240 volt from two 125’s using a splitter

Staying in Montauk NY for a month and having a real issue with my electrical power needs. Marina has mostly 125v 30 amp power towers. The few 50 amp towers only produce about 200 to 210 volts on my panel and a/c units shut down flashing low voltage . I purchased a Hubbell splitter with the box that the two 30 amp plugs go into and then comes out with a single 50 amp plug to connect my shore cable to. According to my research before buying this expensive splitter, It’s supposed to boost my power to 250v but still only 30 amp which I could live with. When I plugged it in my panel showed only 200volts. Anyone ever have this problem that could suggest a solution. Going to get very expensive running my generator to make 240 volts for a/c and it’s getting hot up here. I put a test meter into the two 30 amp plugs in one tower and get 125v to 130v from each outlet but my panel voltmeter reads about 200 or 210 volts. Going to test voltage coming out of splitter box tomorrow and see if maybe another tower will have better voltage.

First question before I answer, do you have a 50/125/250 plug on your boat?

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Originally Posted by Sea Horse

Staying in Montauk NY for a month and having a real issue with my electrical power needs. Marina has mostly 125v 30 amp power towers. The few 50 amp towers only produce about 200 to 210 volts on my panel and a/c units shut down flashing low voltage . I purchased a Hubbell splitter with the box that the two 30 amp plugs go into and then comes out with a single 50 amp plug to connect my shore cable to. According to my research before buying this expensive splitter, It’s supposed to boost my power to 250v but still only 30 amp which I could live with. When I plugged it in my panel showed only 200volts. Anyone ever have this problem that could suggest a solution. Going to get very expensive running my generator to make 240 volts for a/c and it’s getting hot up here. I put a test meter into the two 30 amp plugs in one tower and get 125v to 130v from each outlet but my panel voltmeter reads about 200 or 210 volts. Going to test voltage coming out of splitter box tomorrow and see if maybe another tower will have better voltage.

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I did what you said..... two 30's to one 50 and it worked, but only 30 A. My dock only has 208V but
the 30A sockets do put out about 120+V ea. I know very little about electricity but when I need help
I call my friend Alec....trician. I bought a voltage booster from Wards in Ft. Lauderdale and it worked
great. Fairly pricey but worth it.. Since then I discovered that there is a way to boost your power
intake by switching a few wires in your isolation transformer (which most Hatteras' have). You can
search this forum for old threads on how to do it...

Walt

Of all the places I ve travelled the NE always had the fewest 50 amp service.

The expensive Smart Y will not change voltage, it only lets you get 220/240 service from a pair of 30 amps outlet but only if they are on opposing phases. Not always the case...to boost voltage at crappy marinas you need a boost transformer as awakt suggested. Maybe worth buying and reselling later...

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Originally Posted by SEVEN

First question before I answer, do you have a 50/125/250 plug on your boat?

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I have one 50 amp power cable that can be plugged in to Shore 1 or Shore 2. Depending on which side I plug in I then flip breakers on distribution panel to reflect my choice. Hope that answers your question.

If it were 50/125/250 I could help. Sorry

I don't think the SMart Y device has a transformer in it, which is what you need. Reconnecting the iso transformer might help, as noted already. The larger Hatteras yachts had/have them.

Just install a boost switch on your isolation transformer and you can boost that 208 to 240. You can use the 50amp plug that way with no need for splitters/combiners.

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Originally Posted by SKYCHENEY

Just install a boost switch on your isolation transformer and you can boost that 208 to 240. You can use the 50amp plug that way with no need for splitters/combiners.

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Sky, can you elaborate? We only get 208 at our dock and I'd like to boost it.

Just in case anyone wants to know I’ve gotten an explanation of what’s going on with the power issue I’m having.Basically I’m screwed. The Hubbell YQ230 splitter I purchased was a total waste of money and won’t increase voltage going to my boat. The marina only has 220v “Y” power which comes out of the box at about 208 volts. Plugging into two 30 amp 125 V power will not give you more than 208 volts just like plugging into the 50 amp dock outlet may give 50 amp service but still only 208 volts. I have no idea why they make and sell this device and feel like I was taken since it clearly says on the splitter that it will take two 125 v lines and boost it to 240 v with 30 amp service but higher voltage. Possible in another situation it could be helpful but unfortunately not in my case. My research indicates some newer boats have a type of transformer installed that will recognize the lower voltage and boost it to 240v. My boat does not have this transformer so only way for me to get 240 v at this particular marina is to buy a power booster for over $1000.00 or more. Options for me at this point is to move to a marina with 240 v shore power or run the generator to use air conditioning when needed. I have come across this issue before when traveling but now understand why I can’t always get 240 shore power at older marinas that usually don’t accommodate vessels requiring 240v 50 amp service. In the future if I’m planning an extended stay I’ll do my homework better than I did this time. Trying to maintain a half full instead of half empty cup ,weathers been great and time spent with family and grand kids is well worth the inconvenience. Thank goodness I’ve got two gen sets so it’s all good when the heat requires A/C.Thanks to all for your input and help.

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Originally Posted by Sea Horse

Plugging into two 30 amp 125 V power will not give you more than 208 volts just like plugging into the 50 amp dock outlet may give 50 amp service but still only 208 volts. I have no idea why they make and sell this device and feel like I was taken since it clearly says on the splitter that it will take two 125 v lines and boost it to 240 v with 30 amp service but higher voltage.

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Just a mathematical observation: 125 + 125 = 250. So 240 would not be a "boost."

You're misreading what the product says. All it can do is combine two opposing phases of 125V. It's not a booster or transformer. It's only capable of doing what already exists in a 250V 50A power supply. It's made for situations where a marina doesn't have 50A service, but you can find two opposing 30A services and combine them. The device also prevents you from pushing 60A (30+30=60) through 50 amp wiring and starting a fire.

Your marina's problem is that it's using two phases from 3 phase power which are not perfectly opposed, whereas single phase 250 has two legs that are perfectly opposed so you get full voltage when you combine them.

P.S. Don't ask how three legs of power is three phase and two legs is single phase. I find it very frustrating too.

208 is normal between 3 phase power legs and common in commercial installations. If there using single phase (less common and more expensive to build out) you would get 240 between the 2 legs.

Most hatts in that size have a transformer in the system. It can be rewired to do what you need if it's there. Look again or call hatteras to see if it was or was not installed.

Interesting that you have two gensets on that boat. Or did you trade up to a larger Hatteras yacht?

If you have run into this problem before, maybe the boosting transformer isn't such a bad idea. Easy for me to spend your money, of course, but if it has been a frequent problem, it might be worth a second look.

Before spending the money for a boost transformer (which I did), be sure you have an isolation transformer
on your boat and have a competent marine electrician set it up with a switch so you switch between
208V and 240V. Right now it's obviously set at 208, as was mine but from what I have learned on this
forum, it's not too difficult to switch to 240v by moving some wires to different poles. I think a selector
switch is absolutely necessary however as you may stop at a marina with the 240v availability and if
your transformer is rigged wrong you will actually get much more than 240v and plenty of trouble$$$.
I remember some years ago someone posted the instructions for rigging your isolation tranformer to
allow switching between 208 and 240. It may have been Sky...

Walt

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Originally Posted by Boatsb

208 is normal between 3 phase power legs and common in commercial installations. If there using single phase (less common and more expensive to build out) you would get 240 between the 2 legs.

Most hatts in that size have a transformer in the system. It can be rewired to do what you need if it's there. Look again or call hatteras to see if it was or was not installed.

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Just to clarify and back up what Scott is saying and help dispel a myth everyone needs to know that you just don't add the two low legs together and that will be your single phase voltage between. It seems that simple but its not. It depends on the utilities transformer supplying the power. You can have 2 120 VAC circuits with only 208 between them. You can also have 2 110/115 VAC circuits with 240 between them. Mine is almost 250 at my house.

And sorry Sea Horse, it was a waste of $ because all that splitter is good for is taking when only 2 30 amp plugs are available and bringing it in as single phase 208/230/240 into the boat. It is at least as good for that if needed.

Another twist just so all can understand it is what the utility is suppling is out on Long Island NY there is what is called a "hot leg". They bring in 3 phases. 2 are 120VAC to neutral. 3rd is 208 to neutral. Not sure but I believe they also bring in 2 hot legs with 1 120 and other 208 to neutral.

CLEAR AS MUD! Other issues are long undersized cables and junctions to account for voltage loss.

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Originally Posted by Oldlaxer1

Sky, can you elaborate? We only get 208 at our dock and I'd like to boost it.

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This thread explains how to add a boost switch to your transformer:

https://www.samsmarine.com/forums/sh...ST+TRANSFORMER

To clarify:

1) Boats without transformers do not have a problem with 208v service on anything that is run off of a single pole breaker. That is because the voltage from any one leg of 3 phase 208 to neutral gives you 120v. That same boat will only have 208v on double breaker loads that would normally run on 240v.

2) Since the isolation transformer "makes it own" power and does not use the neutral from shore, it will only produce half of the input voltage on the same single pole loads. So, you get 104v when plugged into 208v service. This is what most people notice.

3) If you wire a boost switch to the transformer, you switch to different length windings on the transformer so that the input and output voltage is not the same. On our transformers, you can boost the output by about 15%. So, the 208v in becomes 240v out or 120v on each leg.

4) When you do use the boost, you also lower your total amperage available by 15%. So a 50 amp service will only provide 43 amps. But that is what you always get when you use a 208v input no matter if you boost or not.

Sky is also correct because only X Watts are available based on line voltage and amps. Doesn’t matter how you use it after it leaves the source (shore connection). I will admit with all my experience that it’s still confusing on how the amp load available works on single phase between two hots and then 3 phase. Know how to do it for energy calcs but not clear on how it works for overcurrent. Lots of good knowledge here so that helps a lot.

There is a reason why when someone has a weird electrical issue many just respond with call an expert because that is what is needed. Do this stuff every day with BMS and sub metering but I am still an amateur. That means I know just enough to be dangerous.

I'm not an electrician and don't claim to be an expert on this issue. But, I have wired several of these boats with boost switches and they work well. All of them had the same transformers wired the same way. And everyone has been very happy with the results.

What marina are you at in Montauk? I usually stay at Star Island and have no problems with 50a. It may be worth switching where you stay.

Here is a drawing from Hatteras for my transformer.

I’m staying at Offshore Sports Marina. Problem with many marinas here in Montauk is they were built in the 50’s when a bog boat was 40 ft and few if any had A/C. As the folks buying boats started going bigger and bigger with washer dryers, four A/C compressors etc. the power requirements dramatically increased. I’m the only boat here with power issues and can’t expect the marina to bring in a bigger transformer for one boat. This marina made a decision this spring to give up a few slips and move pilings for the 16 to 20’ beam vessels but didn’t consider the power needs of the bigger boats. I grew up here and return every summer to spend time with family. This is not the place I grew up and cost of everything is crazy from fuel prices to dockage to restaurants. This marina was the only one that would take me for 8 weeks and not require a full seasonal rental that averaged from $10,000 to $14,000. I’m not complaining just trying to understand why I’m having power issues. Bottom line is 208V is all their capable of supplying at this time. Now that I understand the problem I’m ok with trying to work around sone of the challenges of less voltage than I require. Just found out my A/C SMX11 can be set to register and shut down for low voltage and had the tec reset salon unit. Works fine and just use it when it gets hot in the afternoons. I can always run one of my two gen sets if I require better voltage. Now I’ll know for future travel including Bahamas that occasionally I’ll have to deal without all of the amenities we become used to. Sleeping with hatches open at night isn’t the worst thing.Appreciate everyone’s responses. I can always depend on those who have been there done that to jump in and try to help. Best site ever for help.

Actually in Fl and Bahamas most slips have 50amp service and even 100amp or twin 50a on Tee heads and larger slips. Needing a smart Y to connect to twin 30a is mostly a NE thing

Agree Montauk has changed. I've been going there for 30 years, I even got married on Star Island. Every year it gets more and more upscale. Still a great place to catch fish!

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Originally Posted by cenger

Agree Montauk has changed. I've been going there for 30 years, I even got married on Star Island. Every year it gets more and more upscale. Still a great place to catch fish!

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Friend passed through the little marina at Orient and said it has been sold to one of the big boys. Stand by for condo's and $3000/month slips.

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Originally Posted by tonytrakovich

Here is a drawing from Hatteras for my transformer.

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I can't read it at that resolution but it looks like it says Polarization transformer. The Polarization transformers were typically on the smaller Hatts. They are not isolation transformers and do not have the capability of boosting voltage.

Call sailor man, I purchased a used portable wards booster from them for $350.00. Works great. They had a few in stock, You just plug it in line on your power cord.

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Originally Posted by SKYCHENEY

I can't read it at that resolution but it looks like it says Polarization transformer. The Polarization transformers were typically on the smaller Hatts. They are not isolation transformers and do not have the capability of boosting voltage.

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That is the drawing that Hatteras sent me. This was for a 1989 65MY stretched to 78. My transformer did have the taps on the secondary. I believe that the only difference between polarization and isolation is the way the grounds are connected.

My 1983 61CMY has similar drawings with no option to use 120v. I have two polarizing Jefferson transformers, with taps that can boost secondary voltage on boat. I have used a club dock every year with 208v which my AC compressors do not like and possibly fried one. Since then I wire one transformer to boost when planing visit to 208v dock. That way I got both covered. Not ideal as have to manage to avoid high electrical loads on boat especially at the 208v docks until changed back to normal. Need to install switches to change over but keeps slipping down the to do list. A true isolation transformer has an internal shield which is attached to shore power ground only. The transformer case should be part of the boats ground system only. I seem to remember some fierce debate on a cruising forum years ago about which is the safer setup in the event of ground failures.

With a polarizing setup, you need to install a galvanic isolator.

No galvanic isolator. She is as built by factory, original thru hulls, running gear all stay all in good condition. Zincs last two years between bottom jobs, apart from on trim tabs which are not bonded.