50 amp to 30 amp shore power

[rslifkin]

I just don't see any grave danger in a 50A 125/250 cord being split into 2 30's.


The short splitter is the only "under-protected" wire and is aboard where it probably has little or no real threat to it.


Just overworrying in the big scheme of boating threats....unless I read it wrong...they are UL approved so not sure why the distrust.

Typically a boat with twin 30s would use 2x 30 amp cords and put the splitter at the pedestal end, I'd expect. That way they don't need different cords for a marina with only 30 amp outlets. My biggest concern for under-protected wiring in that situation is the inlets on the boat and the run from the inlet to the breaker. Much worse consequences if an issue occurs there, and it's just as under-protected.

 

[Alaskan Sea-Duction]

My boat has a single 50amp male connector. My adapter would connect to my 50 amp male but the two 30 amp ends are female and I need male ends to connect to the power pole. I am connecting to a power pole with two 30 amp female connectors. Your idea is a good one. I have a bunch of cords on board will look into the two 30 amp cord suggestion. Thanks!

Little confusing here.

IMPORTANT: Determine if your boat systems are 120VAC or 240VAC. Most USA boats are 120VAC. But check.

Plugging a 240VAC system into a 120vAC system will SMOKE some systems on your boat! I lost my microwave, TV system because I was stupid. Determine your voltage FIRST!

Sounds like you may need one of these:

https://www.westmarine.com/buy/mari...-to-50a-125-250v-female--10072957?recordNum=1

 

[diver dave]

Typically a boat with twin 30s would use 2x 30 amp cords and put the splitter at the pedestal end, I'd expect. That way they don't need different cords for a marina with only 30 amp outlets. My biggest concern for under-protected wiring in that situation is the inlets on the boat and the run from the inlet to the breaker. Much worse consequences if an issue occurs there, and it's just as under-protected.

You both make valid points. I will say, seeing you and I are both in Rochester area. That home entrance cable (SER) I see all the time up here are fastened to the side of homes without conduit. I was shocked to see that, coming from FL, where it has to be in rigid steel conduit or even 2" of concrete cover. And the houses here are stick houses lined with PVC siding. You have basically unfused #2 AWG conductors running a dozen feet or more over flammable building construction materials connected to the utility transformer from meter pan with no overcurrent protection.
I suppose the risk is low there too...

 

[ranger58sb]

Seevee, if you don't have any 250V loads and your boat is wired as 2 independent 125V / 50A feeds to the 2 halves of the panel (from the 2 phases of the 125/250V inlet), you can use a non-smart adapter to draw from 2x 30A dock outlets without worrying about whether they're on opposite phases or not.

I don't remember ever seeing an adapter like that...

??

-Chris

 

[rslifkin]

The Marinco reverse Y doesn't list that it's a smart unit, although it might be. This (cheap) thing definitely isn't: https://www.amazon.com/Parkworld-Co...+30+to+50+amp+y+adapter&qid=1575405255&sr=8-3

The smart Y adapters are meant to help by making sure you get the pair of 30A plugs on separate phases so you'll get 250V, but if you don't need that, you've got more flexibility. In other words, if you don't have 250V loads, a 50A 125/250V inlet is really just being used as 2x 50A 125V inlets in one plug.

 

[diver dave]

except the shore leads could force 60Amps of neutral current into your 50A rated inlet wire. right?

 

[rslifkin]

except the shore leads could force 60Amps of neutral current into your 50A rated inlet wire. right?

That's a good point if both 30A legs are on one phase. Darn. Still no perfect solution here without a fancy adapter with breakers in it.

 

[tiltrider1]

except the shore leads could force 60Amps of neutral current into your 50A rated inlet wire. right?

This is a real possibility that few people understand when they use twin 30a Y on a 50a 125v/250v system. The saving grace is that over loading the Neutral on the Y is the safest form of overload. Not that overloading is safe.

 

[ranger58sb]

The Marinco reverse Y doesn't list that it's a smart unit, although it might be. This (cheap) thing definitely isn't: https://www.amazon.com/Parkworld-Co...+30+to+50+amp+y+adapter&qid=1575405255&sr=8-3

The smart Y adapters are meant to help by making sure you get the pair of 30A plugs on separate phases so you'll get 250V, but if you don't need that, you've got more flexibility. In other words, if you don't have 250V loads, a 50A 125/250V inlet is really just being used as 2x 50A 125V inlets in one plug.

Hmmm.... thanks. We don't need 250V, so that's why I've been interested.

I once used a single 115V-to-30A adapter, then used a single 30A-to-50A/250V pigtail... and got power to the boat. That was when we were on the hard once, and I just wanted to power our battery charger for a while... and it worked.

But I didn't check whether both legs had power. If so, I guess it would have been about 15A supplying each leg. Not huge, wouldn't run an AC, water heater, cooktop, etc... but would maybe be OK for a short/quiet overnight in a pinch.

except the shore leads could force 60Amps of neutral current into your 50A rated inlet wire. right?

Hmmm... good warning. I was about to do more research on the Marinco reverse Y -- not the Smart Y; we have one of those, successfully used once in approx 15 years -- but a 60A neutral seems to me a showstopper, given I take a cautious approach to most everything to do with electrics.

-Chris

 

[diver dave]

Hmmm.... thanks. We don't need 250V, so that's why I've been interested.



I once used a single 115V-to-30A adapter, then used a single 30A-to-50A/250V pigtail... and got power to the boat. That was when we were on the hard once, and I just wanted to power our battery charger for a while... and it worked.



But I didn't check whether both legs had power. If so, I guess it would have been about 15A supplying each leg. Not huge, wouldn't run an AC, water heater, cooktop, etc... but would maybe be OK for a short/quiet overnight in a pinch.









Hmmm... good warning. I was about to do more research on the Marinco reverse Y -- not the Smart Y; we have one of those, successfully used once in approx 15 years -- but a 60A neutral seems to me a showstopper, given I take a cautious approach to most everything to do with electrics.



-Chris

Expanding the neutral issue a touch. Your panel breaker should include N, So it should trip out when the combined legs exceed 50 A. But, that leaves only a feed of 25A per leg, if they are in phase. So, u really have half of the desired amps avail.

 

[Stabi]

If the marina pedestal has the new 30 milliamp GFCI breakers, will a wye combiner, (2-30 amp male to a 50 amp female) smart or otherwise, work with out tripping?

 

[diver dave]

If the marina pedestal has the new 30 milliamp GFCI breakers, will a wye combiner, (2-30 amp male to a 50 amp female) smart or otherwise, work with out tripping?

Good question. It will depend on where in the feeds the breaker is placed. If the neutral current doesn't equal the line current where the breaker is placed, then it will trip. But, if it is upstream ahead of both 30A recepts, then it will not trip. These devices actually don't know about ground currents, they only respond to N and L unbalance. Some are designed for L1 and L2 vs N also.

I just designed a subpanel for my new dock, and had a choice to put the ELCI at the 60A 240V subpanel feed breaker, or put a 30A single pole 30mA ELCI just ahead of the 120V 30A twist lock. I did the latter.

 

[ranger58sb]

Expanding the neutral issue a touch. Your panel breaker should include N, So it should trip out when the combined legs exceed 50 A. But, that leaves only a feed of 25A per leg, if they are in phase. So, u really have half of the desired amps avail.

Useful to know.

FWIW, in a pinch I'd reckon 25A on each leg could be OK for a brief stop, assuming maybe running minimum stuff, load management, etc.

-Chris