Shore power earth

[colind3782]

The earth from the marina shore power goes via the RCD to a galvanic isolator. Where should the “output” side of the GI go to in the absence of a hull anode on a GRP boat? The engine block is an option but the DC negative goes to the block at present and it doesn’t seem right. I’ve searched old “shore power earth” threads but can’t find an answer. I would just as soon not make another hole in the hull for an anode. The shore power is never connected for more than 2 or 3 weeks at a time as we disconnect when we’re not there.

 

[PaulRainbow]

The earth from the marina shore power goes via the RCD to a galvanic isolator. Where should the “output” side of the GI go to in the absence of a hull anode on a GRP boat? The engine block is an option but the DC negative goes to the block at present and it doesn’t seem right. I’ve searched old “shore power earth” threads but can’t find an answer. I would just as soon not make another hole in the hull for an anode. The shore power is never connected for more than 2 or 3 weeks at a time as we disconnect when we’re not there.

The load side of the GI connects to the Earth busbar (often found inside of the consumer unit). All outlets and equipment Earths also connect to the same busbar. If a connection to the water is made, that is also from the busbar.

The connection can be a metal hull, a ground plane or an anode. If there is no hull anode it's probably going to be pointless connecting to the engine, unless the engine is connected to the water via the prop shaft. So check for continuity between the engine and the water, if it exists, you can connect to the engine block, it won't matter that DC negative is also connected to it. If no connectivity, you need to fit a small anode, it can be the smallest one you can find, it isn't acting as an anode, it's just connecting the Earth circuit to the water.

 

[Bodach na mara]

With no anode, do you need a galvanic isolator at all?

 

[colind3782]

The load side of the GI connects to the Earth busbar (often found inside of the consumer unit). All outlets and equipment Earths also connect to the same busbar. If a connection to the water is made, that is also from the busbar.

The connection can be a metal hull, a ground plane or an anode. If there is no hull anode it's probably going to be pointless connecting to the engine, unless the engine is connected to the water via the prop shaft. So check for continuity between the engine and the water, if it exists, you can connect to the engine block, it won't matter that DC negative is also connected to it. If no connectivity, you need to fit a small anode, it can be the smallest one you can find, it isn't acting as an anode, it's just connecting the Earth circuit to the water.

Thanks Paul! ??

 

[colind3782]

With no anode, do you need a galvanic isolator at all?

I wasn't sure but I thought it can't hurt.