Sacrificial shore power connector?

[Kevin]

We had some wind come up at the marina sufficient to tighten up the mooring lines and let the boat move a bit more than I had allowed for.  All the lines have a bit of spring and no problems with the exception of my shore power chord.  It worked up enough slack to allow about 3 feet of its length to be immersed in the salt water.  I have no idea how old the chord is, but the boat has a lot of support equipment that has been in use since her launch 24 years ago.

The chord could have been in the water for as long as two weeks.

When I got down to visit her there was no 110 power inside but it also looked like none of the breakers had tripped.  After disconnecting the shore power chord and a general lookover I turned on the inverter.  All the 110 systems were functioning properly.  Voltage steady and all looked good.

I replaced the shore power chord with a spiffy new one, this time with this cool reassuring LED that lights up to show the chord has power.  Power through the chord, but nothing inside.  So now I take a closer look.  The boat is equiped with an isolation transformer.  I touch one of the wires coming from the shore power connector and it crumbles to dust.  Some green corrosion on the copper wire ends that remain.  I cut the wires back about 1/2 inch to make sure I had shiny clean wire.  All looked good so I hooked it all together again using a wire nut for the test.  The system comes up and all functions correctly.  I ran a heavy load, refrigerator, freezer, water heater, cabin heater overnight checking at intervals and there was no sign of any warmth or cause for concern.

Now my question.  It seems like that connection was of some sacrificial material.  It's like it was intended to dissolve in just this kind of situation.  Does anybody know if such a connector exists, what I'd call it and where I'd get it?  I spoke to a salesman at West Marine.  He said he had such a connector on the water heater in his boat, but that West Marine doesn't carry them.

Any suggestions?

[kevin barber]

I know of nothing like that.  Chances are that they were just VERY old connectors that were made of standard copper, rather than marine grade tinned copper.  I have seen many outdated components installed in the electrical circuits of many older boats that have connectors that have corroded off.

I can't think of any reason why you would want a sacrificial anode in line on your AC inlet wiring.  Your bonding system should allow galvanic corrosion to happen on your shaft zincs.  I suppose you could call a fuse a sacrificial anode, but a breaker would be better suited.   I believe that ABYC standards now require new boat manufactures to install a breaker within 4 or 5 ft of the AC power inlet, then another breaker on the main distribution panel.

[Kevin]

Thanks for the reply.  For sure the "disappearing" componet was old.  It had dissolved to an unrecognizable lump.  The idea of adding a breaker like you describe near the shorepower connection seems like a good idea.  

With the isolation transformer if I understand my boat's setup (and I for sure don't really) it's like there is a separation between the shorepower side of the transformer and the boat circuits side of the transformer with no connection between.  If true then the boat's zincs are not providing any protection to the isolation transformer and anything between it and shorepower.  There also is no breaker of any kind between the shorepower and the transformer.  With shore power connected If I shut off the boat's main AC breaker the transformer continues to hum with power connected.  The only protection is the breaker at the dock.

[SV THIRD DAY]

The above photo show my shorepower connection and also my Guest Galvanic Corrosion Inhibitor.  The ground from the shorepower first goes through the unit before tieing into the ships ground.  This keeps the flow of current comming form the AC shorepower from going to the DC ground and eating away my zincs, prop, shart, strut..etc.  It is a 30AMP unit, easy as pie to install, I bought it from Jack Rabbit Marine where I have purchased all the electrical components for THIRD DAY's refit.  It wasn't cheap at $155, but after losing a strut and shaft to galvanic corrosion....well...you don't even want to ask how much that cost!



Guest Galvanic Isolator, 30A

Guest galvanic isolators protect your boat from galvanic erosion and metal loss.

Product Features
* Prevents the elctroplating action that occurs on boats with AC power feeds
* Blocks DC current from flowing into the water
* Passes necessary AC ground current for shorepower safety
* One year warranty