Shore Power Upgrade - 30 to 50 Amp

[smac999]

Originally Posted by wathey

I'm interested in this thread and had a question and an observation. The observation may not apply directly given it sounds like the live aboard marina may be a semi permanent home for the vessel.
Comment: we have used 20+ marinas this year in Florida, the Bahamas and the us East coast and they all seem to be 120v, either fifty or twin thirty. Which leads to my question.
Question: if you rewire a yacht to use single 50a 240v with two legs of 50a is it compatible with a marina that only has 120v?
Is there a down converter? Also we are parked in super yacht basins all the time that I am sure are this 50/240 configuration but we haven't had an issue with twin 30/120 except for being at the max they can handle both in paper and in actual usage. Did we just not ever dock by a 240 pedestal?
Sorry if I am asking a dumb question here but appreciate the original poster opening this discussion.

this depends on if anyone on the boat is 240v or if everything is 120v. on the OP's boat it sounds like nothing is actually 240v. he's just using 240v plug to get more 120v power. you could still plug the boat into a single 120v outlet and everyting would still work with a single 50a to 30a adapter. but he would be going from 100a of 120v to 30a of 120v and if things were 240v on that boat. you could make 240v using two 120v plugs but they need to be out of phase. and then he would be back to exactly what he has now of 60a of 120v or 30a of 240v

[jamhass]

Ok, I see where I was confused. Our 30A shore power IS 220/240v, so I was assuming your 30A legs were also 220/240v.

[Sailmonkey]

Originally Posted by jamhass

Ok, I see where I was confused. Our 30A shore power IS 220/240v, so I was assuming your 30A legs were also 220/240v.

Where are you finding 30amp 220/240 power?

If it’s rest of the world (outside of North America) shore power is normally 16a or 32a.

[Stasis]

Originally Posted by smac999

you can't just split the 50a 240v inlet to run to 2 seperate double poles at each panel.

Why not? That's essentially what the splitter cord at the dock is doing.

[Palarran]

Stasis, Interesting question. It seems you have some good answers coming in. I just wanted to throw out that I'm not sure how big your boat is and what your running, but: when I bought Palarran I had two 50a 230 shore power connections. 4 years ago I removed one of the shore connections as we had never needed it. This year I changed my shore power cord to a 32 amp European cord and have it on a 30 amp breaker on my boat. I rarely draw more than 25 amps and that's with running a full size clothes dryer. So what is it that draws so much power on your boat? A/C? Battery charger?

[more]

ask the marina captain how many boats share this 50AMP breaker.
In med usually 6-10 boats share 32A on city shore i see 50 boats share 32A breaker normal 230v. ussualy calculation 100 boat 100 kw shore power in good marina. old have 12-20 kw x 3.

[Sailmonkey]

Originally Posted by more

ask the marina captain how many boats share this 50AMP breaker.

In med usually 6-10 boats share 32A on city shore i see 50 boats share 32A breaker normal 230v. ussualy calculation 100 boat 100 kw shore power in good marina. old have 12-20 kw x 3.

What?!?!

I work on several boats, 72’, 76’, 55’….etc…. The average power consumption for those boats at the dock running air conditioning is 12-13kw per boat.

My own little boat on a hot muggy day is close to 1kw.

[more]

Originally Posted by Sailmonkey

What?!?!

I work on several boats, 72’, 76’, 55’….etc…. The average power consumption for those boats at the dock running air conditioning is 12-13kw per boat.

My own little boat on a hot muggy day is close to 1kw.

Dock 72-76 -56 is not some like dock for 25-35 ft or 35-50 ft dock.
in med this big boat must have 63A 3 phase and again couple boats share this 63A 3-phase.

[Stasis]

Originally Posted by Palarran

Stasis, Interesting question. It seems you have some good answers coming in. I just wanted to throw out that I'm not sure how big your boat is and what your running, but: when I bought Palarran I had two 50a 230 shore power connections. 4 years ago I removed one of the shore connections as we had never needed it. This year I changed my shore power cord to a 32 amp European cord and have it on a 30 amp breaker on my boat. I rarely draw more than 25 amps and that's with running a full size clothes dryer. So what is it that draws so much power on your boat? A/C? Battery charger?

Typically when using appliances. Two marine AC units, stove, microwave, washer and dryer, TV, etc. You can get by with limiting what is used at one time. It's in a liveaboard marina, so everything you would use in your home. Many of the other boats in the marina are connected with the single 240/50amp cord.

[Stasis]

Originally Posted by more

ask the marina captain how many boats share this 50AMP breaker.
In med usually 6-10 boats share 32A on city shore i see 50 boats share 32A breaker normal 230v. ussualy calculation 100 boat 100 kw shore power in good marina. old have 12-20 kw x 3.

It's not shared.

[Stasis]

Originally Posted by captstu

If your dock is wired for 249, there are 4 wires with the green, safety ground, normally carries no current.

When a 3 wire 240 volt (red to black) is split down to 2 120 volt circuits, the neutral (white) carries the difference in current of the red and black).

If the same 3 wires, ignore green) ate fed by a splitter with 2 plugs, 30 or 50 amp, the white,neutral, carries the sum of Ref plus Black.

If you feed from 50 amp circuits on the same leg, the may carry up to 100 Amps without tripping a breaker and will melt.
If you. Split at the dock end use a single .50 or twin 30 amp plugs. Do not use twin 50s.

Yes, dock is wired for 240V and I wanted to use a single 240V 50A cord with black and red hots to power two 120V panel sections at 50A. The neutral is what worried me, I wasn't sure if I would bridge the single neutral for both hots.

[captstu]

A single 50 amp split 230 line - as described elsewhere in the thread - is actually safer than dual 30's by a wide margin.

In a single 50, properly wired at the shore power post, the white wire carries the difference in the current of the two hot wires (red - black) and can never exceed 50 amps.

In a 50 amp wire (again, a properly assembled common 50 amp marine cord), the white wire is supposed to carry the difference between the two 30 Amp feeds. If the Marina supplies the two 30 Amp outlets from different "sides" of the main feed, that is what will happen.

If, however, both the 30 Amp outlets are from the same side of the main, the white wire will carry the sum of the two circuits, up to 60 amps, potentially causing overheating that is UNPROTECTED by the two 30 Amp circuit breakers on the Marina power pole.

If you are intending to use the 50 Amp power feed in the long term as a home dock, you should probably measure the voltage in the boat at the circuit breaker (twin 50) you are installing to replace the 30 Amp breakers. That voltage should be a nominal 120 volts from EITHER breaker to the common white - and, crucially, it should be a nomi (nominal 230 volts) between the two circuit breakers.

For the long term, should measure between the white and green wires, Visualize the white wire as the main floor of the house and the red as the bottom floor while the black is the top floor. The white should be in the middle - but to different loads ANYWHERE IN THE MARINA, the white may drift from ground by up to 3 volts and still be within code.

Sometimes, the Marina puts to much load on one side or the other - that is the Marina feed is carrying much more on the Black (or red, they are identical) side so the neutral drifts toward that side. Confusing, but dangerous.

This can happen and may cause a serious shock hazard.

So, make the change, do the measurements and relax - it is the correct and safe thing to do.

[Pau Hana]

Originally Posted by Stasis

Yes, dock is wired for 240V and I wanted to use a single 240V 50A cord with black and red hots to power two 120V panel sections at 50A. The neutral is what worried me, I wasn't sure if I would bridge the single neutral for both hots.

I did this several years ago (changed our 30A x2 to a single 50a split into 2 50A/125v legs feeding 2 panels). I used a Charles Isolation transformer 93-IXFMR12T-A to bring in the 50/250 and split the power into 2 50/125 legs.

With the iso transformer, the neutral from shore never enters the boat.

The actual install:

• Removed the original 30A inlets, and replaced with a single 50/250 inlet https://smartplug.com/product/smartplug-combo-kit/ and inlet breaker https://smartplug.com/product/smartplug-elci-breakers/
• Wired the inlet to the breaker and from the breaker to the inlet of the iso transformer with 6 gauge wire. The neutral does not enter the boat.
• Wired the iso transformer to the vessel panels with 6 gauge, replacing the original 8 gauge 30A wiring.
  

It's been running perfectly for the past 2 years, and we no longer fo the amp dance.

[Stasis]

Just getting back to this... Would this be a good breaker to use?

https://www.bluesea.com/products/312...on_Transformer

[Stasis]

Originally Posted by Pau Hana

I did this several years ago (changed our 30A x2 to a single 50a split into 2 50A/125v legs feeding 2 panels). I used a Charles Isolation transformer 93-IXFMR12T-A to bring in the 50/250 and split the power into 2 50/125 legs.

With the iso transformer, the neutral from shore never enters the boat.

The actual install:

• Removed the original 30A inlets, and replaced with a single 50/250 inlet https://smartplug.com/product/smartplug-combo-kit/ and inlet breaker https://smartplug.com/product/smartplug-elci-breakers/
• Wired the inlet to the breaker and from the breaker to the inlet of the iso transformer with 6 gauge wire. The neutral does not enter the boat.
• Wired the iso transformer to the vessel panels with 6 gauge, replacing the original 8 gauge 30A wiring.
  

It's been running perfectly for the past 2 years, and we no longer fo the amp dance.

Why is a transformer needed? That is a bit more than I want to invest into this.