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firstbase 10-05-2019 05:26 PM

Suggested power cables/adaptors
Another shore power cable thread going on so thought I'd throw this up and not derail that one... looking for suggested adaptors for general east caost/Bahamas cruising. We have a 50a 125/250 connetion on the bow and a 30a on the stern. In the slip we are always 50a from dock pedestal to bow to run A/C on board.

Have 2 50' 50a cables and 50' of 30a. What adapters are suggested for cruising? Have thought about changing the 30a stern connection to 50a as the wiring is all there just not in use. Is 30 amp prevelant out and about? Is there a 2 30a to 50a adaptor if I did?

Still electrically challenged..... !

Comodave 10-05-2019 05:47 PM

Personally if it were my boat I would change the 30 amp to a 50. Then no matter which way you dock a 50 foot cord will probably be enough. Then I would get a 2 30 to 50 adapter and a 30 to 50 adapter because some places you may only get one 30 amp outlet. I would go as far as a 15 to 50 if they make them as some places we have found a 15 amp outlet where there really isnít supposed to be any power and we could at least run the battery charger. We carry a long 15 amp extension cord for that.

OldDan1943 10-05-2019 08:00 PM

I am not schooled in marine electrical system. I rely on marine electricians.
IF you attempt to change from 30 amps to 50 amps get the wiring checked and improved by a marine electrician. Of course if you wish, watch, ask questions. SMILE

firstbase 10-05-2019 08:09 PM

Thanks. Yes, electrical work is done by an electrician even the simpler stuff you guys would laugh at paying for. I have electrician on the boat this week and next doing some things for me. replacing a combiner, wiring my bow thruster battery a little differently, adding GFCI's. Changing the stern 30A to 50 is on the list as well but I told him to hold off until I confirmed I wanted that done. Seems like a 30a to 50a adaptor, which I already have as well as a 2 30a Y to 50a, would cover me. Just wondering what conventional wisdom is.

Maerin 10-05-2019 08:40 PM

Change the aft 30A to a 50A. That increases the odds that you'll be able to connect. It sounds like you can't run the A/C with the aft shore power, but you don't say if you have any 230V gear on board. If you don't, you may be able to use a wye combiner to take 2 - 30A sources and convert into a 50A cord connection. It will essentially use the 50A cordset as a dual 30A. Two hot leads and a neutral. You'll only be able to pull 30A, or the limit of the pedestal breaker on each leg of the cord, but unless you have a significant electrical load, you'll be fine. If you have any 230V gear on board, you'll have to have a "smart wye" that senses if the two 30A connections are "out of phase", e.g. they will provide 230V. Sometimes docks aren't wired correctly, and 30A receptacles in close proximity are on the same leg, so you can't get 230V - the smart wye won't connect either line without 230V, so it's dead. That's what makes it smart. In that case, a spare 30A cordset comes in handy to be able to connect to a receptacle that's on the opposite leg and you can get 230V.

My A/C units are all 230V, so this is something we've experienced frequently in our 10 yrs of cruising. One caveat with the smart wye- it's reported that they will trip GFI or ELCI breakers you'll find on recently wired docks that comply with the new electrical code requirements. I've not experienced this, but it's really moot since a marina that's recently upgraded their system will almost certainly have a 50A 230V receptacle.

The other adapter that we use but less frequently is a 30A to 50A adapter. It's made with a jumper that connects the boat's L1 & L2 to the same hot 30A lead, so I can power both legs of the boat's system even though it's not 230V. None of the 230V gear will function, but it's very handy to keep everything else operational with a simple cord connection.

YMMV, perhaps you don't have 230V, that's dependent on the vintage of your electrical system. Some had 50A 125V systems, again, it depends on how your particular system is wired.

As a related matter, if you're planning to cruise and that plan includes marina stays, you're probably going to encounter those GFCI/ELCI equipped marinas mentioned above. You should make sure your boat is ready to connect to one. Nothing more frustrating than arriving at a marina late after a long day cruising and when you connect to the shore power the whole pier goes down. So, before you ship out, have an ABYC electrician check for leakage and commingled neutrals, neutral-ground connections, anything that can trip out the new breakers. It will save a huge amount of headache when you inevitably encounter that 1st marina re-wire!

firstbase 10-05-2019 10:13 PM

Thanks Steve. Nothing 230V onboard. A/C does take 50A. Everything else handled by 30A. I had zinc issues last year, replacing them every month, so had the system reviewed for issues, bonding checked, etc. Found a neutral-ground problem, pinched wire in the stove top and added a galvanic isolator. Also had some leakage in my very old shore power cables so replaced the 50A set. Still have the 30A but have never used it. Looks in much better shape but haven't hooked up a megger to it to check the insulation (hard to believe that I, one of the most severely electrically challenged guys in the world, owns a megger). After all this my whacked out readings went to normal and my zincs went from 1 month to 3-4. An electronics upgrade is in the not too distant future as well as new A/C units. After all is complete I will probably have everything checked out again before we shove off and actually go somewhere of significance.

ksanders 10-05-2019 10:46 PM

As a electrical professional preparing his boat for full time active cruising in areas with dubious facilities, here is what I chose to do.

1. Make your boat dock independent. That means having a generator that can run your boat all the time if necessary.

2. Install isolation transformer(s). This separates yor boats electrical system from the shore side electrical grid, and any problems it might have.

3. Cary adapters to connect to either 30A 120v, or 50A 120V, or 50A 120/208 or 120/240 volt power.

On another note, make your boat water independent as well. Have a watermaker that handles your needs. Know how to work on it, and carry spare parts.

tiltrider1 10-06-2019 02:58 AM

I am just recapping what has already been said.

First know your boat. Some boats have 230v appliances but that does not make them a 230v boat. Is there a step up transformer on one of the 120v legs or does the appliance pull from each leg. We need to know this to determine which type of splitter is necessary.

Secondly, what is your minimum power requirements. Can you get by with 15a, 30a or do you need 50a minimum.

Third, what are the power supply options in your part of the world. In the old days I ran across 15a, 20a, 30a, and 50a/125v. Now I only run into 30a and 50a/125v/250v, which is different from 50a/125v.

Forth, you should either do like Kevin and add an isolation transformer or do like myself and add an ELCI master breaker. This way you will never be the guy who just tripped the whole marina because of leakage.

Finally, I am not familiar with what you will find on the east coat for power options and for those on the west coast, what I carry is over kill but this is what I have on board. “15a to 30a”, “20a to 30”, “30a to 50a/125/250”, “50a/125 to 50a/125/250”. I don’t carry splitters but I don’t have a need for air conditioning and I have a step up transformer for my 230v appliance. Others might want to add a smart splitter to this.

FF 10-06-2019 05:22 AM

If your wiring allows you to power the dock inlet power plugs , they can be used as Buddy Plugs to power a boat rafted to yours.

In some remote areas having a set of 3 or 4 prong 120v and 240v range plugs is needed to have dock power .

These plugs are not marine so much cheaper , and control a bit who gets to plug in.

O C Diver 10-06-2019 05:45 AM


Originally Posted by firstbase (Post 808205)
Have 2 50' 50a cables and 50' of 30a. What adapters are suggested for cruising? Have thought about changing the 30a stern connection to 50a as the wiring is all there just not in use. Is 30 amp prevelant out and about? Is there a 2 30a to 50a adaptor if I did?

Still electrically challenged..... !

Two 30 amp plugs to a single 50 amp 250 volt female plug adapter.

My boat is wired for a 50 amp 250 volt plug. I have no 230 volt appliances, only 120 volt equipment on the boat. When I'm at a marina without a 50 amp 250 volt receptacle, I use the above adapter which limits me to 30 amps on each leg.

This is not a recommendation for you to use it on your boat as I don't know how your boat is wired, this is just what I use on my boat and works for me.


OldDan1943 10-06-2019 06:16 AM

Might be a bit over kill but in my case, I carry 2 extra 30 amp cable and an extra splitter plus the 30 amp adapter and long extension cord to keep the batteries up if I am on the hard.
AND a couple of solar panels on the pilot house roof.

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