Re: [Amel Yacht Owners] 30 Amp 125 volt shore power to 50 Amp 125/250 Volt plug?

Bill Kinney <greatketch@...>

I am sorry if I confused people. You are of course correct, if a boat was changed, then who knows what it might look like. High voltage wiring is really, really risky to if you do not understand the what’s and whys of what you are doing and the details of all the connections. I should supply more caveats about that.  

I tried to be clear that my comments applied ONLY to a boat with the optional Amel installed transformer wired as Amel originally intended.  The standard configuration Amel built without the transformer (most of them, I believe!) is different and requires different shore power connections.

On boats with an Amel installed transformer as Amel installed it, there is a dedicated 120 volt shore power feed to the transformer which then feeds the 220 volt system on the boat so delivering 120V single phase power to the boat is perfectly acceptable. That is what the transformer is there for!  So 125V single phase power is how I routinely connect to US marinas because it is how my boat was designed by Amel. 

Like you, I have never seen a marina that did not have 50A 125/250 volt service, but I have seen many marinas that did not have 50A-125/250 at every slip. (Like the slip I am in right now…)  So I greatly appreciate the flexibility Amel built into my boat.  

With the transformer, Amel gave me the option of using a 30A-125V or 50A-125V, or 50A-125-250V with one cord, (and suitable inexpensive adapters), OR 220V directly with a separate cord.  For my travels around the US it has been great, because when the marina asks “What kind of power connection do you need?” I can say “Whatever you have!”

Right now I am plugged into a 30 AMP 125 Volt plug and the boat systems are powered with 220 Volt 60 Hz power.  Of course no transformer changes the frequency of the power, so that stays the same as the supply in all cases.

Bill Kinney
SM #160, Harmonie
Annapolis, MD
“Ships and men rot in port."

On Oct 17, 2016, at 12:43, 'Bill & Judy Rouse' yahoogroups@... [amelyachtowners] <amelyachtowners@...> wrote:

Bill Kinney,

If anyone has need to use the Pigtail Shore Power Adapter, 30A 110-125V Male to 50A 125/250V Female, you will deliver 110VAC 60htz to the boat. That is the reason that I said Alex has no need for the plug in the link he sent. 

You said:
"The functional result on the boat is the same as plugging into a 50A-125/250V plug connected with three wires." but what you did not say is that it will only deliver 110-125VAC 60htz to the boat.

Frankly, I do not know what transformer Alex has, what the input requirements are, how it is wired, what its maximum amperage is, and if maybe something has changed since it was installed.

There is a device that will connect to two US type 30A 110-125VAC supplies and deliver 220-250VAC 60htz to the boat. It has 2 each 30A 110-125V Male connectors to connect to the shore power and 1 each  50A 220-250VAC 60htz Female connector to connect to the boat's US style plug. I have one and it will work when each of the 30A 125VAC connections are made to a different 110-125VAC circuit. I used this $800 device once and did not really need it because the marina had both the 30A 110-125VAC 60htz and the 50A 220-250VAC 60htz connections on shore. And, because to use the adapter, the two 30A 125V lines must be connected to a single power source providing from 208V to 250V between them for proper other words, the marina has to have 220-250VAC anyway, but possibly not 30 Amp connections.

My adapter is similar to this one in function:

I also believe that without a complete inspection of Alex's boat, none of can help him accurately.

BeBe 387

On Mon, Oct 17, 2016 at 10:59 AM, Bill Kinney greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


My boat also has the transformer. and having just redone the power cord, I know in detail how MY boat was wired for the 125 volt inlet cord.  This assumes that your existing cord with the 50 Amp connector is wired to bring 125 volts to the transformer.  This is the way my boat is wired. 

It is possible that the 50 A-125/250 volt cord was wired to bring 250 volts directly into the Amel electrical system.  If THAT is true, then the following is NOT true….

That is the correct adapter to make the connection.

USA marinas offer a very confusing number of electrical options. Compounded by the fact that we talk about 110 volts, 115 volts, 120 volts and 125 volts all for the same thing!

The 50 Amp 125/250 volt plug in the USA is a 4 wire plug.  It has a ground, connected to a metal rim, a neutral, and two hots connected to the three pins.  The two hot wires are 180 degrees out of phase, so between the two of them is 250 volts, and from each of those to the neutral wire is 125 volts.

On my boat, there was a 50 A 125/250 V plug on the end of the cord.  ONE of the hot wire pins was connected, along with the neutral and ground to bring 125 volt service on three wires in the boat to the transformer. The other hot wire was not connected.

30 A/125 V service is a 3 wire service.  One hot, one neutral, and one ground.  The adapter will connect the hot wire from the supply to BOTH hot wires in the 50 AMP plug.  Connected like this, each hot wire is 125volts to the neutral, and 0 volts to each other. The functional result on the boat is the same as plugging into a 50A-125/250V plug connected with three wires.

I hope that helps!

Bill Kinney
SM #160, Harmonie
Annapolis, MD
“Ships and men rot in port."

On Oct 17, 2016, at 10:10, Alexandre Uster von Baar uster@... [amelyachtowners] <> wrote:

Good morning, 

The next marina I am going to is likely to only have 30 Amp 125 Volt. 
Since I have never used my big transformer on the boat, I am not sure it works, so trying to cover options.  

I need 220 volt.  
I am very ignorant when it comes to electricity…  

Would the following product be ok?
Or is there a problem with the phases or something else… 

I am not concerned with the Amp, but the voltage…

Thanks in advance!  
Sincerely, Alexandre
Club Nautico de San Juan, Puerto Rico

Join to automatically receive all group messages.