My boat "leaks" current in new marina… yikes

[macsail]

Most here are probably aware of the 2017 National Electric Code requirements for new marinas to set a threshold for electrical current leakage to 30 mA at the pedestals. Our (new to us) boat trips our new marina in New Orleans. I've had an electrician work for a week to isolate our problem without success. So it's either a new electrician and/or maybe go for the big fix… install an input transformer to provide isolation. The latter solution has other benefits. It eliminates galvanic corrosion to our boat caused by stray currents from neighbors, and assures that we will never be a source of stray current.

As best I can tell, we will need a 15 KVA/120-240V transformer, weighing in at around 170 lbs. Our boat was rewired by the last owner with a single 50 amp/120V input plug (I won't get into it why they did not go with a 240 V system).

Here's my question(s): 1) Am I right to skip the diagnostics and solve with the new transformer? and 2) any suggestions as to make/models of transformers plus any other considerations? I've had a hard time finding "expert" advice.

Our boat is a Marine Trader 50' with three16 kbtu a/c's.

Rick

 

[Swfla]

The Victron brand of galvanic isolation transformer has a lot of different sizes, voltage and amperage setups. It's crucial that you get a perfect match for your setup (which sounds unique from your description). The control panels are quite impressive with the list of options that can be part of the system, battery charging, solar, wind power, inverter, etc. Not just isolating you but maintaining your house batteries and even settings for different types of batteries. Very future friendly. Xantrex is another popular brand.
Having an electrician bond everything and eliminate "leaks" is ideal but as you've found out, is not a quick process. I encourage you to keep at it as well.

 

[Comodave]

Is your electrician a certified marine electrician? That is the first place to start. Current leakage is not an especially difficult problem to solve if the electrician knows what he/she is doing. On the other hand if they don’t know then it can be an unsolvable problem. The electrician should have a plan on how to troubleshoot the problem and then work the plan. With only one shore power inlet the problem is much easier to solve than if there are two inlets. The potential problem of comingled neutrals can’t exist so there is most likely a connection between neutral and ground somewhere on the boat. You start by verifying that the boat can be plugged into the dock without any branch circuits turned on. If that works then progress one by one through the circuits and see which circuit trips the breaker on the dock. Again make sure the electrician is a certified marine electrician not just the guy at the shop that knows something about electrical. Good luck.

 

[ksanders]

I am all for isolation transformers.

As you indicated they isolate your boat from shore power eliminating 100% of the issues.

The only concern I have is that you might have a ground-neutral short in one of your circuits that you should really fix.

 

[boatpoker]

Is your electrician a certified marine electrician? That is the first place to start. Current leakage is not an especially difficult problem to solve if the electrician knows what he/she is doing. On the other hand if they don’t know then it can be an unsolvable problem. The electrician should have a plan on how to troubleshoot the problem and then work the plan. With only one shore power inlet the problem is much easier to solve than if there are two inlets. The potential problem of comingled neutrals can’t exist so there is most likely a connection between neutral and ground somewhere on the boat. You start by verifying that the boat can be plugged into the dock without any branch circuits turned on. If that works then progress one by one through the circuits and see which circuit trips the breaker on the dock. Again make sure the electrician is a certified marine electrician not just the guy at the shop that knows something about electrical. Good luck.

Agree but suggest one step further. An ABYC Certified Corrosion tech has been specifically trained in these issues.

 

[macsail]

Thanks all… great input. Learned (i.e. paid dearly) my lesson about a certified electrician versus the self-proclaimed "expert electrician".

I feel more comfortable now proceeding with the transformer, AND identifying my ground-neutral problem.

 

[tiltrider1]

Yes to isolation transformers.

Solving the current leaking issues is not always as simple as people think. It took us along time to track one issue to some corrosion on the back side of an ac outlet. On another boat we finally tracked the problem down to the heating element in the hot water heater. This was extremely difficult as the issue was random. Often boats have multiple issues that can take awhile to sort out. Finally, if your electrician’s equipment is not sensitive enough, he will never find the problem.

 

[South of Heaven]

I knew Boatpoker would jump on here quick. Deja vu. Lmao. Always a bridesmaid never a bride.

 

[rslifkin]

Do the easy test first. Plug the boat in with every AC breaker off, see if the trip still occurs. Then turn things on one by one and see if you can isolate the problem to a specific circuit. If you've got an idea of where to look for the issue, it'll be much easier to find and fix it.

 

[porman]

Do you have an inverter? Inverter neutrals need to be separate from shore power neutrals.

 

[rslifkin]

Along those lines, if you have 2 power inlets, they need to have separate neutrals.

 

[Swfla]

Here's a link to a current thread about changing inverters. https://www.trawlerforum.com/forums/s4/xantrex-out-victron-53053.html
Hope it's not too much info overload

 

[twistedtree]

I'll reinforce a few things that other have already said.


- Get a different electrician. If he spent a week and came up empty handed, he doesn't know what he's doing, and he's doing it at your expense.


- An isolation transformer is a wonderful thing, but I would solve the problem first, then add the transformer. Don't use the transformer to mask the problem.

 

[Comodave]

Along those lines, if you have 2 power inlets, they need to have separate neutrals.

He said there is only one 50 amp 120 volt inlet.

 

[macsail]

I'm going to take a hard look at my entire electrical system. I have two Raritan converters, and no inverter, so they will only charge my two 12V battery banks off shore power. I definitely want an inverter, don't want to be running the generator all the time for 120V when off of shore power. I expect the last owner was satisfied to have the 12V refrigeration and propane stove, and ran the generator for air conditioning, microwave, and entertainment system. I'll also be looking for more system monitoring.

Porman, I'll be interested to see if the Raritans also need to have separate neutrals from the shore power.

And Swfla, thanks for the timely link on inverters.

I now have the contact info for a qualified electrician.

 

[Comodave]

While you have the electrician onboard I would also check what would be required to upgrade to 50 amp 240 volts. On a 50’ boat I would like to have the extra 50 amps of service available.