Reply
 
Thread Tools Search this Thread Display Modes
 
Old 12-19-2019, 12:03 PM   #1
Member
 
City: Jacksonville
Join Date: Dec 2019
Posts: 20
question about shore power

Hi, I have bought an 86 marine trader 42 sundeck. My previous boat has two shore power cables and two ac panels. This one has two shore power cables but only one ac panel. Can someone explain to me how this system works as in two 110 volt inputs to the one panel? I am a bit confused and I do not want to short out my panel.
Thanks John
Malkamus is offline   Reply With Quote
Old 12-19-2019, 12:08 PM   #2
Guru
 
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft 381 Catalina
Join Date: Aug 2019
Posts: 7,554
What are the 2 inputs (30A, 50A, etc.)? Are both inlets next to each other or is it 1 on each side of the boat? And can you post a picture of the panel and any selector switches? It's quite possible the panel is split so part of it gets fed from 1 inlet, the other part from the other inlet. But it's hard to confirm without a bit more info.
rslifkin is offline   Reply With Quote
Old 12-19-2019, 12:28 PM   #3
Guru
 
obthomas's Avatar
 
City: Seabrook Texas
Vessel Name: TheVenture
Vessel Model: 1985 Bestway Labelle Sundeck 40ft
Join Date: May 2013
Posts: 560
I have a 40 foot 1985 marine trader and all the marine traders this size I have seen have two 30 amp 125 volt shore cables. They come into the boat and go to the ship shore switch then to 30 amp breakers that break both the neutral and positive conductors. These conductors are then wired like feeders to two banks of breakers on the same panel. The two banks of breakers are then utilized for the various branch circuit appliances. There is typically an additional switch called a combine switch that will allow one set of breakers to be combined with the other so that all the breakers can be powered from just one of the shore cables if wanted. Of course when in this configuration only 30 amps total is available.

When you have this sort of split phase arrangement on one panel there is a real danger to then try to install and utilize a 220 volt appliance. The safety problem is associated with first separating phases and providing overcurrent protection and the 220 volt appliance can then reconnect the phases setting up a dangerous electrical back feed to a circuit that could be off at its breaker.

I am not an electrician or an expert but I believe what I wrote and I hope it helps. My advice is worth what you paid for it.
obthomas is offline   Reply With Quote
Old 12-19-2019, 01:06 PM   #4
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,786
Obthomas is correct. You probably have two 30A, 120V shore power cables feeding separate busses on the main AC panel. Each buss cannot exceed 30A total (duh!) and there really is no way to obtain 220V but most boats don't need it. And as he notes there is usually a combiner switch that parallels the two busses so they are fed by one breaker, limited to 30A for both busses.

So you can plug your two 30A/120V shore power cords into two 30A/120V pedestal outlets. Another way is to get a 50A/240/120V y-splitter and plug that into the marina's 50A/240/120V outlet and then plug your two 30A/120V cords into the two y-splitter branches. Or if only one 30A/120V outlet is available plug the one in that serves the combiner switch (It will only be one of the two shore power cords. Once you flip the combiner switch the other one will be useless) and flip the switch.

Yours was a common electrical scheme back in the day which has been largely replaced today with a single 50A/240/120V shore power system. Also some marinas only have 50A/240/120V outlets so you probably need to get the y-splitter in case.

BTW, a small nit with obthomas's post. The OP does not have a "split phase" system. He has two 30A systems. They can be powered with split phase sourced power like from a y-splitter or they can both be the same phase, ie not split. The boat's wiring doesn't care which.

David
DavidM is offline   Reply With Quote
Old 12-19-2019, 02:06 PM   #5
Member
 
City: Jacksonville
Join Date: Dec 2019
Posts: 20
Quote:
Originally Posted by djmarchand View Post
Obthomas is correct. You probably have two 30A, 120V shore power cables feeding separate busses on the main AC panel. Each buss cannot exceed 30A total (duh!) and there really is no way to obtain 220V but most boats don't need it. And as he notes there is usually a combiner switch that parallels the two busses so they are fed by one breaker, limited to 30A for both busses.

So you can plug your two 30A/120V shore power cords into two 30A/120V pedestal outlets. Another way is to get a 50A/240/120V y-splitter and plug that into the marina's 50A/240/120V outlet and then plug your two 30A/120V cords into the two y-splitter branches. Or if only one 30A/120V outlet is available plug the one in that serves the combiner switch (It will only be one of the two shore power cords. Once you flip the combiner switch the other one will be useless) and flip the switch.

Yours was a common electrical scheme back in the day which has been largely replaced today with a single 50A/240/120V shore power system. Also some marinas only have 50A/240/120V outlets so you probably need to get the y-splitter in case.

BTW, a small nit with obthomas's post. The OP does not have a "split phase" system. He has two 30A systems. They can be powered with split phase sourced power like from a y-splitter or they can both be the same phase, ie not split. The boat's wiring doesn't care which.

David
So if I understand it is safe to run 2 30 amp cords to the single panel?
Malkamus is offline   Reply With Quote
Old 12-19-2019, 02:08 PM   #6
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,786
Yes
DavidM is offline   Reply With Quote
Old 12-19-2019, 02:12 PM   #7
Member
 
City: Jacksonville
Join Date: Dec 2019
Posts: 20
Quote:
Originally Posted by djmarchand View Post
Yes
thanks a lot i guess that will make it a 50/60 amp service in the end. that answers that question. I am sure I will have many more with this boat it is different from my old Carver.
Malkamus is offline   Reply With Quote
Old 12-19-2019, 02:21 PM   #8
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 2,717
That "combiner" switch is an interesting concept. I haven't run into that, always just used a Y cable. Even at my own home dock, I never bother to run two 30A cables. I just manage the loads so I never exceed 30A total across my two breaker panel sides.

Wouldn't the combiner also have to isolate the grounds when not in the "combined" setting? In other words, a 3-pole switch?

I'm thinking if you had a common ground, you'd risk tripping GFCI breakers on shore.

But maybe I'm missing something...
CaptTom is offline   Reply With Quote
Old 12-19-2019, 02:31 PM   #9
Member
 
City: Jacksonville
Join Date: Dec 2019
Posts: 20
Quote:
Originally Posted by CaptTom View Post
That "combiner" switch is an interesting concept. I haven't run into that, always just used a Y cable. Even at my own home dock, I never bother to run two 30A cables. I just manage the loads so I never exceed 30A total across my two breaker panel sides.

Wouldn't the combiner also have to isolate the grounds when not in the "combined" setting? In other words, a 3-pole switch?

I'm thinking if you had a common ground, you'd risk tripping GFCI breakers on shore.

But maybe I'm missing something...
I will have to run 2 30 amp cables as the marina does not have 50 amp service
Malkamus is offline   Reply With Quote
Old 12-19-2019, 02:41 PM   #10
Guru
 
obthomas's Avatar
 
City: Seabrook Texas
Vessel Name: TheVenture
Vessel Model: 1985 Bestway Labelle Sundeck 40ft
Join Date: May 2013
Posts: 560
Quote:
Originally Posted by CaptTom View Post
That "combiner" switch is an interesting concept. I haven't run into that, always just used a Y cable. Even at my own home dock, I never bother to run two 30A cables. I just manage the loads so I never exceed 30A total across my two breaker panel sides.

Wouldn't the combiner also have to isolate the grounds when not in the "combined" setting? In other words, a 3-pole switch?

I'm thinking if you had a common ground, you'd risk tripping GFCI breakers on shore.

But maybe I'm missing something...
The combiner switch has several poles, and it works. It not only combines all the breakers on one shore cable it shuts off the other 30 amp shore cord.
obthomas is offline   Reply With Quote
Old 12-19-2019, 03:02 PM   #11
Guru
 
diver dave's Avatar
 
City: Palm Coast, FL
Vessel Name: Coquina
Vessel Model: Lagoon 380
Join Date: Jan 2017
Posts: 2,570
Quote:
Originally Posted by obthomas View Post
The combiner switch has several poles, and it works. It not only combines all the breakers on one shore cable it shuts off the other 30 amp shore cord.
I was wondering about that one. Good answer! Keeps a live male plug from happening.
diver dave is offline   Reply With Quote
Old 12-19-2019, 03:48 PM   #12
Guru
 
High Wire's Avatar
 
City: Cape May, NJ
Vessel Name: Irish Lady
Vessel Model: Monk 36
Join Date: Dec 2007
Posts: 4,966
Since we are all guessing on your exact configuration, please consult a qualified ABYC Marine electrician to check your situation and perform mods. There are hundreds of possible deviations of the wiring schemes. You really need a marine electric expert look over the changes you are talking about. Electrical fires, shocks, and knocking out power to your whole dock will ruin your day.

FWIW my boat has 2- 30 amp cords but only one normal breaker panel. No cross ties. The 2nd cord feeds a separate Air Conditioning panel that was added in later by a previous owner.
__________________
Archie
Irish Lady
1984 Monk 36 Hull #46
Currently in Cape May, NJ
High Wire is offline   Reply With Quote
Old 12-19-2019, 04:17 PM   #13
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,786
My 2006 Mainship 34T had exactly the same AC system as the OP describes, with two 30A/120V shore power inlets. The "combiner" discussed above was actually a slide switch on the main panel that locked the main panel breaker for the dead circuit in the off position so it wouldn't back feed it's shore power inlet and make it hot. It also tied the two 120V busses on the main panel together. Very simple and safe.

Since I didn't have air conditioning so my AC loads were well below 30A, I kept the switch in the tie position and always used one cord.

I am always in favor of new boat owners hiring a marine electrician for an hour or so to walk them through everything and explain it. But from what he describes it is the standard two buss, two 30A/120V inlet system and if he doesn't do anything weird like cutting the connectors off of his cord and wiring something different in its place and hooking up to 240V, I don't see how he can go wrong.

David
DavidM is offline   Reply With Quote
Old 12-19-2019, 04:37 PM   #14
Guru
 
fgarriso's Avatar
 
City: .
Vessel Name: GOTCHA
Vessel Model: Hatteras 58 LRC
Join Date: Jun 2019
Posts: 1,103
Take 2 six-packs and call me in the morning.
__________________
Captain F. Lee - R.P.E.
USCG 200 GT Master
fgarriso is offline   Reply With Quote
Old 12-19-2019, 05:29 PM   #15
Moderator Emeritus
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 21,191
One thing to check on your main panel, does it have 2 30 amp main breakers? I have seen quite a few boats of this vintage that have 2 30 amp inlets and only 1 30 amp main breaker. They hot wired the second 30 amp service directly into the bus without any breaker protection. If you don’t have 2 30 amp breakers don’t use both shore power inlets and get a marine electrician to look at it.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Old 12-19-2019, 08:10 PM   #16
Guru
 
CaptTom's Avatar
 
City: Southern Maine
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 2,717
Quote:
Originally Posted by Malkamus View Post
I will have to run 2 30 amp cables as the marina does not have 50 amp service
Oh, sorry, I didn't mention that my Y cable is a 30-30-30. So it's just one cable from a 30A pedestal, and the Y cable is at the power inlets on my boat. I have a couple of 50A adapters, but almost never use them. It's not worth the effort to string a 2nd cable. 30A is all I ever need. I've also been places where all I had was 15A. That really requires some power management.
CaptTom is offline   Reply With Quote
Old 12-20-2019, 02:08 PM   #17
Member
 
City: Jacksonville
Join Date: Dec 2019
Posts: 20
I have a single breaker that is the size of two breakers with one throw lever on it. I say the size of two because it looks like two breakers but it is a one piece breaker not two that are tied together with a throw lever to turn it on and off. I do not have any kind of a lockout for the breaker so I guess if only one shore cable is hooked up the other inlet plug is hot? If it is not raining tonight after work I am going to put a meter on it and see if that is the case.
Malkamus is offline   Reply With Quote
Old 12-20-2019, 02:30 PM   #18
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,786
That single wide breaker is probably a two pole breaker designed for 240V. So I am now confused. I think it is time for a marine electrician to check it out.



David
DavidM is offline   Reply With Quote
Old 12-20-2019, 02:41 PM   #19
Moderator Emeritus
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 21,191
With a single double pole breaker you are breaking the hot and neutral connectors. If there is only 1 30 breaker then your second shore power does not have any over current protection. ABYC recommendations are that there is a over current protection device, circuit breaker, within 10’ along the wires from the inlet. This is a safety issue and each shore power inlet needs to be hooked to a circuit breaker. Unfortunately it appears that there were a lot of boats from that timeframe that were built that way. My President only had one breaker and I know another President that was the same way. I was helping a guy that has a 1987 Carver that has 2 shore powers and only 1 breaker. I replaced my main electrical panel to fix the problem but you can add a 2nd 30 amp double pole breaker to the second shore inlet and it will be much cheaper, if you have physical room to add the second breaker. I also was fixing the problem of my boat tripping the GFCIs on the newly wired docks. All of the neutrals on my boat were on 1 bus bar so the GFCIs on the dock would trip immediately when we plugged in. I split the neutrals into 2 bus bars, 1 for each inlet and fixed that problem. This is a big project and if you are not familiar with MARINE electrical work, then you should get a certified marine electrician to help you do the work.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Old 12-20-2019, 02:44 PM   #20
Moderator Emeritus
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 21,191
Quote:
Originally Posted by DavidM View Post
That single wide breaker is probably a two pole breaker designed for 240V. So I am now confused. I think it is time for a marine electrician to check it out.



David
He said that he has a single breaker that is double wide so that is a 120 volt hot and neutral breaker, he just should have 2 of them.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 02:08 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012