How do Y adaptors work and will I get full power to my boat

Before I explain about Y adaptors I want the readers to  be aware that this is just a simplified explanation. Under real conditions at the dock and boat amounts of voltage and amps that can be drawn may fluctuate due to other factors such as tolerances of the circuit breakers.

Let us  start with the 30 amp 125  dock receptacle and a boat with two 30 amp 125 volt inlets

Think of the dock as a pool of amps. A 30 amp 125 volt receptacle on the dock has a 30 amp pool  available. The limit to what can be pulled from the dock is the circuit breaker on the dock.  Normally in a 30amp  125 volt  service it has a 30 amp circuit breaker. Now we do have one more limiting factor.  The boat should have a main circuit breaker panel with a main circuit breaker per inlet . These breakers would matching the inlet  example would be a 30 amp 125 volt inlet will have a 30 amp circuit breaker  limiting the amount of amps the boat can  draw from the dock.  What a Y cord allows you do to is to pull  from this 30 amp pool to your boat.   You can have many combinations of amps drawn all adding up to a total of 30 amps or less.  So 10 amps to one inlet and 20 to the other inlet or 15 to one and 15 to the other  … If the boat tries to draw more than 30 amps from either  inlet  the 30 amp circuit breakers in the boats will trip. If the boat tries to draw more than 30 amps  total between the two inlets  the dock 30 amps circuit breaker will  trip.  Example 25 amps from one inlet and 10 amps from the other inlet  25 amps  + 10 amps = 35 amps.  The 30 amp circuit breaker will trip  at 30 amps.

Next lets look at a  50 amp 125 volt dock receptacle and a boat with two 30 amp 125 volt inlets.

In this scenario the dock now has a pool of 50 amps  with the docks  limiting factor being 50 amp circuit breaker on the dock.  The boat  still has only two 30 amp inlets  with the boats limiting factor being  the 30 amp  circuit breakers in the boat. The Y again will allow you to pull a combination of amps totaling now 50 amps  from the pool; However the circuit breakers  on the boat will only allow you  to pull 30 amps per inlet.  So you can have many combinations of amps  all adding up to 50 amps or less  So you could end up pulling 30 amps to one inlet and 20 to the other or 25 and 25 etc.…… If the boat tries to draw more than 30 amps from either  inlet the  30 amp circuit breakers in the boats will trip. If the boat tries to draw more than 50 amps total  between the two inlets  the dock breaker will  trip.  Example 30 amps to one inlet and 30 to the other inlet.  30 amps  +30 amps  = 60 amps  the  50 amp circuit breaker on the dock will trip at 50 amps .

Another scenario is the  50 amp 125/250 dock receptacle on the dock and a boat with  two 30 amp 125 inlets on the boat.

This scenario is a little different. The  50 amp 125/250 contains two hot wires each containing 50 amp 125 volts.  So in essence two pools of 50 amp. The dock will have a dual circuit breaker  each rated 50 amp 125 volts. Again the boat  still has only two 30 amp 125 inlets  with the boats limiting factor being  the 30 amp circuit  breakers in the boat.   In this case you have two pools of 50 amps . The Y adaptor  will allow each 30 amp inlet to pull from one of the pools. The limiting factor being  the  30 amp circuit breakers on the boat. . So in this case you  can draw 30 amps per inlet or less,  but no more than 30 amps as the 30 amp circuit breakers on the boat will trip.  With the 2 breakers on the dock being rated 50 amps the main limiting factor falls on to the boats breakers.  This set up will allow for the most  power to your boat.


When connecting 2 of the EEL cords or a EEL cord and a old cord togeather I can not get the 30 amp ring over the EEL cordsets male end

The male end of the 30 amp 125 volt  EEL cord set  was made a little thicker than the older style 30 amp cord sets. The 30amp ring currently does not fit over the EEL male end.  The ring that does fit over the EEL male end is the 50 amp ring part number 500R. This ring is big enough to go over the EEL male end of the cord and when using the 110R sealing collar it will tighten up and seal the connection.

The Marinco shore power cord connecting the boat to the pedestal sometimes sags or falls into the water. Does it matter that the cord is in the water?

Although we have never heard of any incident caused by the submersion of a properly maintained shore power cable, the materials and the design are not intended for underwater use. Good electrical practice is to keep the cable out of the water, and stored out of the weather in a dry location when not in use.

We sell clips and hooks that can be used to keep 30 amp shore power cable out of the water. (Part number is CLIP and CLIP-01)

Why is ANCOR recommending using ‘safety’ duplex with Yellow & Red inner conductors?

ANCOR recommends yellow wire as DC negative because black is the standard color for AC hot. There have been many cases of people working on their DC systems who have inadvertently cut the live AC wire. Because of the wide spread use of inverters, power generators and shore power connections, even today’s smallest boats pose a risk of inadvertently cutting into AC wires when working on DC systems.

What is the difference between 50 amps 125 volt and 50 amps 125/250 volt?

The blade configurations are different. In other words, one system may not be used with the other. 50 amps 125 volt is a 3 wire system (1 hot wire, 1 neutral, 1 ground). 50 amps 125/250 volt is a 4 wire system (2 hot wires, 1 neutral, 1 ground). Note: each device has 3 blades. The 4 wire devices are grounded on the side.

Never alter a plug to make it mate with another. If two devices do not fit together, there is an important reason.