shore power cord question

[magna 6882]

On my boat the boat side is a 50amp smartplug and the other end has a 30amp 120v for the shore side.
I was struggling to figure out how both sides of the panel was being energized with only one leg of power .
What i discovered today is that both L1 and L2 are connected to the one hot leg on the 30amp. This defies my training in electrical but perhaps its normal in the marine industry.
Thoughts?

 

[Comodave]

I have never seen that. Sounds like some PO kludge. I would get a new 50 amp Smartplug power cord. Then if you want to plug into a 30 amp outlet use a proper adapter. Maybe they were trying to get a cheap way to plug the 50 amp boat into a 30 amp receptacle. Where exactly are the 2 legs jumpered together? Inside the cord or inside the boat?

 

[Shifty]

The bridging in the cable was done in the smartplug connector. This is identical to the jump you’d get by using an adaptor like this on the pedestal side. https://www.westmarine.com/buy/mari...0a-125-250v-male-to-30a-125v-female--12998399.

It’s the same circuit, just built into your cable.

 

[magna 6882]

They must be jumped at the 30amp male end. I have been chasing this for three days. I get 120 at both legs on the female end but not a 240 potential. Both grounds are good so the only thing i can surmise is both the red and black are connected to the one hot leg of the 30amp plug. It does charge both sides of the panel and loads are manageable under the current configuration but any additional load would cause the problems with heat at the 30.
I can make it all right but just was not sure if the marine industry was doing something i have never seen.

 

[magna 6882]

The bridging in the cable was done in the smartplug connector. This is identical to the jump you’d get by using an adaptor like this on the pedestal side. https://www.westmarine.com/buy/mari...0a-125-250v-male-to-30a-125v-female--12998399.

It’s the same circuit, just built into your cable.

Hi
The problem is 50amp 120/240 contain two legs out of phase creating a 240 volt potential. If one were to combine the L1 and L2 to one single output that would create a full 240volt short tripping breakers immediately unless i am misunderstanding the 50amp shore connection is two in phase legs.

 

[Comodave]

I would still be leery about it if it did not come from SmartPlug that way.

 

[Shifty]

You’re correct that it’s jumped. This is a 30-amp / 125v cord adapted to feed both sides of your 50 amp / 250 panel (I have the same one). Unless you have AC, you probably don’t have any 240v devices on board. So, you should be getting a total of 30-amps across both 120v sides of your panel.

Without the custom cord, you would need to use a much thicker, heavier 50-amp cord plugged into a chain of adapters - one from smart plug to easy lock and a second from 50 amp to 30 amp. Instead, NP made you a great general-purpose cable, since not all marinas have 50 amp service. But, as you’ve said, you can’t draw more than 30 amps at once. Probably not a risk for most daily use (maybe running the washer, hot water heater, and another big draw device). If you needed more power you could always run your generator.

That said, if your slip at Elliott Bay has 50 amp, you may want to get a normal 50-amp cable so you have full power in your home slip. You could get a shorter one (they’re heavy) that’s just long enough for your home slip.

 

[Comodave]

So NP modified the SmartPlug cables? Interesting.

 

[Shifty]

Hi
The problem is 50amp 120/240 contain two legs out of phase creating a 240 volt potential. If one were to combine the L1 and L2 to one single output that would create a full 240volt short tripping breakers immediately unless i am misunderstanding the 50amp shore connection is two in phase legs.

I don’t think they’re out of phase. Dave walked me through it so you might want to call him. I also found this, which was helpful.

https://www.rvtravel.com/rv-electricity-power-principals-50-amp-shore-power/

“... there’s a center-tap on that 240-volt transformer winding that further divides it into 120/120-volts on each leg. So if you have a 240-volt appliance you connect it between the two hot legs on the outlet. And if you have a 120-volt appliance you connect it between one of the hot legs and the neutral.”

 

[Shifty]

So NP modified the SmartPlug cables? Interesting.

You can buy smart plug ends and make your own cables.

 

[Comodave]

But by modifying them I am pretty sure that any warranty and liability coverage is gone.

 

[magna 6882]

I would still be leery about it if it did not come from SmartPlug that way.

This is a custom cord since it has marinco 30 on one end and a 50amp smartplug on the other. Shifty is right in that is has some convenience but i would rather have an adapter built to go 30 to 50. Also the blue sea components are set up with reverse polarity and power present leds that will only function with 2 poles in addition to the blue seas power protection modules at each input that are also set for 50 amp.

 

[Shifty]

Please let me know if you find an adapter for 30-amp shore to the 50-amp smart plug. I’ve looked and I can’t find a set that doesn’t require two adapters and a 50-amp cord.

 

[psneeld]

Same as the Furion 30 to 50 pigtail adapter. I have been using one for years.

The theory is fine with good power management.....its just how good the jumper was done that you should be interested in.

I am often way more worried about shore power pedestal hook ups in general than my shorepower/panel set up.

 

[twistedtree]

You basically have an adapter built into your power cord. I would get and use a 50A240V straight through cord whenever possible, and set the 30A to 50A aside for use when only 30A shore power is available.


Also, check to be sure all the fault monitoring and RCD breakers work correctly with the adapter cord. If they don't, then I'd ask NP to provide a proper 50A cord to make the boat work correctly.


Does your boat have any 240V devices like HVAC, or perhaps the water heater? Those won't work with the funky cord, and would be further cause to ask NP to supply a cord that allows them to work as designed.

 

[Bacchus]

Magna
Can you clarify if your cord is a 3 wire 30A cord with a 50A Smart Plug attached or a 4 wire 50A cord with a 30A twist lock plug attached.

Also helpful if you can tell us what amp your main breaker or breakers are?

Do you have any other cords or adapters?

 

[tiltrider1]

Is this a 30a 125v cord or a 50a 125v cord or a 50a 125/250v cord?

Does the boat have any 220v appliances or is everything 120v?


It is very possible the PO only needed 30a of 120v so instead of lugging around a 60lbs cord he modified a 20lbs cord for convenience.

There is also the issue of Canada being mostly 208v. A lot of us get around this issue by stepping up the 120v to 240v with transformers on the boat. This way we do not have issues with 208v or finding out of phase 30a plugs.

 

[dhays]

I have no idea how the NP45 is setup. My 2012 NP43 has a 50a/120v service with the standard 50a/120v boat side receptical. It is rare to find 50a/120v service at a dock. Oddly enough that is the type of dock side service I have so I use a 50a/120v power cord at my home dock. When traveling, I use a 30a/120v cord with an adapter.


Smartplug's 50a connectors are designed to be able to be used for either a 120v (3-wire) or 240v (4-wire) application. So the OP's installation is as SmartPlug designed for a boat with a 50a/120v service.

 

[porman]

My boat came with Marinco 50 amp 240 volt boat side recepticals (one at the bow and one at the stern), a Marinco 50 amp cord, and a Marinco 30 amp cord with a Marinco 30 to 50 adapter. The 30 to 50 adapter tied the hot legs, L1 and L2, together. Only the aircon units use 240 volts, so nothing is really lost when on 30 amp power. I changed the boat side to Smartplug 50 amp recepticals. I changed the boat end of the Marinco 50 amp cord to a 50 amp Smartplug. I changed the boat end of the 30 amp Marinco cord to a 50 amp Smartplug and tied the two hot legs together, in effect duplicating what the Marinco adapter did. Now I have one less connection to worry about, the adapter to the cord. I ran this by a marine electrician before doing it and he found no problems. I just don't use the aircon units when on 30 amp power.

 

[magna 6882]

Magna
Can you clarify if your cord is a 3 wire 30A cord with a 50A Smart Plug attached or a 4 wire 50A cord with a 30A twist lock plug attached.

Also helpful if you can tell us what amp your main breaker or breakers are?

Do you have any other cords or adapters?

As far as i can tell its a 4 wire 50 amp smartplug cord with a 30 amp marinco male plug end. Checking voltage at the smartplug end i have 120 volts. The blue sea panel is split with left side being feed with one leg and the other being feed thru the inverter. The auto transfer switch in the inverter then will send shore power to the second panel or with the shore unpluged send power from the inverter. The panels have 50amp main breakers and the inverter feeds are 30. No 240 circuits and only hot water feed from shore

 

[FF]

IF you are going to create your own plugs to send 125V to a leg from a 240v poswer socket , create two.

Many marinas are simply wired so the leg selected to power your boat might be powering 1/2 dozen others.Meanwhile the other 120v leg is doing almost nothing.

This is the usual with purchased plug units , they all select the same 120v leg.

Your heat or air cond may last longer with an extra 20v from the unused leg,! Worth a try

 

[Bacchus]

As far as i can tell its a 4 wire 50 amp smartplug cord with a 30 amp marinco male plug end. Checking voltage at the smartplug end i have 120 volts. The blue sea panel is split with left side being feed with one leg and the other being feed thru the inverter. The auto transfer switch in the inverter then will send shore power to the second panel or with the shore unpluged send power from the inverter. The panels have 50amp main breakers and the inverter feeds are 30. No 240 circuits and only hot water feed from shore

With that info I will venture a guess that the boat was originally wired for 50A 240V with each leg feeding the 50A breakers on each side. I will be a PO dudnt have 50A 240V available and made the change to use a 30A plug instead of using an adapter.
If you have 50A 240V available it shouldn't be a big job to go back to the original configuration and take advantage of the extra power.
Only issue I see with the current set up is the boat mains will not trip when overloading the 30A supply. You are relying on the pedestal for all of your protection. If you continue with the current arrangement I'd consider swapping the main for a 30A breaker.

 

[Comodave]

With that info I will venture a guess that the boat was originally wired for 50A 240V with each leg feeding the 50A breakers on each side. I will be a PO dudnt have 50A 240V available and made the change to use a 30A plug instead of using an adapter.
If you have 50A 240V available it shouldn't be a big job to go back to the original configuration and take advantage of the extra power.
Only issue I see with the current set up is the boat mains will not trip when overloading the 30A supply. You are relying on the pedestal for all of your protection. If you continue with the current arrangement I'd consider swapping the main for a 30A breaker.

+1.

 

[magna 6882]

I made up a new cord last night and will give it a try today.

 

[magna 6882]

I fell ill so only just got out today to check the cord. The new 50amp cord has everything working correctly .It appears some of the led indicators are 240v so are now lighting up. There is so little power draw with this boat the double panel is a little overkill but it works.