matthias-nagel avatar image
matthias-nagel asked

Connect PE of on-shore power with PE on boat?

The minus potential of the DC system on the yacht is grounded. In particular, the minus terminal of the alternator is connected to "ground" (i.e. sea water) via the engine and the drive shaft as well as the minus terminal of the windlass via the chain cable.

The AC connector for on-shore power is IEC 60309, L+N+PE, 6h. (In German that connector is colloquially called "Campingstecker".) This connector also provides a PE and is connected to on-shore ground.

I plan to use a VE Phoenix Smart for AC/DC conversion and battery charging. The Phoenix Smart does not require a PE.

I am wondering if I should connect the on-shore PE with the yacht's PE.

Intuitively, I drew that connection into my wiring schematics, because it felt wrong to leave the on-shore PE unconnected and as a dead end.

On second thought, I figured that it might be a bad idea. If the on-shore PE potential was different from sea-water potential, equalizing current would run through the minus conductor of the yacht.

Of course, normally the on-shore PE potential should be identical to the sea-water potential. Everything else would mean that the on-shore electrical system is faulty. But who knows?

Any suggestions or recommendations?

GroundingPhoenix Smart Charger ip43yacht
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1 Answer
pwfarnell avatar image
pwfarnell answered ·

If you connect the shorepower PE to the boat PE then you should have a galvanic isolator installed to avoid galvanic corrosion if the shorepower PE and seawater are at different potentials. If you are connected to shorepower and the boat next to you is also connected, then if the metals in the seawater are different on the 2 boats then you have a battery circuit between the 2 boats which will cause corrosion. An isolation transformer is better than a galvanic isolator but is probably more than you need for your limited installation.

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