

[Siberian Sea]

I just bought 4000 watt power converter unit. Converts 110 to 220 and 220 to 110. The output side of power is cleaner then what what go’s in so its safe for sensitive electronics.

[Coquina]

Originally Posted by Madehn

is there a simple way to get 230V AC from my 115V shore power connections- i have one AC which i have been waiting to install that needs 230V. I have dual 30 amp 115 volt shore power plugs currently. This is the only piece of the boat that needs this voltage- am i better of to just go get a different AC unit. ( i got a great deal on the unit which i thought was a 115v unit at the time. My fault for not looking closer now trying to rectify my

This is a pretty common wiring job. Standard dock outlets with two 30 amp 120 volt outlets should be on opposite legs of the shore transformer, giving you 240 volts between them.
This is not a hard job, but it isn't for a n00b either since getting it wrong can burn your boat down or kill you. A local competent marine electrical shop should be able to handle this. This does raise a question of why you have dual shore power connections now? What do they do now? A photo of your shore power inlets and main breaker panel for AC would go a long way
Also how many BTUs is the air conditioner?

[boat driver]

Easy to solve. But if you are not a competent understanding of power get an electrician to assist. Set up your panel so each cord is a different leg- simpler assurance if using a 50 amp splitter at dock.
The Blue Seas has a diagram and sells light diodes ($6 ea) to use between the legs to show 220va/c.

IMPORTANT-
1) understand that 30 amp cords on a fifty amp splitter on dock must have 30 amp breaker protection on boat end- otherwise you can pull 50 amps thru each cord before tripping (or catching fire)
2) if the dock 30 amp plugs are on the same leg of "the dock power supply" you will not get 220volts-
3) be sure the boat distribution panel is balanced in power use and can accommodate the a/c unit start up needs-
4) put into the panel a reverse polarity as well- again Blue Seas has the diagram and it is easy. home built costs- 4 diodes ((2)green110v for each line, (1)amber240v , (1) red reverse, 1 resistor for reverse polarity rig)) total cost- $27 materials- and two hours labor.

Use of two 30 amp cords vs 50 amp is common for weight and handling of the cords. Particularly on vessels where 220v is only needed for specific or seasonal use. If the boat was wired initially for two cords this may be as simple as confirming and installing two new breakers. BUT CONFIRM IT IS CORRECTLY WIRED. And mentioned while opportunity- be sure boat is wired as a sub-panel to the dock- The increasing requirement of 50 amp GFI on docks requires the grounds and neutrals separated which is a change from historical belief.

[captmikem]

Or just put a 115 - 230 transformer in front of it. Simple solution and you don't have to change anything.

I have one I put on my boat when I spent a year cruising the med. (They work both ways).

M

[sailcrazy]

While a simple 110v/220v transformer MAY work for you-if you buy one near 2x the normal running watts required for the aircon, we've had very BAD luck with them. Our boat is a 230v (Euro/Asia-wired)boat, and we tried 3 of the "ebay special" transformers....none of them lasted more than a couple of weeks. We ended up buying and installing a Victron Auto-isolation transformer, and installing it on the incoming shorepower line. If the incoming power is 110, the transformer senses it and auto-transforms it into 230v for the boat. If it sees 230v coming in (Europe, Asia, and most of the world), it bypasses itself and the boat sees 230v AC. It's worked great now for 4 years!

[kish]

Originally Posted by Madehn

is there a simple way to get 230V AC from my 115V shore power connections- i have one AC which i have been waiting to install that needs 230V. I have dual 30 amp 115 volt shore power plugs currently. This is the only piece of the boat that needs this voltage- am i better of to just go get a different AC unit. ( i got a great deal on the unit which i thought was a 115v unit at the time. My fault for not looking closer now trying to rectify my

The simplest method and safest method is to buy an isolation transformer 230 volt / 115 volt with a rating (KVA) suitable to run your air conditioner. To allow for motor starting, a transformer rating compatible with motor starting is essential.

This is the method used by US boats that come to 230 volt marinas in Europe.

Aggregating two 115 volt inputs won't work ,
One leg of a 230 volt supply has to be connected to supply neutral, impossible if you use 2 x 115v hot connections.
Competent and reliable electricians are a rare species.

[Coquina]

Originally Posted by kish

The simplest method and safest method is to buy an isolation transformer 230 volt / 115 volt with a rating (KVA) suitable to run your air conditioner. To allow for motor starting, a transformer rating compatible with motor starting is essential.

This is the method used by US boats that come to 230 volt marinas in Europe.

Aggregating two 115 volt inputs won't work ,
One leg of a 230 volt supply has to be connected to supply neutral, impossible if you use 2 x 115v hot connections.
Competent and reliable electricians are a rare species.

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. You can go 1 240 volt cord to 2 120 outlets and you can go 1 240 volt outlet to 2 120 volt cords.
The other thing to keep in mind is past a certain BTU level, an air-conditioned is going to be blowing a 30 amp shore power breaker at 120 volts. There is a practical upper limit to how big an AC unit can run on 120. A transformer does nothing to solve this issue, besides for being large and expensive.
I used to do boat wiring and install marine air conditioners for a living, so this is not a new issue to me.
EDIT - We never did put 2 120 volt connections on the boat end unless they were independent. We would put a 240 volt shore power inlet on the boat end and you could run one cord to the dock and Y from there if needed. We did do a number of boats with one 120 volt cord for the boat and one more for the air-conditioning that were independent. That way the AC unit could have the full 30 amps and not blow the breaker when the water heater came on.
Combining the two to 240 volts with two boat shore power inlets can leave you with live exposed metal.
This connects the 240 volt shore power cord to 2 120 volt outlets:
https://www.westmarine.com/buy/marin...57?recordNum=1

[oleman]

The normal way for AC voltage step up or down is a transformer. It also give complete isolation input to output. This is the primary reason why mains power is AC in the first place.

[fourlyons]

Originally Posted by kish

The simplest method and safest method is to buy an isolation transformer 230 volt / 115 volt with a rating (KVA) suitable to run your air conditioner. To allow for motor starting, a transformer rating compatible with motor starting is essential.

This is the method used by US boats that come to 230 volt marinas in Europe.

Aggregating two 115 volt inputs won't work ,
One leg of a 230 volt supply has to be connected to supply neutral, impossible if you use 2 x 115v hot connections.
Competent and reliable electricians are a rare species.

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.

[cyan]

Originally Posted by kish

Aggregating two 115 volt inputs won't work ,
One leg of a 230 volt supply has to be connected to supply neutral, impossible if you use 2 x 115v hot connections.
Competent and reliable electricians are a rare species.

Incorrect, as others have stated. This erroneous paragraph does end ironically, though, with saving grace.
There are, of course, caveats and conditions for safely using two 115v inputs to get 230. However, more fascinating to me is the amount of incorrect free advice regarding dangerous systems such as main AC power. Different systems in each country explains some but not all of the wrong words. I’ve read stuff on CF that is wrong enough to kill. An answer rating button might be really helpful in discarding the bad stuff.

[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.