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Old 14-07-2012, 06:05   #1
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Shore power adapter question

Looking for recommendations on shore power adapters or changes to our cabling. Here's the situation:

Boat has a 50A/125v receptacle.
Dock has 2 - 30A/125 outlets.
Current inventory of cables, connectors and adapters:
- 50A cable with boat end:50A, 125V; dock end: 50A,125/250
- (2) 30A cables with boat end:30A; dock end 30A
- adapter with 30A male to 50A 125/250 female
- 20A cable with boat end 50A, 125V dock end: 15A, 125 (for use with Honda genset)

Problem - only way to get shore power to the boat is to run a single 30A cable from the dock through the adapter to 50A, 125/250 cable to the boat. Works OK but limits available current and have to haul up/down both cables. For the next couple years, we'll be on the Chesapeake, probably at our current marina with the 2 30A receptacles. After that we plan to head for the Bahamas via the ICW. So we'd like to modify our shore power cabling to accommodate both what is prevalent here in the Chesapeake as well as the trip(s) south. And, of course, we're cheap. Money spent on cables comes out of the cruising kitty.

Options - so far I've come up with two options. I would appreciate any other options as well as comments or recommendations about these.

- buy a reverse Y adapter connecting 2 30A dock receptacles to a single 50A, 125/250 cable. Cost about $400 Would allow current 50A cable to be used when we want a lot of power (AC plus water heater, etc) or 1 of the 30A cables when we just run the charger, lights, and small stuff.

- replace the 50A receptacle on the boat with 2 30A receptacles. Would also need to rewire the genset cable with a 30A female end. Cost ??

Unknowns
- what type dockside connections are common in the ICW and Bahamas?
- is there a way to build (safely) a reverse Y adapter for less than $400???
- how hard would it be (and how safe per code) to wire 2 30A receptacles on the boat to a single 50A circuit such that either or both of the receptacles could be in use.
- other things that I don't know I don't know??

Thoughts? Recommendations?

thanks!
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Old 14-07-2012, 07:28   #2
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Re: Shore power adapter question

Quote:
Originally Posted by Paperbird View Post
Boat has a 50A/125v receptacle.
Dock has 2 - 30A/125 outlets.
Current inventory of cables, connectors and adapters:
- 50A cable with boat end:50A, 125V; dock end: 50A,125/250
- (2) 30A cables with boat end:30A; dock end 30A
- adapter with 30A male to 50A 125/250 female
- 20A cable with boat end 50A, 125V dock end: 15A, 125 (for use with Honda genset)
The first Red Flag! is:

The 50A cable with a 125v end and a 125/250v end means that is a diy cable. Are you sure this is the case?

You haven't given any data about what appliances are on the boat.

Assuming the 50A 125v receptacle on the boat is correct, you obviously don't have any 240v appliances, like possibly a big AC. If this is a mistake and you have 240V appliances, you have no choice but to use a 50A 125/250V shore power (and possibly a 30A-50A smart Y adapter). Lacking that, you need to determine how much power the boat requires.

50A 125V will deliver 6250va.
50A 250V will deliver 12500va
30A 125V will deliver 3750va

Determine your current plus future needs and design the system to meet that requirement.

Don't attempt to get more power by connecting (2) 30A outlets to your single 50A 125V receptacle, if the (2) 30A are on opposite phases, you blow breakers. Using (2) 30A cords requires either a 50A 125/250V (and appropriate Y adapter) system all the way to the distribution box, or (2) separate distribution systems.
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Old 14-07-2012, 07:59   #3
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Re: Shore power adapter question

Here's some more background.

The 50A shore power cable is a DIY from the PO. The 125/250 dock end is obviously an add on. Has not seemed to cause any issues, but we only run off a single outlet so haven't had the phase issue you mention.

Major loads are a 16.5 kbtu AC, 1.5kw hot water heater, then the usual misc small loads.

Sounds like I either need to convert the boat wiring to a 50A, 125/250 to the panel with a new receptacle and cable end. Or run a separate distribution system off a second cable for certain loads (maybe just the AC?)
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Old 14-07-2012, 08:11   #4
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Re: Shore power adapter question

Actually your setup is probably not a DIY cable. I had the same setup on my boat and changed the system.

The 50A 125/250V is an old, standard setup that was never common and is pretty much no longer used. At least I have not seen that type of connection at any marina I've stopped at in years. Current standards for dockside power supply, at least in countries like the US that use 60 Hz 125V and 60 HZ 250V systems are either a 30A 125 volt plug or a 50A 250V plug.

You can get expensive adapters but I decided to just change over my whole system. Looking at my energy use I didn't see the need for 50A service so switched to a standard 30A 125V system. Another benefit, the 30A cable is a lot lighter, more flexible so easier to handle and store and a lot cheaper that a 50A cable.

I also decided to go with the new Smartplug system on the boat side. Changing the receptacle on the boat from the old style 50A to a new Smartplug was very easy. Unscrewed the old plug and pulled it out far enough to reach the wiring to the back. Disconnected the old wires and attached them to the Smartplug receptacle. It fit exactly the old holes and even the mounting screws lined up exactly.

Then I purchased a new 30A Smartplug cable with a Smartplug female end to connect to the new receptacle on boat side and a standard 30A 125V plug to go onto the dock end. Very happy with the setup so far and the whole package was not that expensive. Disclaimer, I have no connection with Smartplug, just like it.
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Old 14-07-2012, 08:21   #5
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Re: Shore power adapter question

Quote:
Originally Posted by Paperbird View Post
Here's some more background.

The 50A shore power cable is a DIY from the PO. The 125/250 dock end is obviously an add on. Has not seemed to cause any issues, but we only run off a single outlet so haven't had the phase issue you mention.

Major loads are a 16.5 kbtu AC, 1.5kw hot water heater, then the usual misc small loads.

Sounds like I either need to convert the boat wiring to a 50A, 125/250 to the panel with a new receptacle and cable end. Or run a separate distribution system off a second cable for certain loads (maybe just the AC?)
Further Disclaimer: You know messing around with AC electricity can kill you and cause all sorts of damage to your boat? DO NOT DO THIS YOURSELF UNLESS YOU REALLY, REALLY KNOW WHAT YOU ARE DOING.

Yes. Heed Dotdun's caution about phase matching very carefully.

It sounds like your panel and boat is currently wired for a single phase 125V setup. To fully convert the boat to 50A two phase system would probably require a significant rewiring, possibly a new electric panel. It might be possible to install a small, secondary panel for one or two large loads and feed that panel with one leg of the two phase system but this would require significant knowledge of AC systems or paying someone to do it. This would still require some significant rewiring.

If you can manage your AC use by not running two large loads at the same time, like the AirCon and hot water heater, you can probably get by with the 30A system.
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Old 14-07-2012, 08:38   #6
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Re: Shore power adapter question

The Reverse Y Adapter (167RYN) has two male plugs with special power isolation circuitry for added safety. When one plug is connected to a receptacle, the circuitry isolates the second plug. The reverse Y provides 50A 125/250V power when only 30A 125V receptacles are available.
Note: Reverse Y will NOT work with 50A, 125V, 3-wire inlets. Power is provided in both circuits to the 4-wire inlet, but the dockside receptacles limit the current in each circuit to 30A. The two 30A 125V receptacles must be supplied from a single power source providing from 208V to 250V between them for proper operation.

http://www.marinco.com/files/media/p...nco%20pg27.pdf
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Old 14-07-2012, 09:01   #7
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Re: Shore power adapter question

Hmm. Are the 2 30A receptacles on a power pedestal typically on a single source w/ 250V between them? If so, then would a reverse Y work in our situation?
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Old 14-07-2012, 09:15   #8
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Re: Shore power adapter question

Quote:
Originally Posted by skipmac View Post
Actually your setup is probably not a DIY cable. I had the same setup on my boat and changed the system.

The 50A 125/250V is an old, standard setup that was never common and is pretty much no longer used. At least I have not seen that type of connection at any marina I've stopped at in years. Current standards for dockside power supply, at least in countries like the US that use 60 Hz 125V and 60 HZ 250V systems are either a 30A 125 volt plug or a 50A 250V plug.

You can get expensive adapters but I decided to just change over my whole system. Looking at my energy use I didn't see the need for 50A service so switched to a standard 30A 125V system. Another benefit, the 30A cable is a lot lighter, more flexible so easier to handle and store and a lot cheaper that a 50A cable.

I also decided to go with the new Smartplug system on the boat side. Changing the receptacle on the boat from the old style 50A to a new Smartplug was very easy. Unscrewed the old plug and pulled it out far enough to reach the wiring to the back. Disconnected the old wires and attached them to the Smartplug receptacle. It fit exactly the old holes and even the mounting screws lined up exactly.

Then I purchased a new 30A Smartplug cable with a Smartplug female end to connect to the new receptacle on boat side and a standard 30A 125V plug to go onto the dock end. Very happy with the setup so far and the whole package was not that expensive. Disclaimer, I have no connection with Smartplug, just like it.
Actually, the 50A 125/250V is the standard at marinas that offer 50A. The 50A 125V is the odd one I've never seen at a marina.

If you need more than 30A, which could be the case if you run everything at once, you would need to connect to a 50A source.
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Old 14-07-2012, 09:36   #9
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Re: Shore power adapter question

Quote:
Originally Posted by Paperbird View Post
Hmm. Are the 2 30A receptacles on a power pedestal typically on a single source w/ 250V between them? If so, then would a reverse Y work in our situation?
With your cord, only one of the 125V hot in the 250V plug is connected to your boat, hence you now have a 'single' circuit of 125V to your boat. When connected to a 50A dock service, you'll have 6250VA available. Connecting to dual 30A dock service via a Smart Y adapter (not reverse Y) and assuming the (2) 30A services are on opposite phases (in order for the smart adapter to work), you would only have 30A @ 125V (3750VA) available on your boat due to the diy wiring in your cord and your distribution panel.

You have a couple of choices, the cheapest is to build your own 30A dock service to 50A 125/250V adapter and making sure the correct 125V hot is connected. Then you'll live with 30A 125V max when connected to a single 30A dock service.

A Smart Y adapter will be of no advantage to you unless you make changes to your shore power inlet, cord, and the cabling up to and the distribution box. A Smart Y adapter delivers 30A @ 250V or (2) 30A @ 125V depending on how you utilize it. You can't get a single 60A 125V without a transformer (which wouldn't be a bad idea, just more $$).
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Old 14-07-2012, 11:44   #10
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Re: Shore power adapter question

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Actually, the 50A 125/250V is the standard at marinas that offer 50A. The 50A 125V is the odd one I've never seen at a marina.

If you need more than 30A, which could be the case if you run everything at once, you would need to connect to a 50A source.
Yes, correct. That is what I was trying to say but guess I used the wrong terminology. The 50A plug that is the one on the right in your diagram is the standard in all marinas I've been to in addition to the standard 30A 125V.

The one on the left I am guessing is what the OP has?
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Old 14-07-2012, 11:59   #11
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Re: Shore power adapter question

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Originally Posted by skipmac View Post
Yes, correct. That is what I was trying to say but guess I used the wrong terminology. The 50A plug that is the one on the right in your diagram is the standard in all marinas I've been to in addition to the standard 30A 125V.

The one on the left I am guessing is what the OP has?
The OP has a diy cord, the pic on the left is on the boat end of his cord and the pic on the right is on the dock end of his cord. So, technically he can plug into a 50A 250V service at a marina and have 50A 125V service.
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Old 14-07-2012, 12:11   #12
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Re: Shore power adapter question

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The OP has a diy cord, the pic on the left is on the boat end of his cord and the pic on the right is on the dock end of his cord. So, technically he can plug into a 50A 250V service at a marina and have 50A 125V service.
Do you get 50 amps out of just one leg of a 50A 250V connection?
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Old 14-07-2012, 12:17   #13
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Re: Shore power adapter question

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Do you get 50 amps out of just one leg of a 50A 250V connection?
Yes, each leg will deliver 50A @ 125V independently and/or simultaneously for 6,250VA per leg or 12,500VA of total power.
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Old 14-07-2012, 14:58   #14
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Re: Shore power adapter question

OK, so let me make sure I understand correctly.

With my current set up, I can connect to a 30A 125V shore power receptacle and pull up to 30A (3750va). Or I can connect to a 50A 125/250V shore power receptacle with no adapters and pull up to 50A (6250va).

What I'm not clear on is whether either a smart Y or a reverse Y will allow me to connect my current cable (with a 50A 125/250V dock end) to 2 30A receptacles and pull more than 30A.

As I type this, we are sitting at the dock connected to a single 30A shore power receptacle running the AC and putting a float charge on the batteries. The clamp-on ammeter shows a draw of 13A. I haven't yet tried stressing things by turning on additional loads. It's raining outside and I'm not anxious to pop a dockside breaker and have to mess with it in the rain.
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Old 14-07-2012, 15:41   #15
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Re: Shore power adapter question

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What I'm not clear on is whether either a smart Y or a reverse Y will allow me to connect my current cable (with a 50A 125/250V dock end) to 2 30A receptacles and pull more than 30A.
No, with your configuration, a Smart Y would be a waste money, you'll will not be able to draw more than 30A @ 125V.

A Smart Y delivers (2) 30A 125V to a 50A 125/250V cord making it a 30A 125/250V connection. The reason it's smart is that it won't connect until it see (2) connections out of phase from each other so it can deliver 250v.

Your diy cable is only connected to half the 50A 125/250V circuit, restricting it to 50A 125V. Connecting it to a Smart Y will give you half the 30A 125/250V service (you won't get the 2nd leg), hence 30A 125V. If you are currently connected to a 30A service and it works, that's the best you will do unless you start spending considerable $$.

A reverse Y allows 30A 125V cords to connect to a 50A 125V/250V service.

If it works with the current connection, I wouldn't mess with it.
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