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Old 29-03-2021, 15:07   #1
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Step-down Adapter 240v 50a >>> 120v 30a

The dockside power outlet at my slip is 120/240v 50a. I'd like to power a regular 120v 10a sander vacuum off of the dockside power to refinish my bright-work. I know Marinco has an adapter for power going from 120v >>> 240v but not the other way. I guess this is understandable given in theory you'd need some kind of step down breaker to be perfectly safe and not cook the extension cord. However, given my device only draws 10a or so, I'm not too worried. Any "gizmos" out there that might make this work? Btw, this would be male on the dock side, female on the 120v side.



Thanx
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Old 29-03-2021, 16:17   #2
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Here you go

https://www.marinco.com/en/121a
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Old 29-03-2021, 18:16   #3
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Thanks for responding. I guess I didn't explain what I'm looking for very well. I'd like an adapter that will convert 120/240v 50a to 120v 15a (not 30a) so I can use a standard extension cord with a nema 5-15p plug.


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Old 29-03-2021, 18:28   #4
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Actually I think you had part of the solution. Roaming around on Marinco's site I came across this adapter. Looks like adding your adapter to this one should work. Expensive needing to buy 2 adapters though.

https://www.marinco.com/en/199128


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Thanks for responding. I guess I didn't explain what I'm looking for very well. I'd like an adapter that will convert 120/240v 50a to 120v 15a (not 30a) so I can use a standard extension cord with a nema 5-15p plug.
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Old 29-03-2021, 18:35   #5
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Or you could just get the cord end and make your own. Saves a bundle of money
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Old 29-03-2021, 21:59   #6
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Why not just run 15a cord from a boat outlet back onto dock?
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Old 30-03-2021, 09:57   #7
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Re: Step-down Adapter 240v 50a >>> 120v 30a

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Originally Posted by jimp1234 View Post
Thanks for responding. I guess I didn't explain what I'm looking for very well. I'd like an adapter that will convert 120/240v 50a to 120v 15a (not 30a) so I can use a standard extension cord with a nema 5-15p plug.
Jim, it is the draw of what you are using that will determine if you will smoke the extension cord not the availability.
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Old 30-03-2021, 11:22   #8
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Don’t worry about the amperage. A 10 amp sander will only draw 10 amps even if plugged into a 30 or 50 amp service. For example, a 50 amp service is only the max rated amperage.

The 240/120 volts is easy too. There are two hot leads in a 240v service. Each lead is 120v. To get 120v they only use one of these two hot leads.
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Old 30-03-2021, 11:30   #9
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Re: Step-down Adapter 240v 50a >>> 120v 30a

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Jim, it is the draw of what you are using that will determine if you will smoke the extension cord not the availability.
Right. And in my experience, a small extension cord will destroy larger power tools. Always use 12 ga unless it is a very small tool.

As for the adapter:
What you want to do will work. But it will not be completely safe. The 50 amp shore power is protected by a 50 amp breaker. A wire less than about 8 gauge can burn or weld before the 50 amp breaker will trip.

A much better plan is to plug your extension cord into a 120v AC outlet on your boat. That outlet will probably be protected by a 15 or 20 amp breaker or fuse.
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Old 30-03-2021, 17:47   #10
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Home made cords might violate marina regulations and are not safe. "Only manufactured
marine electrical cords and adapters are approved and may be
used in the Marina." See 3.4 in this marina regulation: http://www.rivertownemarina.com/uplo...egulations.pdf
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Old 30-03-2021, 19:49   #11
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Re: Step-down Adapter 240v 50a >>> 120v 30a

Look on the shore pedestal to see if there is also a 110v outlet near the breakers. Our marina's pedestals do and it is very handy for situations like yours. (May be above the breakers.)
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