Generator and Electrical systems grounding on a Houseboat

120 volt and 12 volt electrical grounds?

120 volt and 12 volt electrical grounds?

Can you have a 12 volt electrical system and a 110 volt generator system use the same grounding wires in an aluminum hulled houseboat?

It seems like it would help create electrolysis with the 110 volt green grounding wire attached to the 12 volt negative ground going to the engine and therefore the aluminum hull. Maybe I am just over cautious.

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Reply - Answer
Well, that's an excellent question that hopefully someone better qualified than myself will answer. (is there a marine electrician out there?)

After years of research on the internet, I have never been able to find a concrete explanation on how & where to connect the "ground" from a generator.

The exact scenario brings be back to a situation with a neighbor that had an aluminum houseboat. He was also wondering whether to connect the generator ground (not the hot or neutral wire) to the hull or to the 120 volt ground.

He had an galvanic isolator installed on the ground wire of his 120 volt system. The negative or ground side of his 12 volt battery banks were connected to the aluminum hull.

We wondered if he should wire it to the hull, or wire it to the 120 volt galvanic isolator ground green wire side.

My neighbor ended up connecting the generator ground to hull, and used his generator for the rest of the year. Unfortunately he moved away and I never was able to get more feedback about it.

For a better answer, hopefully one of our knowledgeable Marine Electrical readers will share and post comments about their houseboat 120 & 12 volt experiences.

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Comments for Generator and Electrical systems grounding on a Houseboat

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Keep them separate.
by: Amsterdamhouseboats

Disregard the battery charger company diagrams, what the posters above said was absolutely right.

Aluminum boats are particularly vulnerable to stray current corrosion, keep all grounds away from the hull.

It can be difficult since so many machines have "earth" attached to the case, which is hard to isolate from your hull. You should only use marine electric equipment to avoid this.

I'm not so strict about this with my steel hulled boats; but I do use an isolation transformer to galvanically protect myself from my shore power line.

Those "galvanic isolators" only work up to a couple of volts, then your hull starts to dissolve.

DO NOT connect shore power earth to your aluminum hull, and you really should have an isolation transformer for it [they're big, heavy, expensive, and they hum].

Do not ground the 110 volt to aluminum hull
by: Anonymous

A generator on an aluminum hull boat should be ground to the engine block not the hull, and the generator insulated from the hull.

A RCD or Residual Current Device (ground fault circuit interrupter (GFCI), ground fault interrupter (GFI) or an appliance leakage current interrupter (ALCI), should be installed in all circuits and if you wanted to go the extra mile then install an earth detection alarm.

Correction on grounds
by: roy

I should have stated blue on pos DC. Any switchlegs should be marked DC+ or DC-. Of course if you are rewireing its easy. If you are marking old it takes a lot of traceing.

Also the green grounding theme anonymous suggested is the way to go. The frame on a generator is metal it should be grounded but not the DC neg. Never.

As far as the green ground on the battery charger never seen it. Call the manufacturer. I know where, but they can tell you.

Houseboat electrical grounding for AC or DC
by: roy

Don't confuse grounding with dc negative. Ground is ground. Any device that operates on AC power that has a conductive surface should be grounded. This is for your safety.

Negative is negative. It provides a loop for dc powered devices to operate. The individual that posted green grounding system. Your 100% correct. Also try to mark all wires DC or AC.

Keep them independent of one another. If possible once the wires leave your battery or 12vdc supply, keep them the same color. I prefer blue.

Common vessel AC & DC grounding on houseboats
by: Anonymous

AC & DC systems need to be separate, dedicated systems that are isolated from each other. One reason is that the black hot AC lead will not be confused with a black, ground DC lead.

Also with aluminum vessels you can create an electrical path that will set up galvanic corrosion and you will have a hole in the bottom!

What you need is a common "bonding" (green) lead that runs the entire length of the vessel and ALL grounds are attached to this bonding lead that terminates at the transom and is connected to an exterior zinc bonding plate and it is the sacrificial component of the ground for all systems.

Grounds on Aluminum Houseboat Hulls
by: Anonymous

Thanks for the reply. I have found a battery charger company that has wiring diagrams with the green 110 volt ground attached to the 12 volt negative battery ground in several drawings.

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