Rewiring a UK boat to USA specs

[Cheechako]

I wonder how many amps that 8000 btu draws? Not even 10 amps I imagine. For that your existing wiring is fine ....right? just convert to 120v using the existing wiring. Put in an acv master breaker to limit what you can draw. Maybe 15 amps or 20

[s/v Jedi]

Hope this helps you. This is the best way I can come up with, being an electric/electronics engineer and lifelong sailor.

Note that there is something to do with the grounding of the Neutral wire. You probably want to ground the center tap on the auto-transformer which creates the new Neutral for 120V/60Hz service. Much depends on how the rest of the boat/electric installation is done. As long as the isolation transformer is there and installed correctly, the installation is very safe.

[Lowcountry]

S/V Jedi, thank you so much for taking the time to draw this schematic! I will pass this along to whoever I end up hiring to do the job, as I am seriously unqualified for such serious modification. Any other input is greatly appreciated.

[mjscottinnc]

Originally Posted by Lowcountry

S/V Jedi, thank you so much for taking the time to draw this schematic! I will pass this along to whoever I end up hiring to do the job, as I am seriously unqualified for such serious modification. Any other input is greatly appreciated.

If you go the step up transformer route, make sure you get a transformer which has a center tap secondary. Attach the center tap to ground, that way you will have 120 volt from center tap to each of the two phase output and have 240 from phase to phase. Normal for US power, just like most US homes.

[jmschmidt]

There is a device called a "Smart Y" we bought for our French flagged Leopard 47. Works fine at most US marinas. Just can only run one AC load group at a time, so only salon or cabin aircon, but not both and only port or starboard water heater but not both, while at the dock. The aircon didn't seem to mind the 60hz and water heaters don't care either.

We looked at big, heavy and heat generating transformers which we gave up on. And then there was the wire size issue between US and the 240v 50hz world.

[s/v Jedi]

Originally Posted by mjscottinnc

If you go the step up transformer route, make sure you get a transformer which has a center tap secondary. Attach the center tap to ground, that way you will have 120 volt from center tap to each of the two phase output and have 240 from phase to phase. Normal for US power, just like most US homes.

No, don't do that. See the schematic I posted. You only want to ground a neutral at the power distribution panel, where a new neutral is created with an auto transformer.

[s/v Jedi]

Originally Posted by jmschmidt

There is a device called a "Smart Y" we bought for our French flagged Leopard 47. Works fine at most US marinas. Just can only run one AC load group at a time, so only salon or cabin aircon, but not both and only port or starboard water heater but not both, while at the dock. The aircon didn't seem to mind the 60hz and water heaters don't care either.

We looked at big, heavy and heat generating transformers which we gave up on. And then there was the wire size issue between US and the 240v 50hz world.

No the smart Y is of no use because it can not change the 60Hz shore power into 50Hz power. Many items won't run right, if at all. Yes there are air conditioners that will work on either and I highly recommend those as suggested in the diagram I posted above.
This is not something that can be done with a little adapter cable and implementing my diagram does cost money. But it also provides many additional benefits like safety aboard (isolation transformer), safety for the boat's under water metals (isolation transformer), safety for swimmers around the boat (isolation transformer), redundancy (additional inverter/charger) and both 50- and 60Hz aboard that can be used simultaneously

[Sailing Drummer]

I'm surprised no one has mentioned that the US 220/240 is not wired like the U.K. 230. In the US it's 2 phases of 120v (I'm not an electrician so I might not have the terminology right) and in the U.K. It's only 1 phase. I would think that makes a big difference????

[flyingfin]

Originally Posted by Crown Royal

I have helped do a couple boats and we did them all a bit different the main thing that helps the most is that all marinas in USA have 230v available at most of their well now. The trick is the special cord you need to get.

This is not just wrong information, it is DANGEROUS! I do not know of a single marina in the US where you can pull 230V from a two wire+ground system. Suggest you research how a US 120/240V -60cycle wiring differs from a european 230V-50 cycle system. Here is a good place to start

https://www.bluesea.com/support/arti...pean_AC_Panels

[artisanmach]

I think Jedi was pretty clear on US/EU wiring differences.

[Crown Royal]

You can keep all 230 volt devices running as is and use a step down transformer for outlets 50/60 htz won’t notice difference motors will run faster on 60 as they did on 50

[Crown Royal]

The standard 50 amp service is 230 volt on the pedestal

[duncan_ellison]

Lowcountry: It was briefly mentioned somewhere above, but just to re-iterate. A 220V wired boat has very thin AC wiring compared to a 110V wired boat.

The reason is quite simple - more volts = less amps so standard European wiring looks remarkably thin compared to US wiring.

If you compare a US Marinco shore power lead with what we commonly use in the UK for shore power connection, you would be shocked ;-)

So ... don't be tempted to use any of the existing wiring on 110V unless you de-rate the loads by at least 50%.

There's a load difference between 50Hz and 60Hz mains as well, but I'm just trying to get the general message over. Re-wiring with or just using nice fat US cable = good; using existing cabling on 110V = potentially very bad.

[s/v Jedi]

If you check my diagram you'll see that the tricks I used are:

- use a 220-240V 50/60Hz water heater (most are)
- use a 220-240V 50/60Hz air conditioner (search and you'll find)
- use a transformer to always create a 220-240V input (even from 110V if needed)
- use an auto-transformer to create 120-0-120V US service from a simple 240V
- use one inverter-charger programmed to invert at 50-Hz
- use a second inverter-charger programmed to invert at 60-Hz

Now, if you have a 50Hz boat and:

sailing/anchored: have input breaker for 50Hz inverter/charger set to ON so that generator power is used to charge the batteries and also switched to the distribution panel. The input breaker fort the 60Hz inverter/charger is switched OFF so that it is forced into 60Hz invert mode. Your 60Hz outlets are being fed from the battery bank (which is charged by the other inverter/charger)

docked at a 50Hz dock: same as sailing/anchored above.

docked at a 60Hz dock: breaker for 50Hz I/C is switched OFF so that all 50Hz service comes from the battery bank, while the 60Hz I/C is now switched on so that it can charge the batteries and supply power to the 120/240 60Hz distribution panel.

You're covered as long as you choose an inverter that can handle the loads you have. Victron has 3kW and 5kW options as well as the 3.6kW isolation transformer and a 32A auto transformer that fits the bill

[Lowcountry]

I believe that the safest and most simple solution is to approach the situation as if the boat were completely new with NO AC ELECTRICAL COMPONENTS OR WIRING. So, add EVERYTHING NEW required for basic 30amp shorepower service. New inlet, new breaker panel, new inverter/charger, new 8000BTU air conditioner unit, new AC wiring, new AC outlets. That's it. Let's forget about the water heater for now, as that's an unnecessary distraction. I can always run the engine for hot water. What do you think of this approach? Let me reiterate that no components currently on board the vessel would be included in this new system. It would be a completely new, from-scratch PROPER USA-SPEC AC system. Does this sound feasible? Expense is not my top concern. Safety is.