Archive for the ‘Generator’ Category

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,


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,


Euro boat on US shore power?

Hi Kevin

I brought my sailboat from Europe with me when I came here to work this year. The marine electrical is completely European spec, i.e., 220VAC-16A-12VDC. I am wondering how I can plug in to US shore power at marinas here in the US.Marinco adaptor

I do not want to completely change my boat wiring as I will eventually be returning to Europe. Also I am not a heavy user of power, I could cope with just keeping the batteries charged up.



Hi Paul,

Some of the AC components on your boat may be able to cope with the change in voltage and frequency, but not all of them and the solution is not as simple as adding a transformer to increase the voltage.

If you only want to charge your batteries, I would buy a simple battery charger and charge your batteries with an extension cord while the boat is in the states.

Good luck,


Houseboat Grounding


I have questions on grounding both the 12 volt and 120 volt marine electrical on a houseboat. I have read the old threads regarding this matter but I am still thoroughly confused. Sorry that my post is long, but I am trying to explain clearly but simply:Boat Wiring Store has marine electrical products for your boat wiring project

Here is my set up:

The boat is 1976, steel hull. It has a shore power connection but because I am on a permanent mooring I do not connect to marina’s shore power.

Here are the original marine electrical systems and the boat wiring:

  1. 12 volt starting battery. Hot goes to engine starter and Negative cable on this battery is also landed at the engine. In looking how the engine is mounted, I don’t think that the engine (outboard) is isolated from the steel hull / frame.
  2. 12 volt house power: hot and negative battery cables go to marine electrical bus bars for each. These bus bars (hot and negative) then go to my 12 volt distribution panel, and to my 12 volt stereo/amp system. This 12 volt house system is not grounded anywhere that I can see. Question: Should it be grounded?
  3. 120 volt AC shore power system: Plug connection goes to a distribution panel. Typical 3 wire set up: Hot (black), Neutral (white), ground (green). I have not looked to see if the ground or neutral buses in this distribution panel are grounded anywhere on the boat. I don’t think it is, but I need to look again. Question: Should this be grounded? Because I am on a mooring, not in a slip, I never connect to actual land based shore power. When I do use this connection it is via my own portable generator on the boat. Fire up the genset, run a 30A shore power cord from gen. to shore power plug.
  4. New installation: I have connected a small 700W inverter from my 12 volt system just to run a few items (tool chargers, 120 volt rope lights, etc). The inverter has 2- 120V receptacles, no hard wire 120V. In the past I have plugged in an extension cord from the inverter to my rope lights. But, now I want to connect my rope lights through a permanently wired receptacle. I connected a 3-prong utility type cord (male plug on one end and open wires on the other). Intent to be to run this cord into a J-box where I could then run in conduit and wire to a switched receptacle for the rope lights. Funny thing is that when I checked the power coming from the 120V cord I get the following readings:
    • hot – ground: 110V
    • neutral to ground: 95 – 105V
  5. Is this correct? Shouldn’t this be 0 volts?

Everything works fine, but is this set up correct?
My biggest questions are: How should 12V system be grounded, How should 120V shore power be grounded (even though it doesn’t go to land based source), and is inverter power with current going through neutral correct?

Thanks very much for any help or clarity you can provide.


Hi Paul,

Regarding each of your boat wiring questions:

  1. You are correct. The engine is not isolated.
  2. The negative from your house battery should be tied to negative on your starting battery.
  3. Your AC ground and DC ground need to be connected to give a low resistance path to ground in the event of a major fault.
  4. Should be 0 volts.  Neutral and ground should be tied together at the inverter.
  5. AC ground should be connected to DC ground.  You should have a voltage reading of 0 Volts between AC ground and AC neutral.

I hope that this is helpful.