50a to 30a adapter or straight 30a

[Duetto]

hi all,

never really gave this a lot of thought. our boat has a single 30a input that is paralled at the panel. we have a 30a cord.

if the pedestal has both 30a & 50a, am i better to: 1) use a 50-30 adapter, 2) straight 30 3) doesn't matter?

thanks in advance

 

[rslifkin]

When you say paralleled at the panel, what do you mean?

 

[Iggy]

When you say paralleled at the panel, what do you mean?

Wondering that myself?

By plugging in a 30A cord into a 50A socket you will not be protecting that cord. Meaning the breaker will not trip creating a fire hazard. If the cord itself start to short out.

I have seen 30A sockets and wiring burn up just pulling 30A from corrosion in the power station.

Granted the main panel breaker should trip. I would only do that if there was no other socket and for a short time. Not a 24/7 thing

 

[DavidM]

Use the 30a outlet which is protected with a 30a breaker. The 50a outlet has o 50a breaker which is too high for your cord. Admittedly the chances of an overcurrent situation in the cord is slim.

I too don’t understand the parallel statement in the OP.

David

 

[rslifkin]

Wondering that myself?

By plugging in a 30A cord into a 50A socket you will not be protecting that cord. Meaning the breaker will not trip creating a fire. hazard.

Yup, I have that concern every time I see someone using one of those 50A to twin 30A adapters. In my mind, the adapter needs to have breakers in it for that scenario.

 

[Duetto]

there are 2 sub-panels. the ac loads are divided between them. the parallel switch allows both panels to be serviced by the single 30.

there actually are 2 outlets on the boat. if the parallel switch is not in the parallel position then a second cord could feed the second panel and both subpanels would get a full 30a each.

we don't use this because 1) we can run the whole boat off of the one 30 2) we don't have a second cord.

 

[rslifkin]

Do you know if there are main breakers on the boat before the selector switch? If there are breakers to protect the inlets, then it won't matter which way you connect (other than the previously mentioned risk to the cord with a 50A adapter).

But if the main breakers are only on each side of the panel (after the selector switch), then you absolutely should not use the 50A adapter with a single 30A cord. You'd be able to pull more than 30A through the cord without tripping a breaker in that situation, so you'd be at risk of causing an electrical fire.

 

[Duetto]

i THINK the answer is yes. there is a 30A breaker for each sub-panel. i can confirm that when we've accidentally tried to run more than 30A the breaker trips.

also, even with the parallel sw is in the on position, a 30A to the panel 2 will NOT feed panel 1. so practically speaking you need to feed the boat thru panel 1 and then either 1) use the parallel sw to feed panel 2 or 2) use a second 30A cable. panel 2 has a 30A breaker also.

 

[tiltrider1]

If the boat is wired correctly then it doesn’t matter which dock socket you plug into. There will be fewer connections if you use the 30a side so this would give a small advantage.

For the boat to meet ABYC standards there needs to be a 30a circuit breaker after the boat socket and before any switches. This prevents the boat from pulling more than 30a.

30a power cords are really not capable of continuous usage above 25a. If you find yourself continually pulling above 25a then I would look at using two power cords and plugging into the 50a outlet.

 

[Comodave]

If the boat is wired correctly then it doesn’t matter which dock socket you plug into. There will be fewer connections if you use the 30a side so this would give a small advantage.

For the boat to meet ABYC standards there needs to be a 30a circuit breaker after the boat socket and before any switches. This prevents the boat from pulling more than 30a.

30a power cords are really not capable of continuous usage above 25a. If you find yourself continually pulling above 25a then I would look at using two power cords and plugging into the 50a outlet.

+1. I would have a second power cord just for backup. They can go bad. Also check the inlet socket on the boat for burned connectors just for safety every now and then.

 

[ranger58sb]

there are 2 sub-panels. the ac loads are divided between them. the parallel switch allows both panels to be serviced by the single 30.

there actually are 2 outlets on the boat. if the parallel switch is not in the parallel position then a second cord could feed the second panel and both subpanels would get a full 30a each.

we don't use this because 1) we can run the whole boat off of the one 30 2) we don't have a second cord.

FWIW, those would more likely be called inlets (incoming power) versus outlets.

A second cord would likely be an inexpensive spare, usually good to have on board anyway.

That would in turn let you use everything on your primary panel all at once AND fire up the aircon(s) at the time time -- if you're ever in a hot climate. Like Green Cove Springs.

-Chris

 

[Duetto]

i replaced the inlet socket one year ago.

i will be going with the 30A shore power port and the single 30A cord

thanks for all of your comments and suggestions.

 

[Comodave]

i replaced the inlet socket one year ago.

i will be going with the 30A shore power port and the single 30A cord

thanks for all of your comments and suggestions.

Good plan.

 

[DrissZougari]

I have seeing that setup before.
The boat was setup as any dual 30A boat with owner added "parallel switch" Mainly for yard work (to feed other outlets only). the owner knew that he was limited to 30A for both panels combined.
so, i would not recommend using the 50A adapter and the parallel mode at the same.
the issue i can foresee is that you could draw less than 30A on each panel however the combined draw may be much higher to burn the shore panel.
(PS) you can use the adapter without the parallel switch on!!!!!!!

 

[Gdavid]

I have seeing that setup before.
The boat was setup as any dual 30A boat with owner added "parallel switch" Mainly for yard work (to feed other outlets only). the owner knew that he was limited to 30A for both panels combined.
so, i would not recommend using the 50A adapter and the parallel mode at the same.
the issue i can foresee is that you could draw less than 30A on each panel however the combined draw may be much higher to burn the shore panel.
(PS) you can use the adapter without the parallel switch on!!!!!!!

The only 390 I have been on has a pair of breakers at each set of shore power inlets (bow and stern), this should prevent any problem from paralleling the panels on you boat, (assuming it is the same) not sure about the OP's setup.

 

[clburti]

Yup, I have that concern every time I see someone using one of those 50A to twin 30A adapters. In my mind, the adapter needs to have breakers in it for that scenario.

Actually, they do. If one side goes down or is pulled out of the socket, the "special power isolation circuitry for added safety" (Marinco Website) shuts everything down so that cord is not overloaded and the exposed plug is not hot. This is one reason why they are very expensive.

 

[ranger58sb]

Actually, they do. If one side goes down or is pulled out of the socket, the "special power isolation circuitry for added safety" (Marinco Website) shuts everything down so that cord is not overloaded and the exposed plug is not hot. This is one reason why they are very expensive.

I thought that was only in their (#RY504-2-30) "Reverse Y" twin-30A/125V-to-single-50A/250V adapter?

Not in their (#153AY) 50A/250V-to twin 30A/125V adapters?

??

-Chris

 

[clburti]

I thought that was only in their (#RY504-2-30) "Reverse Y" 30A/250V-to-50A/250V adapter?

Not in their (#153AY) 50A/250V-to twin 30A/125V adapters?

??

-Chris

I'm not certain, but I believe that mine is the 125v version and am certain from experience that if one breaker opens or one side comes out, I have no power at the panel.

 

[Bacchus]

I thought that was only in their (#RY504-2-30) "Reverse Y" 30A/250V-to-50A/250V adapter?



Not in their (#153AY) 50A/250V-to twin 30A/125V adapters?



??



-Chris

Above is true.
I have used both the 50A/125V to (2) 30A 125V and 50A/250V/ (2) 30A 125V Y splitters and had abi,it to connect only one 30A cord to power my boat when not needing heat or AC and amp draws were manageable. I made up a blank cover, using one of the threaded rings and a blank gasketed insert, to provide Wx protection when only cord was used.

The 30A reverse Y combiner to provide 50A/250V service is a very different animal and presents significant safety concerns if one of the inputs legs becomes disconnected. That and the need to verify out of phase inputs are used requires a sophisticated safety / monitoring feature be built in. These require both 30A inputs be the correct phase and connected.
Very different adapters... don't get them confused.

 

[Nepidae]

50 to 30 adapter

First, your boat probably has 2 - 30A boat side receptacles, unless you purchased a boat w/o A/C.

1 will be for the house and the other for the A/C.

In my experiences you can't plug a 30A cord into a 50A receptacle or vice versa so I'm not sure where that came from with the breaker issues. Maybe I read that wrong.

Second, it's a good idea to carry a 30 to 50 adapter like this (https://www.defender.com/product.jsp?path=-1|328|2290035|2290037&id=600990). The reason for that is because there are getting to be more & more 50A setups at the marinas.

This would enable you to connect the 2 30A cords that you have to a single 50A receptacle. I often don't bother to hook up the A/C if I'm not going to use it but still use the Y.

IF you are planning on traveling then you might need other adapters as well. I once had to connect to a 15A socket on a dock and needed the adapter to connect my 30A cords to a 15A receptacle.

IF your cords are in bad shape and you think that the boat side receptacles could be updated you might want to consider this (https://www.defender.com/search.html?q=SmartPlug). I think that they find most boat fires are electrical in nature. One of the 1st things I did on our boat where we purchased her in '10 was to upgrade to SmartPlug.

BTW, the only reasons to use 50A is that 1) 50A is all that is available or 2) it is a lesser cost for the 30A.

Hope this helps.

 

[rslifkin]

In my experiences you can't plug a 30A cord into a 50A receptacle or vice versa so I'm not sure where that came from with the breaker issues. Maybe I read that wrong.

Second, it's a good idea to carry a 30 to 50 adapter like this (https://www.defender.com/product.jsp?path=-1|328|2290035|2290037&id=600990). The reason for that is because there are getting to be more & more 50A setups at the marinas.

This would enable you to connect the 2 30A cords that you have to a single 50A receptacle. I often don't bother to hook up the A/C if I'm not going to use it but still use the Y.

That adapter that gives you a pair of 30A plugs from a 50A one is exactly where the breaker issue comes in. If something allows an overload without the boat-side breakers tripping, you could pull 50 amps through a cord designed for 30, as the shore-side breakers won't trip until 50 amps. In other words, the cord between the adapter and the boat (as well as the boat wiring between the receptacle and the first breaker) is not protected when using one of those adapters.

 

[Nepidae]

A good quality Y takes care of the dissimilar voltages, so there are no issues with the boat side breakers. Keep in mind that the pedestals also have breakers.

Having 2 30A on the boat side and using 50A pedestals for 7/8 of the Loop, with our Y adapter, as well as other adapters, I have never had an issue with breakers on either the shore side or boat side.

A lot of factors could be causing your issues, but it being a Y adapter is probably not the case, unless it is homemade unit.

We also have an ELCI in the boat that covers both 30A sockets. That could also have an integral part of our successes.

 

[rslifkin]

A good quality Y takes care of the dissimilar voltages, so there are no issues with the boat side breakers. Keep in mind that the pedestals also have breakers.

Having 2 30A on the boat side and using 50A pedestals for 7/8 of the Loop, with our Y adapter, as well as other adapters, I have never had an issue with breakers on either the shore side or boat side.

A lot of factors could be causing your issues, but it being a Y adapter is probably not the case, unless it is homemade unit.

We also have an ELCI in the boat that covers both 30A sockets. That could also have an integral part of our successes.

It's a situation that's unlikely to have an issue in the real world, but it's a potential one. The boat breakers are 30A, but they're downstream of the cord. Your cords are only good for 30A, but are being protected by a 50A breaker on the shore pedestal when using the adapter. So a dead short will still trip the shore breaker and save you, but a situation that allows an overload (or a partial short) could pull more than 30 amps through the shore cord and burn it up without tripping the shore breakers.

 

[tiltrider1]

First, your boat probably has 2 - 30A boat side receptacles, unless you purchased a boat w/o A/C.

1 will be for the house and the other for the A/C.

In my experiences you can't plug a 30A cord into a 50A receptacle or vice versa so I'm not sure where that came from with the breaker issues. Maybe I read that wrong.

Second, it's a good idea to carry a 30 to 50 adapter like this (https://www.defender.com/product.jsp?path=-1|328|2290035|2290037&id=600990). The reason for that is because there are getting to be more & more 50A setups at the marinas.

This would enable you to connect the 2 30A cords that you have to a single 50A receptacle. I often don't bother to hook up the A/C if I'm not going to use it but still use the Y.

IF you are planning on traveling then you might need other adapters as well. I once had to connect to a 15A socket on a dock and needed the adapter to connect my 30A cords to a 15A receptacle.

IF your cords are in bad shape and you think that the boat side receptacles could be updated you might want to consider this (https://www.defender.com/search.html?q=SmartPlug). I think that they find most boat fires are electrical in nature. One of the 1st things I did on our boat where we purchased her in '10 was to upgrade to SmartPlug.

BTW, the only reasons to use 50A is that 1) 50A is all that is available or 2) it is a lesser cost for the 30A.

Hope this helps.

Here on the west coast you will find your recommended adapter worthless. We have almost no 50a 125v sockets. You will need a 50a 125/250v adapter as the standard pedestal arrangement is one 30a 125v and one 50a 125/250v sockets.

 

[JRO]

You are making a mountain out of a molehill… Think of it as a spoon & ladle. Like a breaker, your mouth size will not allow you to eat your soup with a ladle no matter how hungry you are. If you are popping breakers it’s because you’re trying to use too much power or you are shorting out somewhere. The breakers at the post are known to be old, worn out and in need of replacement. The breakers on your boat should be shipshape. Washing clothes, toasting pop-tarts, microwaving more soup all in the comfortable warmth of two space heaters and taking a shower all at the same time hopefully will pop a breaker somewhere.

 

[Bacchus]

That adapter that gives you a pair of 30A plugs from a 50A one is exactly where the breaker issue comes in. If something allows an overload without the boat-side breakers tripping, you could pull 50 amps through a cord designed for 30, as the shore-side breakers won't trip until 50 amps. In other words, the cord between the adapter and the boat (as well as the boat wiring between the receptacle and the first breaker) is not protected when using one of those adapters.

What you describe IMO is a theoretical but not practical problem.
Can you describe the conditions that will cause an amp draw in the cord that exceeds 30A but does not exceed 50A?
If there is a problem with the cord such as a short of conductors or in the plug how does it exceed 30A but is it limited to <50A??
I've used these Ys for 30 yrs w/o issue and never heard or read of documented issues / hazards. Lots more important, real life issues to worry about than a minuscule theoretical problem.
Just my opinion and we all know what that's worth

 

[rslifkin]

What you describe IMO is a theoretical but not practical problem.
Can you describe the conditions that will cause an amp draw in the cord that exceeds 30A but does not exceed 50A?
If there is a problem with the cord such as a short of conductors or in the plug how does it exceed 30A but is it limited to <50A??
I've used these Ys for 30 yrs w/o issue and never heard or read of documented issues / hazards. Lots more important, real life issues to worry about than a minuscule theoretical problem.
Just my opinion and we all know what that's worth

I agree that it's a pretty unlikely scenario unless one of the boat-side breakers fails and doesn't prevent an overload. But it's still technically wrong and I wouldn't accept it for my own boat.


Thinking about it, there's a second way it can happen. Old boat with 2x 30A inputs and just main breakers on the panel for each leg, but no actual input breakers. You're using the adapter and 1 cord. If the panel transfer switch is configured like my boat and some others of similar age I've seen, you get a selection of "both inlets", "generator", and "inlet 1". Using the inlet 1 position would put you at risk, as you'd be feeding both 30A panel mains from a single 30A inlet with a shore side breaker protecting it at 50A. So if you pulled 20A on each leg, you'd be pulling 40A through the shore cord and could potentially cook it (or the connectors).


In that second scenario, adding inlet breakers on the boat would solve it, but if my understanding is correct, ABYC doesn't require inlet breakers before the panel if the inlet is within a certain distance. And I'm not sure if they say anything about the panel main breakers being source breakers vs panel leg breakers.

 

[JRO]

Electrical mods performed by a backyard hack. A shipshape 30A boat cannot draw more than 30A…. Breakers break the current at 31A if the boat is shipshape.

 

[Duetto]

as the original OP i want to explain how i came to use the 30-50A adapter.

as i described we have a boat basically setup to operate on 30A with the odd time of needing more. we always operated using the single 30 WHEN AVAILABLE. when we started going to the bahamas most of the time it was 50A. initially they gave us a loaner at which time we bought a 30-50 adapter. after 13 years in bahamas it became a habit. we're now using the 30A pedestal with a single cord.

 

[Bacchus]

I agree that it's a pretty unlikely scenario unless one of the boat-side breakers fails and doesn't prevent an overload. But it's still technically wrong and I wouldn't accept it for my own boat.


Thinking about it, there's a second way it can happen. Old boat with 2x 30A inputs and just main breakers on the panel for each leg, but no actual input breakers. You're using the adapter and 1 cord. If the panel transfer switch is configured like my boat and some others of similar age I've seen, you get a selection of "both inlets", "generator", and "inlet 1". Using the inlet 1 position would put you at risk, as you'd be feeding both 30A panel mains from a single 30A inlet with a shore side breaker protecting it at 50A. So if you pulled 20A on each leg, you'd be pulling 40A through the shore cord and could potentially cook it (or the connectors).


In that second scenario, adding inlet breakers on the boat would solve it, but if my understanding is correct, ABYC doesn't require inlet breakers before the panel if the inlet is within a certain distance. And I'm not sure if they say anything about the panel main breakers being source breakers vs panel leg breakers.

If you have a set up that allows a gen and even one cord you have a bigger problem than a Y splitter. I wouldvdoubtnthat was an OEM factory set up?

If you mean either I get it and that's the way mine is set up. I do not believe you can exceed 30A when 1&2 combined... atheist I know on mine it will trip if/ when I exceed 30A. Somehow I doubt that was an "oversight" by ABYC and Mfgrs allowing 60A through one cord/inlet.