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Old 10-05-2019, 08:40 PM   #5
Maerin's Avatar
City: East Coast
Country: USA
Vessel Name: M/V Maerin
Vessel Model: Solo 4303
Join Date: Jun 2013
Posts: 827
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!
Steve Sipe
Selene 4303 Maerin
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