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Old 09-07-2016, 10:29 AM   #1
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Dockside Power

Which is the most common 50A dockside power, 50A/120V or 50A/120-240V? I'm planning on changing my 30A to a 50A plug on my boat and I don't want to have something that's uncommon at local marinas. All advice welcomed.
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Old 09-07-2016, 10:41 AM   #2
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"Which is the most common 50A dockside power, 50A/120V or 50A/120-240V?"


Where we are it is 50/120-240 by far.
But the best part of your question is this -"and I don't want to have something that's uncommon at local marinas"


There are places we liked to go that were 50-125 so the question is what are the most common where you boat not where the rest of us are boating.
Having a method/plan to adapt to varied power feeds may also come in handy if you venture out of your normal cruising area.
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Old 09-07-2016, 11:22 AM   #3
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"Which is the most common 50A dockside power, 50A/120V or 50A/120-240V?"

Where we are it is 50/120-240 by far.
But the best part of your question is this -"and I don't want to have something that's uncommon at local marinas"

There are places we liked to go that were 50-125 so the question is what are the most common where you boat not where the rest of us are boating.
Having a method/plan to adapt to varied power feeds may also come in handy if you venture out of your normal cruising area.
What he said.
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Old 09-07-2016, 11:26 AM   #4
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The question is what your boat is wired for and or what the power is at your home dock. You can buy adapters at marine and RV stores. Our boat and dock is wired for 240 volts 50 amps so that is the what the power cord is. We also have an adapter from 240 volts 50 amps to 120 volts 50 amps, and another adapter from 120 volts 50 amps to 120volts 30 amps. The same with the motor home which is wired for 120 30 amps so we have am adapter from 30 amps to 50 amps. What ever you do make sure the boats breaker and wiring can handle it.
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Old 09-07-2016, 11:49 AM   #5
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If your boat is currently wired for 30A 120V then it isn't as simple as replacing the shore power inlet with 50A. If you were to do that then the dockside shore power can supply 50A but your boat's internal wiring is only good for 30A and a fault could start a fire.

I would first make sure that you have a 30A breaker near the shore power inlet (ABYC has required this for some years) and install one if you don't have one. Then replace the shore power inlet with a 50A 120V (why is below) and upgrade the wiring from the shore power inlet to the 30A breaker to #8.

If you are doing this because your AC loads are more than 30A then you have to replace the breaker near the shore power inlet with a 50A one and upgrade all of the wiring to the main panel with #8 wire and upgrade the master breaker on the panel to 50A.

Why a 50A 120V shore power inlet even though almost all marinas have 50A 120/240V power? Well you can't use the 240V or the second leg of 120V and with a couple of adapters you can hook to anything: 30A 120V, 50A 120V or 50A 120/240V at the pedestal.

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Old 09-07-2016, 12:33 PM   #6
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Originally Posted by Dixie Life View Post
I'm planning on changing my 30A to a 50A plug on my boat and I don't want to have something that's uncommon at local marinas. All advice welcomed.
As David outlined very well - you need to address more than the inlet / plug.

What is the problem w/ your existing 30A inlet / plug / cord that you are trying to solve???
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Old 09-07-2016, 01:50 PM   #7
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If your boat is currently wired for 30A 120V then it isn't as simple as replacing the shore power inlet with 50A. If you were to do that then the dockside shore power can supply 50A but your boat's internal wiring is only good for 30A and a fault could start a fire.
That's no different than using a 50 to 30 amp adapter and this is a common practice at marinas where most or all the power pedestals are 50 amp. Yes, it's less than optimal but it's done all the time.

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I would first make sure that you have a 30A breaker near the shore power inlet (ABYC has required this for some years) and install one if you don't have one. Then replace the shore power inlet with a 50A 120V (why is below) and upgrade the wiring from the shore power inlet to the 30A breaker to #8.
The ABYC requirement is to have the appropriate rated circuit breaker (two pole, hot and neutral) within ten feet of the inlet, measured along the length of the wire. If the panel's main breaker meets this requirement, no additional breaker is needed.

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If you are doing this because your AC loads are more than 30A then you have to replace the breaker near the shore power inlet with a 50A one and upgrade all of the wiring to the main panel with #8 wire and upgrade the master breaker on the panel to 50A.
That would leave a potential of 50 amps on a 30 amp panel. Bad plan. You would need to replace the panel with a 50 amp panel.

If your boat's electrical consumption is more than it was designed for, it might be simpler and less expensive and involved to install an additional 30 amp inlet and an additional 30 amp electrical panel. You can probably solve all your problems by connecting just the air conditioner to the new panel.

You will need two 30 amp cords but if you're not going to use the AC you don't need to fool with the second.
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Old 09-07-2016, 02:05 PM   #8
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Wes:

You are willing to use a simple 50A to 30A adapter but you are not willing to upgrade a "30A" panel to 50A by replacing the main breaker??? There is something inconsistent here. Safe is safe, right?.

I do believe that you can safely upgrade the panel. Those internal buss bars are good for hundreds of amps and I will bet that there is absolutely no difference in internal design between a 30A and a 50A panel other than the main breaker.

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Old 09-07-2016, 02:40 PM   #9
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When setting up the system you will need adapters to go all the way from 15A 120v , a house style plug all the way to your onboard maximum.

Out of the way places can have modest power to give away.

I would see no need to upgrade the dual 30A+ 30A inlet breakers because 240v- 50A power can come up the power hose.

The 50A dock breaker will protect the line and inlet , the 30A will still protect the vessel.
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Old 09-08-2016, 06:31 AM   #10
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If your boat's electrical consumption is more than it was designed for, it might be simpler and less expensive and involved to install an additional 30 amp inlet and an additional 30 amp electrical panel. You can probably solve all your problems by connecting just the air conditioner to the new panel.

You will need two 30 amp cords but if you're not going to use the AC you don't need to fool with the second.
+1 on this. You can get a "Y" splitter to go from 50A to two 30A, which gives you more flexibility in hooking up.

I put a breaker for the water heater on both panels, feeding a selector switch so I can power it from either 30A panel. This is one of the better mods I've made.

(The two 30A panels are labelled "Ships" and "Auxiliary", so I used those names on the selector switch.)

A lot of marinas charge more for 50A than 30A. I always ask for 30A, and power both sides with a "Y" adapter. I guess if I HAD to run both air conditioners, plus the water heater and/or electric range at the same time, I'd pay extra for 50A. But so far I've been able to manage my loads and keep the total under 30A.

Some places only offer 20A or 15A. At some of those, the breaker will trip if you try to pull much more than 10A. Then you're really into some load management.
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Old 09-08-2016, 06:59 AM   #11
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50A 125/250 service is very common along the Atlantic ICW.

Then again, so are the 30A power outlets. A simple adapter is what people normally carry.

I went the full route of redoing my AC electrical with upgraded shore power, onboard power panels and new lines/outlets through the whole boat.....never did like the old Taiwanese way of doing it on this boat. 2 AC runs, one port one starboard for all outlets. Nuts.

It was a costly, time consuming project....but as a liveaboard...well worth it.

No one I know would live in a house with only a 50 amp service.....and I sure wasnt again.

I say 50A, because 2 - 30s run below top voltage which is a lot of people's recommendations for safe level of amperage not to burn up 30A plugs (see other shore power thread).

But to change out the plug without changing anything on the boat seems drastic compared to just buying an adapter.
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Old 09-08-2016, 07:11 AM   #12
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Wes:

You are willing to use a simple 50A to 30A adapter but you are not willing to upgrade a "30A" panel to 50A by replacing the main breaker??? There is something inconsistent here. Safe is safe, right?.

I do believe that you can safely upgrade the panel. Those internal buss bars are good for hundreds of amps and I will bet that there is absolutely no difference in internal design between a 30A and a 50A panel other than the main breaker.

David
I wouldn't count on the buss bars being able to handle hundreds of amps. I would get it in writing from the manufacturer or look for a capacity label on the panel itself.

The 50 to 30 amp adapter is only a problem if there is a direct short between the pedestal and the 30 amp main breaker. All but 10' of that risk is outside your boat and it's unlikely there will be damage to the wire inside the boat because it is protected.
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Old 09-08-2016, 07:46 AM   #13
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The 50 Amp 125 service is not seen very frequently. You are better off putting in the 50 Amp /250 service and having an adapter if you do run across 50 Amp 125 service.

This requires a marine electrician to split the service at the panel and if necessary a new panel. When I made the change 18 years ago it only required a new source selector switch, a different breaker and some panel wiring.
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Old 09-08-2016, 09:33 AM   #14
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Some places only offer 20A or 15A. At some of those, the breaker will trip if you try to pull much more than 10A. Then you're really into some load management.


wow,that must be some really old marina.
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Old 09-08-2016, 09:48 AM   #15
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Some places only offer 20A or 15A. At some of those, the breaker will trip if you try to pull much more than 10A. Then you're really into some load management.


wow,that must be some really old marina.
The PO of my boat had a 30 to 20 amp adapter. He said he used it on the Erie Canal.

I used it most recently when we spent a couple nights at a friend's private home and dock. I figured it would be good to power the refrigerator and battery charger. I didn't leave the air conditioner running though, I figured it would trip the breaker in his house and I wouldn't have any power. We stayed in the house.

I've also used it when the boat was hauled and I wanted to use tools on the boat.
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Old 09-08-2016, 09:56 AM   #16
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The PO of my boat had a 30 to 20 amp adapter. He said he used it on the Erie Canal.

I used it most recently when we spent a couple nights at a friend's private home and dock. I figured it would be good to power the refrigerator and battery charger. I didn't leave the air conditioner running though, I figured it would trip the breaker in his house and I wouldn't have any power. We stayed in the house.

I've also used it when the boat was hauled and I wanted to use tools on the boat.
that makes more sense to me as at a friend house,or for tool hookups in a yard.I made up a L5-30p to a quad duplex,just so I could plug in some festoon lighting for a dockside party from the pedestal.
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Old 09-08-2016, 10:13 AM   #17
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Originally Posted by djmarchand View Post
If your boat is currently wired for 30A 120V then it isn't as simple as replacing the shore power inlet with 50A. If you were to do that then the dockside shore power can supply 50A but your boat's internal wiring is only good for 30A and a fault could start a fire.

I would first make sure that you have a 30A breaker near the shore power inlet (ABYC has required this for some years) and install one if you don't have one. Then replace the shore power inlet with a 50A 120V (why is below) and upgrade the wiring from the shore power inlet to the 30A breaker to #8.

If you are doing this because your AC loads are more than 30A then you have to replace the breaker near the shore power inlet with a 50A one and upgrade all of the wiring to the main panel with #8 wire and upgrade the master breaker on the panel to 50A.

Why a 50A 120V shore power inlet even though almost all marinas have 50A 120/240V power? Well you can't use the 240V or the second leg of 120V and with a couple of adapters you can hook to anything: 30A 120V, 50A 120V or 50A 120/240V at the pedestal.

David
Great advice from Dave, as usual. But I would handle the shore plugs a little differently. I would wire my shore cord with a 50A 240V plug, but only wire to one of the two legs. And I would do it simply for convenience. In all my cruising, I have yet to see a 50A 120V dock outlet. No doubt they are out there, but 240V seems way, way more common. With a 50A 240 plug on your shore cord, you can just plug it. Otherwise you will pretty much always have to break out your 50A 240A to 50A 120V adapter. I'd rather use an adapter 5% of the time instead if 95% of the time.

The down side it that your 30A and 120V 50A adapters will be custom, with each powering only one leg of the 240V end. I don't think this poses any safety concerns, but I would carefully label the adapters since they would be specific to your boat.
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Old 09-08-2016, 12:50 PM   #18
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Some places only offer 20A or 15A. At some of those, the breaker will trip if you try to pull much more than 10A. Then you're really into some load management.

wow,that must be some really old marina.
Yup. It's also not uncommon in smaller marinas or fishing ports not used to seeing too many larger (30'+) cruising boats.
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