Power from 30a outlet to 50a boat?

[Seevee]

What's the best way to provide 110v 30a source to a 50a boat, to run the 110v stuff? Like the charger. I occasionally run into a situation where 110v 30a is the only choice, like at home where it's docked.

 

[aboatman]

The best way is to buy an adapter from a marine retailer (Marinco, Hubbel, etc.). The second best way is to make one but you have to be sure of what you're doing and it won't be waterproof.

 

[Seevee]

The best way is to buy an adapter from a marine retailer (Marinco, Hubbel, etc.). The second best way is to make one but you have to be sure of what you're doing and it won't be waterproof.

ABoatman,

Thx, do you have a model number, or what it would be called? Would it plug into the shore end of my cord?

Thx

 

[aboatman]

ABoatman,

Thx, do you have a model number, or what it would be called? Would it plug into the shore end of my cord?

Thx

It would plug into the end of your shorepower cord.

I think this is what you want but you would be better off going to the store to make sure:

https://www.westmarine.com/buy/mari...-to-50a-125-250v-female--12998381?recordNum=2

This seems way more expensive than it needs to be so they may have a cheaper adapter in another brand. You're looking for something with a male 30 amp plug and a female 50 amp receptacle. You would plug your 50 amp cord into one end and plug the other end into the 30 amp shorepower pedestal.

 

[ranger58sb]

What's the best way to provide 110v 30a source to a 50a boat, to run the 110v stuff? Like the charger. I occasionally run into a situation where 110v 30a is the only choice, like at home where it's docked.

We can do that with a Marinco 30-to-50 amp pigtail (adapter), similar to what aboatman posted but not the EEL version and I remember ours being WAY WAY WAY less expensive, likely from West Marine.

I've also read that it won't work for 50A/250V boats with a galvanic isolator --
which we don't (yet?) have. In that case, I think a Smart Y and two out-of-phase 30A supplies would be required.

-Chris

 

[psneeld]

Not all 30 to 50s are (were) created equal....unless now they are.

When I was looking for mine a few years back, Furion was the only one I could find that split the dock 30 to both 50 legs on the boat.

Plus Furion was generally cheaper.... and has worked flawlessly the last 3 years being used quite often.

Works fine with a galvanic isolator and not sure why it wouldnt.

 

[Seevee]

It would plug into the end of your shorepower cord.

I think this is what you want but you would be better off going to the store to make sure:

https://www.westmarine.com/buy/mari...-to-50a-125-250v-female--12998381?recordNum=2

This seems way more expensive than it needs to be so they may have a cheaper adapter in another brand. You're looking for something with a male 30 amp plug and a female 50 amp receptacle. You would plug your 50 amp cord into one end and plug the other end into the 30 amp shorepower pedestal.

Thx, I've seen these, expensive and poor reviews. There has to be something out there that works.....

 

[aboatman]

Thx, I've seen these, expensive and poor reviews. There has to be something out there that works.....

But did you read the reviews? Most were sort of stupid.

Go to West Marine and tell them what you need and see what they have. most of the folks at WM are pretty sharp and if they don't know they will ask. And even though WM is often more expensive than mail order, if it doesn't work for you, they will take it back and refund your money. No shipping, no hassle.

A galvanic isolator should make no difference. It's in the ground circuit, not the current carrying conductors.

 

[Seevee]

Good points, will call West, they do have good customer service.

 

[Hal Northstar]

I have a 50 amp service. An adapter, 50 amp female to 30 amp female, plugged into the boat makes it into a 30 amp service. Then a 30 amp shore power cord eliminates the need to muscle around the much heavier 50 amp cord. I have been able to run both a/c units at the same time plugged in to 30 amps.

 

[ranger58sb]

Works fine with a galvanic isolator and not sure why it wouldnt.

I haven't really got a clue about that.

It came up relative to questions about how to charge batteries while on the hard. I allowed as how all I had to do was plug in a single 30-to-50 pigtail, connect that to the boat power, done. (Actually, I was even starting with a household 15A circuit out in the yard's back lot; had to use an adapter from that to 30A first.)

Some of the other owners said that didn't work for them because they had galvanic isolators (starting the year after ours was built). Something about needing two legs for any of their chargers to work at all. Unless maybe they happened to have 240V chargers? Ha. I hadn't thought of that.... Bet that might have been it.

Edit: another "Ha!" It was "isolation transformer" that they mentioned, not a galvanic isolator. If that makes any difference...

-Chris

 

[porman]

We use a 30 amp power cord plugged into a 30 amp shore power outlet and a Marinco adapter between the cord and the 50 amp boat inlet. Everything on the boat works except the reverse cycle heat/AC because it is 250 volt. We use the 30 amp cord because it is easier to handle than the 50 amp cord.

 

[RCook]

Me too. Don't need the 50A setup except to run air conditioning, which doesn't seem to be an issue very often on the Inside Passage.

 

[aboatman]

I haven't really got a clue about that.

It came up relative to questions about how to charge batteries while on the hard. I allowed as how all I had to do was plug in a single 30-to-50 pigtail, connect that to the boat power, done. (Actually, I was even starting with a household 15A circuit out in the yard's back lot; had to use an adapter from that to 30A first.)

Some of the other owners said that didn't work for them because they had galvanic isolators (starting the year after ours was built). Something about needing two legs for any of their chargers to work at all. Unless maybe they happened to have 240V chargers? Ha. I hadn't thought of that.... Bet that might have been it.

Edit: another "Ha!" It was "isolation transformer" that they mentioned, not a galvanic isolator. If that makes any difference...

-Chris

If you have an isolation transformer on your boat (a heavy and expensive device but nice to have) you don't need a galvanic isolator. That could prohibit using a 30 amp to 50 amp adapter.

 

[aboatman]

I have a 50 amp service. An adapter, 50 amp female to 30 amp female, plugged into the boat makes it into a 30 amp service. Then a 30 amp shore power cord eliminates the need to muscle around the much heavier 50 amp cord. I have been able to run both a/c units at the same time plugged in to 30 amps.

If your adapter is female to female, how do you connect the 30 amp cord which is female on the boat end?

 

[Hal Northstar]

I blew it (brain f... ?) ,the adapter is 50 amp female to 30 amp male.

 

[Flatswing]

There are usually 2 types of adaptors:
Smart Y will connect 2 'out of phase' 30A dock receptacles to a single 50A female to plug your 50A cord into-these are expensive ($3-500)but will allow you to run 240v appliances, AC etc ('though you will only get 30A total so need to manage your power draw). You must have 2 active 30A sources one providing L1, the other L2, or the "smart" Y won't work.
Second type is a simple 30A male- 50A female pigtail (typically<$100). it routes the ground to the outer collar for the 50A and connects the hot wire from the 30A to both L1 & L2 legs of the 50A receptacle. This will not power 240v appliances but may run 110v circuits depending on how your boat was wired.

 

[FF]

Most boats with 50-240 have little use for real 240, they just need 2 120V legs.

This requires a jumper to connect both 120v legs to the single 120v leg from a 30a outlet.

This is best done (tho expensive ) with a short purpose built unit., at the power pole using marine components .

IF a 30 A light weight power hose is used the 240 plug will simply have the red and black wires connected.

This works fine ,,,until you forget the vessel is only getting 30A and you turn on too much load.

The 30A plug will loose a terminal in its black wire., or you could melt the 30A wire.

If the boat only needs the ability for a home dock , using RV electrical parts is safe and 1/5 the cost , but not suitable to breaking salt water waves.

 

[ranger58sb]

If you have an isolation transformer on your boat (a heavy and expensive device but nice to have) you don't need a galvanic isolator. That could prohibit using a 30 amp to 50 amp adapter.

Yeah, I don't have either, hence my basic lack of understanding how they work, or symptoms when/if something doesn't work...

And we have no 240V appliances either, so the simple 30-to-50A adapter works fine for light loads.

I've asked the other owners for a memory refresher, so maybe the guys who told me about it in the first place can help me clarify whatever the heck it was I was trying to remember...

-Chris

 

[aboatman]

I blew it (brain f... ?) ,the adapter is 50 amp female to 30 amp male.

Yes, that would work with a 30 amp power cord. The adapter can be on either end of the power cord but if the OP only has a 50 amp cord (because he has a 50 amp boat), he can either buy an adapter for the shore end or buy what you describe and a 30 amp cord.

That said, a 30 amp cord is far less expensive than a 50 amp cord and if he's going to leave it out in the weather for years to come, the 30 amp cord might be the way to go.

 

[aboatman]

For a 50 amp boat at a marina it's possible to buy a "Y adapter that allows the boat to have full power by plugging into two shore receptacles (as long as they are on opposite "legs"). And of course if only one is available or they are both on the same leg you still have 30 amps available.

For the home dock, I would look into the cost of rewiring it for 50 amps.

 

[CaptTom]

IF a 30 A light weight power hose is used the 240 plug will simply have the red and black wires connected.

This works fine ,,,until you forget the vessel is only getting 30A and you turn on too much load.

The 30A plug will loose a terminal in its black wire., or you could melt the 30A wire.

Wait, if the shore power is 30A, then there's a 30A breaker somewhere ashore. Pull more than that and you trip the breaker, not melt the wire.

It's true that the 30A wiring could be degraded and no longer capable of pulling 30A. But the same can be said for a boat wired for only 30A.

My boat is wired for two, 30A circuits (no 240V appliances.) I pretty much permanently have a 30-30-30 "Y" adapter connected, and plug into a 30A outlet wherever I go, including my home dock. I never felt the need to find a 50A outlet (I do have the cords) or even two 30A. A lot of places I've found only 20A or even 15A, and used that without incident.

There is some consideration required concerning load. I think twice before starting the electric range, and check to be sure the air conditioner and/or electric water heater is turned off, first. But it's not rocket science, and the worst I can do is trip a breaker.

 

[ranger58sb]

Yeah, I don't have either, hence my basic lack of understanding how they work, or symptoms when/if something doesn't work...

And we have no 240V appliances either, so the simple 30-to-50A adapter works fine for light loads.

I've asked the other owners for a memory refresher, so maybe the guys who told me about it in the first place can help me clarify whatever the heck it was I was trying to remember...

I got my memory refreshed; that'll maybe last for a nano-second or so...

The guys who told me about it said their system has an isolation transformer (not galvanic isolater as I original mis-said). And their chargers are 110V.

They say unless that transformer has a legit 240V (208+) feed, nothing on the other side of the transformer will work, no matter whether a 220V or a 110V appliance (or charger). They described the transformer acting like a gate... that won't open without typical 50A/250V voltage.

And they said they had to use a Smart Y to get there from here, unlike our easy 30-to-50 adapter solution.

All that transformer stuff is second-hand info; I have no direct experience with this...

-Chris

 

[diver dave]

For a 50 amp boat at a marina it's possible to buy a "Y adapter that allows the boat to have full power by plugging into two shore receptacles (as long as they are on opposite "legs"). And of course if only one is available or they are both on the same leg you still have 30 amps available.

For the home dock, I would look into the cost of rewiring it for 50 amps.

hmmm; are we talking a 50A 120V (3 wire) boat with one inlet connector?
Or, a 50A 4 wire 240/120V boat, or a 2x 50A inlets, or ?

You would be limited to either 30A @ 120V in the first case (with no need for a Y), and 60A @ 120V in the second. The second case doesn't care if in phase or out for the 120V boat loads.

I guess my point is that you can't get a legit 50A from 2 x 30A shore connections thru a single circuit.

AND, a dumb "Y" to parallel two shore outlets into a single circuit is very risky.

 

[diver dave]

They say unless that transformer has a legit 240V (208+) feed, nothing on the other side of the transformer will work, no matter whether a 220V or a 110V appliance (or charger).

-Chris

Many, most? isolation transformers have a dual primary. That is, it can be wired for 240 OR 120V input. But, to change takes a small rewire at the transformer. They are not typically "agile", or smart to do either.

And, don't get me going on 208

 

[ranger58sb]

I don't actually know what an isolation transformer does... or why...

-Chris

 

[diver dave]

I don't actually know what an isolation transformer does... or why...

-Chris

That's a leading statement.

Two main purposes:
First, to "adjust" the voltage as potentially a step up or step down.
Typically, a euro boat would step up a 120V feed to run the ship on 240V.
A US boat in a non-split phase Euro dock would apply the euro 230V 3 wire at the input and get a 230/115V 4 wire at the boat. So, it makes the US to non-US power feed possible, either way.

Second, they block "stray currents". By making the boat ground reference not connected to the dock ground reference. In enginneering speak, an iso transformer blocks common mode currents. Including, lightning induced Line to ground surges.

An iso transformer also gives the capability to provide a non-grounded (aka neutral) output, but this is not typically done for civilian boats. But, military and certain other vessels that benefit from a more reliable power distribution may do this.

ps: I should use "North America" in lieu of "US" above.

 

[ranger58sb]

Second, they block "stray currents". By making the boat ground reference not connected to the dock ground reference. In enginneering speak, an iso transformer blocks common mode currents. Including, lightning induced Line to ground surges.

Thanks. Maybe this is why the maker started adding transformers in later years... at least in the larger range of boats they produced...

I might benefit from adding one, then, given we've had some electronics glitches that I could conceivably ascribe to nearby known/verified lightning strikes.

Nothing catastrophic on our boat, just a few odds and ends... but a couple boats further inside the dock took some serious damage, two different occasions -- and two different set of glitches on our boat afterwards, not immediately recognized (I hadn't known about the second strike until a few months afterwards).

OTOH, back on OP's topic, that'd apparently make it more difficult to use minimal current supplies with simple adapters...

-Chris

 

[FF]

"I might benefit from adding one, then, given we've had some electronics glitches that I could conceivably ascribe to nearby known/verified lightning strikes."

You need a GFI for the vessel, not an isolation transformer that solves the problems of sray current from the dock opr other boats.

 

[ranger58sb]

You need a GFI for the vessel, not an isolation transformer that solves the problems of sray current from the dock opr other boats.

We have several AC outlets with GFCIs... is that what you mean?

-Chris