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Old 05-01-2010, 16:45   #1
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Changing Boat from Single 30amp to Two 30amp Off 50amp Spliter

What I am doing is changing the boat for one 30 amp panel to Two 30 amp panels feeding off 50amp service.

I have the two 30 amp panels but can not deside what in the boat I should have on each line to even it out the best I can.

What I have been having a problem with is the wife would run the Micro and hair dryer at the same time and blow the breaker, we have now changed to an electrical stove to add to the problem.

What I can not figure out is what to have on line one or on line two.

Here is a list of my electrical needs and a (guess) at the amps/watts they use.

1. Stove 1440 watts

2. Battery Charger 40amp

3. A/C heat right now I have space heaters two of them 1,500 watts each but only run them at 700 watts each, I plan to change this to a 16,000 BUT heat pump this month.

4. Frig. 4.4 cb.ft. power unknown, 45gt. engal A/C D/C frez 2 amp I think on A/C.

5. Hot Water heater power use unknown.

6. Microwave 1,200 watts.

Then if you add things like computer 3amps, T/V 2 amps and so on it really adds up fast.

This month I am making big changes to my use of electric and I know this will help but I still need to figure out the best way to devide what I have listed into two lines.

Please help.


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Old 05-01-2010, 17:23   #2
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Need more info. First of all, are you planning to go to a 50A 220V or a 50A 115V? Makes a lot of difference. Double the wattage to be exact.

The Morgan Out Island is an older boat and the original AC circuits were not all that great. I would suspect that like many boats of that vintage it would not have been wired to the NEC when it was new.

Most of the bigger loads should have a dedicated breaker and anything that pulls much over 10 amps (1200 watts on 115 volts) should be on a 20 amp (#12) circuit. You can run two loads on the same circuit if they will never both be on at the same time (by the NEC), electric heat and air conditioning is a good example.

Trace the wiring and find out what you have. Running 15 amp circuits close to their rated ampacity is a no-no.

Install a rated galvanic isolator in the panel feed line. Your boat will thank you.

One bigger panel with new breakers would be best and then run the older panel as a sub-panel. Does it even have a panel? Many boats don’t. Just worked on a 30 foot Pearson and the original wiring scared me to death! AC must be connected inside of rated panels or boxes. No splices behind the bulkheads!

If this is over your head, hire a professional, a better deal than a smoking shell of a boat if you make a mistake.

Um Saudade

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Old 05-01-2010, 18:03   #3
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First off it is 50amp/220 volt, Yes you are very right that when the boat was new the wiring was a joke but it did have a breaker box (if you want to call it that) when I first got the boat I took all that junk out and ran new wire and put in a Blue Sea 30 amp panel so all the wiring is good now just over grew the 30amp limit when I got married.

You may have seen me talk about her hair dryer in other post due to it is the biggest blame to my electrical problems, she now has a new one because the first went into the river some how.

It is just so hard for me to understand why/how someone would turn every light on in a house/boat start the oven and then go dry your hair, then come to me and say " I just don't know why it all went out" or Have the heat/A/C on but doors/windows open.

I have tried to tell her not only dose it blow a breaker but it could start a fire. But she will do the same time after time.

Ok I'm sorry for venting lol

Like I said above my electrical needs are going to drop alot very soon, I am adding 600watts of solar and 400 watts wind with a house bank of 800AH+ so I plan to charge the batteries off that run the Engal, change the computer system I have now (desktop) to a laptop dump the network, I have to admit the computer/network load I am to blame for. I will also be shaving her head while asleep so this maybe my last post lol.

I have hopes that after all is said and done buy moving loads and removing some toys I can get back below the 30amp as before.

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Old 05-01-2010, 18:10   #4
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The 16k btu when added should be, for best results, on it's own 30A cord. you could add to this the batt charger but not much else, especially not the stove or water heater.
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Old 05-01-2010, 18:12   #5
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Do your research.... last time I priced a 50 amp cord it was over $250...discounted! not to mention the receptacle etc! You see a lot of big boats with two 30 amp for that reason..... and the fact that many marinas dont have 50 amp service anyway....
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Old 05-01-2010, 18:15   #6
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I have hopes that after all is said and done buy moving loads and removing some toys I can get back below the 30amp as before.
You set the max loads on each circuit at the breaker. Should the load get too high the breaker blows. That may not change in your case but so long as you don't over load any one breaker you can be fine. At least with AC you don't have the serious problem of distance and wire size as with DC. Given she may decide to run everything at once it means it's going to blow from time to time even expanded.

Attempting to combine things that won't run at the same time makes sense. Heat and A/C won't both be on at one time so could share. Should the unthinkable happen the breakers blows instantly. In the end you might just be cursed. With twin 30 amp boxes it should be less often. Less often is still better. Could be worse, she could take up welding. Hair dryers in the river are fine so long as not plugged in. Might slow her down at least.
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
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Old 07-01-2010, 19:02   #7
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Well I am very happy to say I have finished the change over to 50amp.

I can not say how much better it is now. I am sitting here coffee pot going both heaters on full and wife in doing her hair. If is was not night time and cold I would go out and do a amp draw now.

With some horse trading my cost was under $100.

I got on Craigslist and found a number of shore power cords and spliters for under $50, one deal was a 50' 30amp cord, 50amp smart spliter and what I call a pigtail (30amp at one end and standert plug other end) I got all 3 for $45. Another deal was 2-50' 30amp cords and a spliter for $50.

I took one 50amp spliter,a xantrax 20amp charger and traded for a panel that was setup with two 30amp mains 6 circuits each. All the other parts I had left over from other odd jobs. I even still have 400' of 30amp cord.

I believe after I sell the Blue Sea Main panel I took out I should come out ahead on my upgrade. The Panel I took out sells at West Marine for $395.

I was sitting here today thinking that before I had a boat I never even really thought about amps/watts in my house I just plugged things in.

well happy sailing all,


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