Re: [Amel Yacht Owners] Upgrading all electronics
Bill Kinney <greatketch@...>
I am assuming what you are seeing is a AC voltage. If it is DC, then the analysis would be different, starting with faulty wiring cross connecting your DC system with your bonding circuit.toggle quoted messageShow quoted text
What you describe can be potentially very dangerous for swimmers in the water. http://www.boatus.com/seaworthy/magazine/2013/july/electric-shock-drowning-explained.asp
As a first question… Are you sure the problem originates with your boat? It could be from a neighboring boat, or from the wiring in the marina itself. It is possible in salt water the only time you would feel the shock from some other source is when you touch metal on your boat AND your boat is connected to the marina earth connection. If from some other boat there is nothing you can do other than move away!
If the voltage does originate on your boat, it comes from a combination of two problems. First, a ground fault in some piece of equipment leaking current into the bonding circuit combined with a break (or high resistance connection) in the ground wire somewhere between your boat and the earth connection in the marina. A potential candidate for the leaking current from inside your boat is the water heater. If the heating element is beyond it’s service life it can short to the shell, and then to the bonding circuit. If you turn off all electrical appliances at the circuit panel and turn them on one by one you might find a culprit. If you already did this and it is the reason you suspect the battery charger, then you are a step ahead of me!
If you have a ground fault from some piece of AC powered equipment, it will leak voltage into the bonding circuit, where it should travel back to the earth connection at the dock by the ground wire. The galvanic isolator blocks small voltages (typically from DC current leaks) and passes high voltages (safety issues). Typically, these show a voltage drop of about 1.2 volts or so. If this is what you are seeing between the water and bonded metal on the boat, your grounding system might be doing what it is supposed to, but you still have a ground fault with something onboard.
The isolator should be connected in line in the ground wire between the shore power connection and any other connections on the boat. Can you test it as suggested in the manual?