Running a 120 volt american yacht off 240v

[Paul71]

Well my boat has the 50 amp setup as its over 50 ft and everything is electric! So the shore power cable has 2 120 lives. I have a 32 amp cable and a 5 kva transformer.
Is it possible to split the lives off the transformer to power the 2 120v legs in on the plug to the boat?
Paul

[capt jgw]

You don't have to rewire the boat going from 120 to 230/240. The wires will all be larger gauge than required for 240 which is fine. It's going the other way you can't do, wiring spec'ed for 240 running 120 volts will be half the gauge required and would probably burn down the boat. But you would still have to replace all the appliances and outlets. So unless you're planning on doing that anyway, the other fixes mentioned here would be more practical.

[goboatingnow]

Originally Posted by capt jgw

You don't have to rewire the boat going from 120 to 230/240. The wires will all be larger gauge than required for 240 which is fine. It's going the other way you can't do, wiring spec'ed for 240 running 120 volts will be half the gauge required and would probably burn down the boat. But you would still have to replace all the appliances and outlets. So unless you're planning on doing that anyway, the other fixes mentioned here would be more practical.

Actually that’s not true. Most European boats will be wired with 2.5mm2 cable , that’s actually sufficient under the ABYC code for most 110vac circuits

[donradcliffe]

Originally Posted by goboatingnow

Actually that’s not true. Most European boats will be wired with 2.5mm2 cable , that’s actually sufficient under the ABYC code for most 110vac circuits

Nope.

https://www.multicable.com/resources...ce-awg-to-mm2/

[shimari]

Originally Posted by goboatingnow

Actually that’s not true. Most European boats will be wired with 2.5mm2 cable , that’s actually sufficient under the ABYC code for most 110vac circuits

This is correct. The circuits on our 2018 boat built in the UK are wired with 2.5mm2.

[ka4wja]

Paul,
1) You, of course, do not need to rewire your boat.


2) And, if you wish to run air-conditioning and/or heat-pump heating (reverse-cycle air-cond), then make sure that your 120vac motors running the compressor, blower, and raw-water-circulating pump will all run on 50hz/60hz....the good news is many older ones (as I have) are spec'd for 50hz/60hz....the bad news is that some "newer" air-cond units sold in US are spec'd at 60hz...you should have a look at yours!
Of course, you can run a 60hz motor on 50hz, but it won't run efficiently (it will be slower, hence your air cond won't cool as effectively) and usually will run hotter, thereby reducing its longevity. {note: as far as I know, if your "heat" is forced-air, electric-heat-strip / resistive-heating, then the 50hz issue is less / un important.}


3) A large step-down transformer (especially a multi-tap transformer) is your best, least expensive approach....

I cannot fathom running air-cond off inverter(s) and a large charger running on 230vac shore power, continously...but, if you must have 60hz power, this is the most economical way...



4) Even better news, these subjects have already been discussed here....and solutions covered in great detail, including sources. Which is great for those heading your way soon, and would like a solution on-board upon arrival (as it's a lot cheaper to equip here in US)...

Have a look here:

"110v boat in Europe"
https://www.cruisersforum.com/forums...pe-172133.html

"220 vs 110 Volts..."
https://www.cruisersforum.com/forums...ts-148603.html

"110vac to 220vac Conversion Revisited"
https://www.cruisersforum.com/forums...ted-38004.html

And, of course, Jack Tyler's wonderfully-written treatise on this:
European Power Onboard



5) Also, we are assuming that your USA "240vac" shore-power is in-fact split on-board into two 120vac services? Meaning that you do not have appliances on-board that natively run off 240vac? If that were the case, that you had some 240vac appliances, then we need to discuss further....but, as long as our assumptions are correct (everything running on AC, you have on-board, is 120vac), than all above applies.


6) Here are photos of my 48lbs (yes, it is HEAVY!), 5Kw / 5000 watt (4kw / 4000 watts continuous) transformer....sitting in my cockpit...{note these are watts / kw, not va or kva....which can be used as advertising/marketing ploy, as kva is ~ 80% of kw...}
I didn't need a permanent solution, just a temporary one....otherwise, I'd have mounted/secured this in my lazarette and wired it accordingly
{I have a 3rd "shore inlet" on the transom that was originally for TV and Telephone connections, but it is the same size as a standard Marinco shore-power inlet, so I could simply add a 230vac EU inlet there and wire the transformer permanently....but, no need for my application of just a few days / a week in marina}...







I hope this helps. (if not, please provide more info / more details with your further query)

Fair winds.

John


P.S. Just wondering why this is in the "Marine Electronics" sub-forum, as it seems to be better suited-to the "Electrical: Batteries, Generators & Solar" sub-forum?

[shimari]

Originally Posted by ka4wja

...

2) And, if you wish to run air-conditioning and/or heat-pump heating (reverse-cycle air-cond), then make sure that your 120vac motors running the compressor, blower, and raw-water-circulating pump will all run on 50hz/60hz....the good news is the older ones (as I have) are spec'd for 50hz/60hz....the ban news is that most "newer" air-cond units sold in US are spec'd at 60hz...

...

My newer AC and circulation pump both run at 50hz and 60hz. My previous boat's (2007) aircon only ran at 60hz. I think it's a YMMV situation and some owners will get lucky and others won't.

[ka4wja]

Shimari,
You're correct....and, you caught my error before I corrected it above....(I did correct it)

Originally Posted by shimari

My newer AC and circulation pump both run at 50hz and 60hz. My previous boat's (2007) aircon only ran at 60hz. I think it's a YMMV situation and some owners will get lucky and others won't.

Fair winds.

John

[goboatingnow]

Originally Posted by donradcliffe

Nope.



https://www.multicable.com/resources...ce-awg-to-mm2/

Yes so

In actual comparison 2.5mm2 is actually a bigger conductor cross section then AWG14 ( which is 2.08mm2) it’s more like AWG13 , which doesn’t exist.

ABYC e11 suggests single wires of AWG 14 are suitable for 20 A , or 2200W at 110VAC and in fact 2.5mm2 could safely carry 25A at 110 , or 2750W. This wiring is therefore more then suitable for general purpose 110 vac circuits with the exception of a few special circuits

[Paul71]

Originally Posted by ka4wja

Paul,
1) You, of course, do not need to rewire your boat.


2) And, if you wish to run air-conditioning and/or heat-pump heating (reverse-cycle air-cond), then make sure that your 120vac motors running the compressor, blower, and raw-water-circulating pump will all run on 50hz/60hz....the good news is many older ones (as I have) are spec'd for 50hz/60hz....the bad news is that some "newer" air-cond units sold in US are spec'd at 60hz...you should have a look at yours!
Of course, you can run a 60hz motor on 50hz, but it won't run efficiently (it will be slower, hence your air cond won't cool as effectively) and usually will run hotter, thereby reducing its longevity. {note: as far as I know, if your "heat" is forced-air, electric-heat-strip / resistive-heating, then the 50hz issue is less / un important.}


3) A large step-down transformer (especially a multi-tap transformer) is your best, least expensive approach....

I cannot fathom running air-cond off inverter(s) and a large charger running on 230vac shore power, continously...but, if you must have 60hz power, this is the most economical way...



4) Even better news, these subjects have already been discussed here....and solutions covered in great detail, including sources. Which is great for those heading your way soon, and would like a solution on-board upon arrival (as it's a lot cheaper to equip here in US)...

Have a look here:

"110v boat in Europe"
https://www.cruisersforum.com/forums...pe-172133.html

"220 vs 110 Volts..."
https://www.cruisersforum.com/forums...ts-148603.html

"110vac to 220vac Conversion Revisited"
https://www.cruisersforum.com/forums...ted-38004.html

And, of course, Jack Tyler's wonderfully-written treatise on this:
European Power Onboard



5) Also, we are assuming that your USA "240vac" shore-power is in-fact split on-board into two 120vac services? Meaning that you do not have appliances on-board that natively run off 240vac? If that were the case, that you had some 240vac appliances, then we need to discuss further....but, as long as our assumptions are correct (everything running on AC, you have on-board, is 120vac), than all above applies.


6) Here are photos of my 48lbs (yes, it is HEAVY!), 5Kw / 5000 watt (4kw / 4000 watts continuous) transformer....sitting in my cockpit...{note these are watts / kw, not va or kva....which can be used as advertising/marketing ploy, as kva is ~ 80% of kw...}
I didn't need a permanent solution, just a temporary one....otherwise, I'd have mounted/secured this in my lazarette and wired it accordingly
{I have a 3rd "shore inlet" on the transom that was originally for TV and Telephone connections, but it is the same size as a standard Marinco shore-power inlet, so I could simply add a 230vac EU inlet there and wire the transformer permanently....but, no need for my application of just a few days / a week in marina}...







I hope this helps. (if not, please provide more info / more details with your further query)

Fair winds.

John


P.S. Just wondering why this is in the "Marine Electronics" sub-forum, as it seems to be better suited-to the "Electrical: Batteries, Generators & Solar" sub-forum?

Hi John, Thanks for your post! Well it's an old 56ft motor yacht and runs 50 amps. When the generator is running (25kva) it shows 240v incoming on the guage the 2 bottom guages show 120v each so obviously split or step down. I have a shore cable with 2 120v lives and a neutral and earth this is where I'm struggling to fathom out how this is done via a transformer as there is 2 lives going in. Black magic to me!
Paul

[Paul71]

Originally Posted by Paul71

Hi John, Thanks for your post! Well it's an old 56ft motor yacht and runs 50 amps. When the generator is running (25kva) it shows 240v incoming on the guage the 2 bottom guages show 120v each so obviously split or step down. I have a shore cable with 2 120v lives and a neutral and earth this is where I'm struggling to fathom out how this is done via a transformer as there is 2 lives going in. Black magic to me!
Paul

Do you do WhatsApp? My number is 07895267352

[ka4wja]

Paul,
1) No whatsap, no messenger, no facebook, no instagram, no tictok, no snap chat, no facetime, no etc. etc. etc....
Most (all ?) of this is covered in those links....


2) USA "240vac" service is TWO 120vac "hot" lines, with one common-neutral (and, in some designs one additional wire as a "ground" or "earth" wire)....so, you see 240 volts across the two "hot" lines, and 120 volts across either "hot" line and "neutral"....
Not black magic at all, but I understand that a bit confusing for laypersons and/or those in UK/EU who don't have experience with USA electrical power...
[note that these "nominal" voltages are now-a-days typically ~ 240 - 250vac...and hence 120 - 125vac....and, usually anything from 220-250 / 110-125 is usable on-board, with the higher end of those ranges preferred.]

UK / EU "230vac" service is ONE 230vac "hot" line and one neutral and one ground...
[in years past, I've seen anything from ~ 210vac to ~240vac at dock pedestals in EU marinas....but, usually these days you'll find pretty close to 230 - 235vac...btw, someone in EU marina right now can correct me or clarify/confirm this, as I'm in Florida at the moment]

You CANNOT connect UK/EU 230vac service to a USA 240vac system....it will NOT work, and will likely blow breakers and damage equipment!!!

So...

So, you need to "transform" (using a "transformer") the 230 volts +/- a few volts --- down to 115vac +/- a few volts, and connect this lower voltage output to your USA "120vac" inlets....

This usually takes care of everything (assuming what AC-powered equipment / gear you have works well / acceptably on 50hz....you will need to look at your equipment, as nobody else is there, it is up to you...)

If you have some native 240vac appliances on-board (we don't know, 'cuz you haven't stated), then things get more complicated but still do-able with two transformers, although at this point it's best to consult a UK/EU electrician, and you may find using inverters / chargers to be just as inexpensive / effective?




3) BUT...As I wrote, we (or maybe I should just say I am) assuming something here...

5) Also, we are assuming that your USA "240vac" shore-power is in-fact split on-board into two 120vac services? Meaning that you do not have appliances on-board that natively run off 240vac? If that were the case, that you had some 240vac appliances, then we need to discuss further....but, as long as our assumptions are correct (everything running on AC, you have on-board, is 120vac), than all above applies.

And, when you write:

Originally Posted by Paul71

Hi John, Thanks for your post! Well it's an old 56ft motor yacht and runs 50 amps. When the generator is running (25kva) it shows 240v incoming on the guage the 2 bottom guages show 120v each so obviously split or step down. I have a shore cable with 2 120v lives and a neutral and earth this is where I'm struggling to fathom out how this is done via a transformer as there is 2 lives going in. Black magic to me!
Paul

This re-enforces this assumption, but it does not answer the questions:

Do you have any "240 volt" appliances on-board?
Air Cond?
Domestic hot water?
Electric Range / Stove / Cook-top / Oven?
Heaters?
etc..
Do any of the above run on 240vac? (or anything on-board?)

Until you answer these, there's little more I can do.


Fair winds.

John

[Paul71]

I will have a look at the a/c heating and stove and hot water cylinder and get back to you on that.

[Paul71]

Hi John, I've checked everything aboard and it's all 120v.
So am I able to use a transformer with a single feed from ashore 240v (32amp) to the transformer then is it two outlets 2 X 110 from the transformer into a Y then into the boat?
Paul

[goboatingnow]

Just to be clear

USA 220/240 vac is a split phase supply. There is no equivalent in 230 vac land.

However European 230 vac will power US 240 vac appliances. In Europe the neutral can be grounded or floating depending on country

Note that despite what was said a European 230 vac boat can be run from a US split phase 240 vac system simply use the two hot wires. However for safety you need double pole AC breakers and you need to remember the neutral is now hot.

However assuming the neutral isn’t hot is a bad idea in Europe anyway