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

Bill Kinney <greatketch@...>


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] <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

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