Re: [Amel Yacht Owners] Upgrading all electronics
Bill Kinney <greatketch@...>
Kent,toggle quoted messageShow quoted text
It’s not simple…
Connecting the charger safety ground can be done to either the AC safety ground wire, or the bonding wires, assuming the bonding wires are big enough to take full current from the AC system. Since those two systems are interconnected, they are are pretty much the same.
There is no “DC Ground” as you seem to think of it There is only a DC negative. The reason for this is that 24Volts is not going to kill you, although, DC current running around on you boat can cause havoc as you well know!
Stray DC current certainly is the culprit in electrolytic damage. “Stray” AC current isn’t so much a corrosion issue as it is a serious safety problem. The issue when connected to shorepower is DC currents that flow over the AC Safety Ground wire when plugged into shore power. In this case every boat in the marina is grounded to the same point on shore. Any problem on any boat can result in DC currents flowing between boats, through the water and back on the ground wire.
Now it gets more complex… electrolytic and galvanic corrosion are not exactly the same, although people frequently use the terms interchangeably.
Electrolytic corrosion is caused by imposed electrical currents. Galvanic corrosion is caused by an electrical current generated by the presence of dissimilar metals in an electrolyte. No external voltage source is needed. Galvanic voltages are low, usually less that 1 volt and are blocked completely by a galvanic isolator (hence the name…) Stray currents can be up to 24 volts. If they are greater than about 1 volt the galvanic isolator does not work.
One other difference. The isolator blocks galvanic action between different boats. It will not protect you from electrolytic corrosion caused by stray current generated by your OWN boat that do not flow through the AC safety ground wire. And an isolator does nothing at all when not in a marina.