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Old 07-03-2016, 20:00   #16
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Re: Converting twin 50 Amp 125v to one 50 amp 250?

I'm in a similar problem as the OP.. My boat came with a 50amp 125v connection, so I swapped it out with a 50amp Smartplug with a 50amp 125v connector for the dock side. My boat really doesn't need 50amp as I don't have a A/C on board, biggest load is a water heater. I only have one panel also..

I have thought about cutting the end of the cord and putting a 30amp plug but I really hate cutting factory plugs off. Then I thought about getting an adapter from 50a 125v to 30amp 125v but that's a good deal of money. And with my boat's size, dock connectors are usually 50amp 125/250v receptacles anyways so I would rather get a 50amp adapter

Can I plug into a 50amp 125/250 with an adapter and just use one leg?

I don't mean to side step here from the OP but I literally just finished my electrical rewire and I am using a old cord with a 20amp outlet plug on it as of right now.

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Old 07-03-2016, 20:10   #17
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Re: Converting twin 50 Amp 125v to one 50 amp 250?

As Wayne has stated, you will never see over 50a current on the neutral. If one leg is running 50a, any current on the second leg will actually lower the current on the neutral.

Leg 1 = 50a
Leg 2 = 12a
Single Neutral = 38a
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Old 08-03-2016, 04:45   #18
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Re: Converting twin 50 Amp 125v to one 50 amp 250?

Quote:
Originally Posted by Monepit View Post
One cord has the same capacity but is just one cord. Much easier.
I've seen may use the y. Including my brother, but I would much rather only have to deal with one cord.

Just another minor comment: a single 50/250 shorepower cord is significantly heavy.

When we were shopping on our current boat, I wondered why folks would invest in a Cablemaster (cord reel) since that seemed like such an extravagance. This after only ever having experience with twin 30s, before.

After humping around a 50/250 cable for a while, the value of the Cablemaster began to sink in. We did a retro-fit.

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Old 08-03-2016, 05:24   #19
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Re: Converting twin 50 Amp 125v to one 50 amp 250?

[Yes you can convert 2 X 50A 115V shore power cords into a single one, But..
make sure you are not loading the neutral,
My recommendation is to add an amp meter on the neutral side to better supervise the load, your max load will be 50A (N) compared to your actual setup of 2 X 50A =100A.

We run a 63ft Bertram with enclosed Flybridge, 6 ton chiller and all appliances on a single 50A shore power.
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Old 08-03-2016, 22:03   #20
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Re: Converting twin 50 Amp 125v to one 50 amp 250?

Quote:
Originally Posted by Mabruteam View Post
[Yes you can convert 2 X 50A 115V shore power cords into a single one, But..
make sure you are not loading the neutral,
My recommendation is to add an amp meter on the neutral side to better supervise the load, your max load will be 50A (N) compared to your actual setup of 2 X 50A =100A.

We run a 63ft Bertram with enclosed Flybridge, 6 ton chiller and all appliances on a single 50A shore power.
There is no possibility of more than 50a on the neutral. You do not understand different phases of electricity, they cancel each other. Hence, if each hot leg is running 50a, there will be ZERO amps on the neutral. Yes, you can be consuming 100a total and there will be ZERO amps on the neutral.

No need to monitor the neutral, as it won't tell you anything useful, in fact, it will confuse you as it will show 12a when leg 1 is pulling 36a and leg 2 is pulling 24a (as an example).
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Old 08-03-2016, 22:36   #21
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Re: Converting twin 50 Amp 125v to one 50 amp 250?

just add a new 50a triple pole breaker (required) after the new single shore plug and before the existing panel instead of trying to convert your dual main breakers to a single triple. then just treat your existing main breakers as line 1 and 2 disconnects. join the neutrals feeding each existing main at the output of the triple pole N. (you already have 2 whites here anyways between plugs and panel, one already feading each existing main). now just remove 2nd white wire between new triple main and plugs. mark one of the black hots red instead. grounds should already be joined. but now you only need one 50a galvanic isolator instead of 2. if you have.


this way you don't need to do anything at the panel. and no cosmetic changes to panel. just add new breaker elsewhere. (main breaker should be within 10' of the shore plug anyways, and most panels are not)


if you keep the existing 2 double pole main breakers do not join the Neutral bars after the breakers.
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