adequate power at dock
I will be installing A/C on our boat soon and have been advised that we will need a second 30A dock connection. Am I correct in saying that simply using a "Y"-cord will not provide the service we need? I think the purpose of the Y-cord is only for the convenience of supplying two separate 30-amp services when only one of the services is needed at one time?
Thanks.
First thing lets discuss the available power for your pier or slip?
I would check with your marina electrician and see if the marina is set up for 50amp two leg service..... Example my marina has two legs available at each slip...... Some slips have only a single 30amp breaker at their slip and that's because, that's all they need.. While the boat in the next slip over needs and will have a two leg 50amp 125/250 double breaker and appropriate outlet. About two years ago I moved from one slip in the marina to another.
The slip I was in already had a 50amp 125/250 breaker and outlet. The new slip had only a 30amp breaker and outlet. Before I could move they had to check with the electrician to make sure they could add another 50amp service to that pier. That entire dock is already set up with two legs. They just wanted to make sure they were not going to over load the power grid for that pier. Once verified it was okay, all they had to do was change out the 30amp outlet for a 2 leg 50amp 125/250 outlet along a new double pole 50amp breaker.
Now at your marina if they only have single leg service available on your pier, then see if they can change out to a single leg 50amp 125 outlet and single 50amp breaker for your slip. This will alow you to still do a 50amp single leg "Y" with two 30amp pigtail outlets. This will give you the ability to add a second separate 30amp "B" side run on your boat that will be dedicated to just air-conditioners or electric heat. Even if you think your not going to need the second 30amp run because your only adding a small a/c unit , It would be best if you went ahead and did it. This will keeping from always worrying about popping breakers and trying to keep track of electrical loads. If you add the cost of adding a second dedicated 30amp service to your boat with the cost of installing the air conditioner. I think you will find there is not going to be that much extra effort involved. Plus you will be much more satisfied happier in the long run.
NOW....
Check out and study the pictures of my breaker service panel. Your panel does not have to be as elaborate but maybe it can help give you some ideas on what route to take. Notice it has a dedicated 12 volt side...Then it has a dedicated 120volt "A" side and a dedicated 120volt "B" side. Notice in some of the pictures "A" is feeding the "B".... Reason is...I was visiting a marina that only had 30amp service available. So only one 30amp power cord could be used, it was plugged into the "A" side 30amp service inlet at the stern of boat . So I then had only 30amps available. So now I must be very conservative on how many a/c units I can run as well as hot water heater,etc...The next picture is when plugged in to my own slip. I am now using both 30amp cords from boat to dock which is a 2 leg 50amp 125/250 outlet. Notice the separators between the breakers that's for when plugged into and using two 50amp legs this set up is so there is no way for these two separate legs to meet. Can you say 250 volts!

Also notice (look at "A" side) The top breaker is for the shore-power and the bottom is for the generator. Breaker similar on "B" side, top is for shore-power but bottom is for "A" side to feed "B" ..This is when only 30amp service is available at the dock.
Now I hope that was not complicated.
