Category Archives: Boat Wiring

Floating Green?


I have just purchased a 7KVA generator set to replace my old one on my marine electrical system. The unit is supplied connected M.E.N. internally with output supply connected to a bipole circuit breaker.

As the connections between earth and neutral is before the the breakers, there is no allowance for the earth wire from the appliance side to connect to on the genset. Should I wire this appliance earth onto the frame of the genset or leave it ‘floating’?Westerbeke Generator


Hi A.T.,

The green, earth wire from your AC system needs to be connected to the chassis of the new generator. It should not be floating. With AC systems, the neutral and ground are connected at the source of power (the generator). The neutral and ground remain separate on the rest of the boat. The neutral is connected through the breaker and the ground directly.

The reality is, once the generator battery ground is connected to the rest of the battery negatives on the boat, the green, earth wire path is complete. Your AC system green earth wire is already connected to the boat’s DC negative system. The negative generator cable is connected to the generator ground. The generator ground is connected to the generator’s earth ground.

Hope this helps,


Day Tripper

Kevin,marinco Y adaptor

I recently purchased a used cruiser with two 30 amp shore power inlets on the hull, one for the air conditioning circuit and one for the rest of the 120 V electrical items such as battery charger, etc.

All the docks I have been to only have one dockside 30 amp supply per slip.

Is it best to use a marine electrical Y splitter at the boat end of my power cord or to use a Y splitter at the dockside power and run two fifty foot 30 amp cords to the boat?

I realize they are different Y splitters depending on which end I will use them. I’m just not sure which is the best one to buy.


Hi Sean,

Since the dock outlet is only rated at 30 amps, it really doesn’t matter which combination you do.

If you have not purchased the cords yet, I would put the adaptor at the boat and only run one cordset from the outlet to the boat wiring.

Unfortunately, you should plan on a lot of nuisance tripping of the breaker on the dock.


Dead Moomba


I have a 2003 Moomba wakeboard boat.

If I’m out on the lake for one or more hours, the boat just dies. The stereo is on, the heater is on, but I’m dead in the water.

  • I have cleaned all of the boat’s wiring connections for corrosion and changed the ignition relay.
  • The previous owner has eliminated the safety switch cause I can’t find it anywhere.
  • The Shift handle is a little loose, but I don’t think it’s that.

Could it be a heat problem triggering an electrical ground? If it is, I can’t find it. ARGG!

Last time this happened I saw the the alternator meter was at 0. Then if I sit for about 30 seconds it will start sometimes. Other times when I turn the key I don’t hear the fuel pump come on, that’s when I will wiggle some connections, then it will start, but I don’t think that’s the problem.



Hi Joey,

If the fuel pump does not come on when you turn on the key, there is no ignition power on the engine.

Trace down the pump (ignition power wire) and check to make sure 12v power is at the pump – probably powered through a relay. Check the purple power wire to the ignition system. Both locations should have power when the key is on.

Your marine electrical probably includes a low oil pressure sensor. A bad sensor or low oil pressure will cut the ignition power.

Let me know what you find,


Stop Smoking


I tore all of the boat wiring out of my 1989 Champion. I have all new gauges and a new marine electrical switch panel.

When I attempt to hook up the new stuff to the – and + battery terminals, I get big sparks and smoking.

Have you got any suggestions?Smokin'



Hi George,

It sounds like there is a directly short to ground in your marine wiring.

Follow the + wire from the boat battery to the distribution. Check for proper connections on switch lights and crossed connections on gauges.

When you fix the problem, I strongly recommend adding circuit protection at the battery. It will trip before the smoke gets too thick.

Good luck,


Arima Boat Wiring Diagrams

Hi Kevin,

I’m interested in researching the option of total rewire and upgrade of all marine electric components on my Arima Boat. Do you have schematics and or history pin this particular builder that might help in assessing the scope of this project?Arima Boat

My goal was to incorporate complete new wiring and grounding as well as eliminate old wiring from previous owner and install at factory with state of industry tinned marine wiring and boat bus bars.



Hi Paul,

Boat wiring diagrams are very rare. We do not have access to any information for your Arima.

Most people choose to create a harness from scratch using a standard marine wiring color guide and the bulk wire. The other option would be to purchase a snap together boat wiring system from one of our retail sites.

Hope this helps,


Easy AC Outlets?


I am converting a barge into a houseboat/floating home.

I like the Easy Add AC Shore Power system that you designed for your retail marine electrical site, but want/need more electrical outlets to power things like computers, microwave, etc., etc…

Do you have a system that will handle more outlets or can you can you point me somewhere that I can find the information.

Thank you,


Hi Tim,

The complete shore power system can be expanded to as many outlets as you wish.

The limiting factor is the 20 amp main breaker. If 20 amps is not large enough, I would take a look at the panels that are available from Paneltronics. Their systems are not snap together marine electrical like ours, but they do offer a wide variety of AC panels.

Thank you,


House Battery Bank

Hello Kevin,

Thanks for all of your really helpful boat wiring advice.

I am rebuilding my boat battery wiring to add a dedicated house battery system.

I want to use six 6 volt lead acid batteries and want to wire them in a series/parallel configuration – but am confused about how each battery is inter-connected with the one next to it. They will sit in two rows of three batteries each. Boat battery wiring

Would you have a boat wiring diagram showing how to wire this up for six marine batteries?



Hi Charles,

Dedicated house battery systems are becoming more popular in marine electrical and for good reason. They can really help with power management and – more importantly – can make sure that you can start your engines to get home after a long day playing. This is especially true of boat battery wiring that includes an automatic smart boat battery switch.

Here is a boat wiring diagram that should help your with your project.


Mainship Marine Electrical

Hi Kevin,

I hope you can help.

I have a Mainship with two engines, each with an alternator. Each engine is wired to a marine battery switch (1/2/All/Off) and each switch wired to a separate battery bank. The switches have a solenoid between them so that I can start the engines/run the house from either bank.

I’d like to replace my 12 volt fridge and would like it to have it draw from both banks. Can I set up the marine electrical so the fridge is wired to both banks? Or will that negate the separation provided by the solenoid? Maybe I need a selector switch for the fridge?Mainship



Hi Manny,

The simplest solution would be to wire the refrigerator to a separate boat battery switch.

Keep in mind that when the switch is in the All position, you will be paralleling both house battery banks. With this in mind, you will want to you at least the same size boat battery cable that is currently used to connect the banks to the existing switches (positive and negative). Using a small wire would be a potential fire hazard.

A solenoid system could work, but it would be considerably more complex to wire.

Hope this helps,


Bus Stop


I think that I need to add a marine electrical bus bar to my boat battery wiring.

Do you have any recommendations and or an installation diagram – or are these mainly for the boat battery switch systems that you have on your boat wiring store?Marine electric bus bar



Hi Phil,

A heavy duty boat bus bar will work great as a common ground for your entire marine wiring system.

Connect your negative boat battery cables and all of the boat grounds to it. This will reduce the number of battery ground connections to one on each boat battery.

Hope this helps,


Wrong Charger?

Hi Kevin,

I hope you can help me with a boat wiring issue.

On my boat battery wiring, I have two batteries for my trolling motor, a 24 volt Motorguide. They are hooked up20 amp breaker

  • + to motor
  • - on battery to + on 2nd battery
  • - to trolling motor

The on board marine electrical battery charger has connections for two batteries. Do I just hook it up positive and negative on both batteries?

The reason I ask is the in line fuse on one battery was blown as I took it apart today.



Hi Dean,

Most dual output battery chargers are designed to be connected the way you had them.

The blown fuse may just be a fluke or your charger may not be designed to charge your batteries in series. Check with the manufacturer’s recommendations. If they say 12/24 volt systems, then you are good to go. If not, you will need to disconnect the batteries to charge or buy another charger.