House boat grounding and bonding

electro7

Senior Member
Location
CA, US
Hi,

I was planning on taking on a house boat solar project but have been a little cautious about it after reading all of the water drowning electrocution death articles. I was wondering if somebody could give me some pointers on how to properly ground or bond a boat?

First, I was talking to a guy today who said to use a "galvanic isolater". Is this what I should use? I guess it acts like a type of capacitor. From the incoming shore power the EGC is broken and lands on two of its terminals. The house boat currently does not have this installed. The rest of the wiring system is in place and I was going to add the solar to it with a new inverter etc.

They said that there has been a lot of electrolysis around the dock causing a lot of boat pontoon corrosion. One guys said he measured half a volt in the water. Should I be concerned with this at all? In order to wire in the solar I was told I may need to swim under the boat. I am a little concerned with that knowing there is voltage in the water. I still may try to keep it so I would not have to get in the water to wire it.

Thanks for any help you can offer!
 

kwired

Electron manager
Location
NE Nebraska
Shore power to the boat or dock is the biggest concern that introduces electrocution hazards in the water around the boat or dock.

You can do everything right and still have voltage to true earth on surfaces that are bonded to the electrical grounding system because of voltage drop in the service conductors or even back at the POCO's MGN of their distribution system.
 

electro7

Senior Member
Location
CA, US
I am not sure much about the "Galvanic Isolator". I just saw one on another boat. It looked like a capacitor sort of. The EGC from shore power was interrupted there and landed on two terminals on the galvanic isolator, if that makes sense. The guy I spoke with is an old EE and recommended it be installed on the boat I'll be working on.

There is shore power that the boat is plugged into while docked.
 

cuba_pete

Senior Member
Location
Washington State
Galvanic current voltage levels are typically below 1 volt. A basic galvanic isolator contains diodes which limit the voltage flow but do not restrict fault current.

Since you would essentially be placing an electrical device between the service and the boat, your local AHJ should have more information about the application and limitations.

Your boat makes up one terminal of a (saltwater?) battery, the EGC from shore being another. Parts of your boat are at different potentials, bonded or not. Those very low voltages developed through galvanic currents slowly eat away at every metallic structure in the path.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
I expect he is talking about a galvanic isolator installed in the boat on the shore power EGC. The following is from a boating source.

The most common way to reliably and safely interrupt the circuit is to install a galvanic isolator. Galvanic isolators attach to the green grounding wire to limit galvanic current flow (up to about 1.2 volts) between neighboring boats while also allowing dangerous AC current to safely pass through to the ground on shore.
 

GoldDigger

Moderator
Staff member
It is typically a pair of diodes, but it could be any other device with a breakdown voltage less than about 10V.
POCOs use essentially the same thing and call it a neutral isolator.
 
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