2x30A shore to 50A on board?

My boat is upgraded to 50A. This includes the isolation transformer, before the switchboard.
Recently, I moved to a different slip in my marina, where there is only 30A pedestals are available. My previous slip had a 50A next to me. Since winter is here, we need to heat our boats, which sucks away the power and appliances are not happy.
I can reach to two different 30A pedestals and I have enough cables to bring them to my boat. The problem is that I cannot find an adapter, which would take the two separate 30A cables and combine them into my 50A 125V on board (male) receptacle.
All my adapters and cables are Marinco, but nobody sells an adapter for my situation.
I need a solution for the 50A/125V male on board, and the 2 x 30A/125V male cables from the pedestals.
I do have adapters, but none of them solve the problem.
- 50A/125V female to 30A/125V male
- 50A/125V female to 50A/125/250V male
- 50A/125/250V male to 2x30A/125V female (pig tale)
I hoped to find a female to female adapter for 50A, but it seems it does not exist. This would allow me to use my male 50A ends on my adapters.
What would you do in this case?

Be very careful. I have a split pedestal with (2) 30 amp sockets and breakers but I'm thinking they are split 230 volts with common neutral.

With 2 pedestals you maybe OK parallel but use a meter and check first.

Here is what you are looking for.
I believe you need to have access to 30A receptacles that are out of phase to get 250V. Not sure about this one but some will not work unless you have the correct phasing.
https://www.boatandrvaccessories.co...yOwbcblk2uLa4JRH6mbZNTu5pgkJGtucaAtpAEALw_wcB
Worth a little more research to make sure you get what you want / need

Delta Riverat said:

With 2 pedestals you maybe OK parallel but use a meter and check first.

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In my case, it would be two individual pedestals, with one breaker/receptacle on each.

Bacchus said:

Worth a little more research to make sure you get what you want / need

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The boat takes 50A/125V only.

Bacchus said:

Worth a little more research to make sure you get what you want / need

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I think I am out of luck. My boat is 50A but only 125V. Even if I had this reverse Y adapter, it will only produce max 30A on one leg.
Plus, I do not even know how the pedestals are phased?

It would be a bit of work but how about moving the heat to its own 30 amp inlet and breaker panel. Then you would have 30 amps left for other things. But be careful about loading a L5-30 connector long term above 24 amps. Or move back to your old slip…

Comodave said:

It would be a bit of work but how about moving the heat to its own 30 amp inlet and breaker panel. Then you would have 30 amps left for other things. But be careful about loading a L5-30 connector long term above 24 amps. Or move back to your old slip…

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No, I am not moving back. Too much rolling at the end of the dock. Lol.
I can survive on the single 30A with careful power management, but the 50A life was more comfortable.
I do have a good diesel heating system. I just do not want to pay the diesel prices for it. What was 60-80 dollars a month heating expense, now it would be easily 300-400 dollars a month, if I run it 24/7.

I am guessing you have a 50 amp cord already to plug into a 50 amp pedestal
You appear to have two 30 amp cords, 50 feet each? Do you have a 50 amp to two 30 amp splitter? Are the two pedestals within 50 feet. If you have not figured out where I am heading then..........
Plug your 30 amp cord in and lead it to the other pedestal where you unplug someone and plug into the 50 footer to free up a 2nd 30amp. But do check to make sure the two are in phase.

I do not think two separate pedestals using separate neutral and grounds from two locations should play well together.

LeoKa said:

No, I am not moving back. Too much rolling at the end of the dock. Lol.
I can survive on the single 30A with careful power management, but the 50A life was more comfortable.
I do have a good diesel heating system. I just do not want to pay the diesel prices for it. What was 60-80 dollars a month heating expense, now it would be easily 300-400 dollars a month, if I run it 24/7.

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Then you probably have some electrical work to do in the boat. It would pay for itself if you do the work yourself. How are you at electrical work?

Comodave said:

Then you probably have some electrical work to do in the boat. It would pay for itself if you do the work yourself. How are you at electrical work?

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Slow. Lol

I can read and learn. I did basic wirings, did my own crimping, breaker upgrades, inverter installs. Of course, I am no professional.
Upgrading the electric panel might be an option, but the rest would be prohibitive to me.

Personally I would convert the boat to 2 30 amp service and get rid of the 50 amp 120 volt all together. Then you will have more flexibility. Here the 50 amp 120 volt is fairly unusual. It would mean a bit of electrical work but…. It isn’t rocket science but rather just a lot of grunt work after you make the plan. And if you do that use SmartPlug inlets and shore power cables.

SteveK said:

I am guessing you have a 50 amp cord already to plug into a 50.

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There is no 50A pedestal near me. Only two 30A individual pedestals with one plug each.
Yes, I have 50A cables and 30A cables. Two of each.
Plus the adapters I have listed already.

I was suggesting one of these to plug into the 50 amp cord

But I see you have single 30 amp pedestals

Comodave said:

Personally I would convert the boat to 2 30 amp service and get rid of the 50 amp 120 volt all together. Then you will have more flexibility. Here the 50 amp 120 volt is fairly unusual. It would mean a bit of electrical work but…. It isn’t rocket science but rather just a lot of grunt work after you make the plan. And if you do that use SmartPlug inlets and shore power cables.

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You are making a good point. My only problem with the conversion is the isolation transformer, which is 50A and everything is wired accordingly.
Perhaps, two 50A circuits upgrade instead?
What if there are two panels, each handling a set of breakers for the section of the boat. The main breaker on each panel can be 50A, so my transformer does not need to be changed.
I am not sure how much more expensive it would be? I can afford the wiring, 50A breakers, receptacles. The circuit boards are pricey, unless I am able to utilize the existing sub panels.

It doesn't sound like you're going to get more than 30 amps into your shore power.

I've done as Commodave suggested and built a second 30a stand-alone service to run portable electric heat and/or bubblers in the winter. Works for me.

I am not sure if the 50 amp isolation transformer can be used on a 30 amp circuit. I would check with the manufacturer and see.

Comodave said:

Personally I would convert the boat to 2 30 amp And if you do that use SmartPlug inlets and shore power cables.

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Take a look at this one. It handles two shore power connections, even at 50A. The price is around $600. From this one, the rest of the existing panels can be branched out.

https://www.go2marine.com/Paneltron...lel-Switch-w-Meters-5306?quantity=1&type=1240


I am just thinking out loud here. If this can take two 50A connections, all I need is two 50A receptacles and wiring. The description says that it can handle two individual hot and neutral bars. I suppose this will allow me to connect to either 30A or 50A pedestals. Unless I misunderstand the description.

There is no good answer because of your isolation transformer. Ideally I would recommend converting to 50a 125/250. This would require a new isolation transformer, lots of panel work and lots of wiring.

You could leave your 50a 125v alone and just use an adapter to plug into a single 30a. You could then set up a separate 30a panel that only runs a few heaters. This is probably the simplest and cheapest way to solve your problem. This second panel could be hidden in a closet as it would most likely consist of a main breaker and two secondary breakers.

LeoKa said:

There is no 50A pedestal near me. Only two 30A individual pedestals with one plug each.
Yes, I have 50A cables and 30A cables. Two of each.
Plus the adapters I have listed already.

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Ask the marina to change your pedestal?

Could be simple. Might not even charge you, but if they do, might not be much.

-Chris

LeoKa said:

Take a look at this one. It handles two shore power connections, even at 50A. The price is around $600. From this one, the rest of the existing panels can be branched out.

https://www.go2marine.com/Paneltron...lel-Switch-w-Meters-5306?quantity=1&type=1240


I am just thinking out loud here. If this can take two 50A connections, all I need is two 50A receptacles and wiring. The description says that it can handle two individual hot and neutral bars. I suppose this will allow me to connect to either 30A or 50A pedestals. Unless I misunderstand the description.

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That panel lets you select between two shore cords and a generator, but you can only use one at a time. There is no provision to combine anything.


You only have two choices:


1) Live with 30A/120V


2) Split up you power system into a 50A,120/240V split phase system. Then you can run off a 50A 120/240V shore outlet, or use a combiner to run off of two 30A 120V shore outlets. But if you have a generator you will need to consider how that fits, along with the isolation transformer. It's a big project.

ranger58sb said:

Ask the marina to change your pedestal?

Could be simple. Might not even charge you, but if they do, might not be much.

-Chris

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Yep! You would be using one socket rather than two.

SteveK said:

I was suggesting one of these to plug into the 50 amp cord

But I see you have single 30 amp pedestals

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These are incredibly dangerous, and illegal to use in any jurisdiction that required NEC compliance, which is pretty much everywhere.


The only safe way to combine two 30A power sources into a 120/240 power source is with some form of intelligent switch. That's why the Marinco or Furrion version of these combiners cost $600 or more. They only connect power through to the 120/240V side if both 30A supplies are present, and only if they are out pf phase.


A hard wired adapter like the one in this listing are dangerous in two ways:


1) If the two 30A power sources are in phase, then you can overload the neutral. When the power sources are out of phase, as they should be, the neutral current is the difference between the two phases. When they are in phase, the neutral current is the SUM of the two phases, so can run at 60A without any breakers tripping. That's a good way to start a fire.


2) If you plug in one of the 30A ends, and there are 240V loads connected on the boat side, the exposed plug prongs of the second 30A end will be live/hot. That's a good way to get electrocuted.


Oh, and it wouldn't help the OP anyway because his boat takes 50A 120V, not 120/240V.

twistedtree said:

These are incredibly dangerous, and illegal to use in any jurisdiction that required NEC compliance, which is pretty much everywhere.


The only safe way to combine two 30A power sources into a 120/240 power source is with some form of intelligent switch. That's why the Marinco or Furrion version of these combiners cost $600 or more. They only connect power through to the 120/240V side if both 30A supplies are present, and only if they are out pf phase.


A hard wired adapter like the one in this listing are dangerous in two ways:


1) If the two 30A power sources are in phase, then you can overload the neutral. When the power sources are out of phase, as they should be, the neutral current is the difference between the two phases. When they are in phase, the neutral current is the SUM of the two phases, so can run at 60A without any breakers tripping. That's a good way to start a fire.


2) If you plug in one of the 30A ends, and there are 240V loads connected on the boat side, the exposed plug prongs of the second 30A end will be live/hot. That's a good way to get electrocuted.


Oh, and it wouldn't help the OP anyway because his boat takes 50A 120V, not 120/240V.

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If "When the power sources are out of phase" than you would have 203V? Yes?

Iggy said:

If "When the power sources are out of phase" than you would have 203V? Yes?

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In this context, out of phase would give you 240V across L1 and L2. In phase would give you 0V across L1 and L2. Is that what you are asking, or are you asking about 240V vs 208V?

Leoka
Now I understand your situation and what is desired.
You would need to check the 30A receptacles but if same phasing one of these should do what you want.
https://www.amazon.com/Adapter-30A-125V-50A/dp/B0013HRJVM

twistedtree said:

In this context, out of phase would give you 240V across L1 and L2. In phase would give you 0V across L1 and L2. Is that what you are asking, or are you asking about 240V vs 208V?

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It my club the have 3 phase. I was thinking that if you came off the 2 hot wire you would 208. But one one hot to natural you would have 120V due to there out of phase. I think by 45 degrees. OK, over thinking it.

Was just going to say the same thing as Ranger... Just convert the 30a pedestal to 50a and not have to worry about plugs/adapters/cables... Shouldn't be more than $500 to change you out...

Bacchus said:

Leoka
Now I understand your situation and what is desired.
You would need to check the 30A receptacles but if same phasing one of these should do what you want.
https://www.amazon.com/Adapter-30A-125V-50A/dp/B0013HRJVM

Click to expand...

That appears to be a splitter, taking a 50A 120V shore outlet and splitting it into two 30A 120V sources. He wants to do the reverse, and you can't do it without violating countless wiring and safety codes

Scottwb96 said:

Was just going to say the same thing as Ranger... Just convert the 30a pedestal to 50a and not have to worry about plugs/adapters/cables... Shouldn't be more than $500 to change you out...

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Good idea if the marina will allow it.