Marinette Boat Forum

Over the weekend my capac reading was at 0.6 instead of the usual 0.9. My refrigerator had quit working sometime during the previous week. The refrigerator breaker switch was off at the panel when I arrived this weekend. It was on when I left the previous weekend. When I push the refrigerator switch on, the panel Amp meter pegs right and shortly after the panel refrigerator switch turns off and the Amp meter pegs left. There is a buzzing sound for about 3 seconds when the fridge switch is turned on before it turns off by itself. The only way I am able to obtain 0.9 on my capac is by disconnecting shore power from the boat. Turning the AC circuit off at the panel makes no difference. I have moved and disconnected the fridge from any electrical connection. Is this just a bad fridge switch at the panel? My Marinette is a 39dc 1985. Any advice is appreciated

Does the fridge work on the 12VDC system?.....Generally there are 3 switches for the fridge (assuming its the original Norcold).
1 on AC panel
1 on DC panel
1 front bottom of fridge

The breaker(s) will trip if a direct short to neutral/ground or extreme Amp draw such as seized equipment.

The buzzing may be coming from the galvanic isolator. Generally they will buzz if voltage is sensed on the ground leg.

Check all shore cord connections for melted/brown connections.

Almost sounds like a couple issues, fridge is "sick" and possible issue with shore power. After checking your power pedestal, check any neighboring power peds for melted cords.

I had a neighbor 2 docks down with a melted cord at the pedestal that caused my isolator to buzz.

First off your CAPAC reading is NOT related to an AC issue. Readings will fluctuate with water temp, marine growth on Anodes and of Cathode.
Also loss of shaft isolation will drop you readings. AC leakage may effect readings. Remember CAPAC readings are NEGATIVE VALUES.

You you a serious ground fault! It is not uncommon for a refig to corrode resulting in a short to ground internally. Water Heaters are also common sources for ground fault.

1. Take refrig off line!
2. Inspect all AC electrical connections breakers etc for corrosion and poor connections.
3. Your galvanic isolator is buzzing because current bleeding into the circuit at a higher rate than it can handle. There is always some DC current on an AC line. The Isolator prevents DC current from running on your AC Neutral.

4. Battery chargers can also be cause of AC bleed especially if they are not approved for Marine Use. Automotive chargers are not well isolated.

I have a stray current tester that floats and will sound alarm if there is stray AC current. I use it several times a year around my boat and every season when I start our pool up.

I would also suggest that if you have not done this is to replace our AC outlets with GFCI outlets. Run your circuits in series so only one GFCI outlet will protect all outlets down stream.

This is a serious safety issue!

And the followup on the original post is...?????

Thanks for asking on a follow-up. Summery: With the refrigerator and ice maker plugged into the same ac outlet on the boat and with shore power plugged in, turning on the refrigerator circuit breaker switch would cause the capac to buzz for 5 seconds and turn the circuit breaker switch off. Capac readings are at 0.6 when on shore power. With both appliances unplugged from the ac outlet, the refrigerator circuit breaker switch will stay on without any buzzing from the capac. The capac reading is still 0.6 with shore power plugged in. The only way to return capac reading to 0.9 is to remove shore power hookup. I asked my marina who were M dealers back in the day, to look into the problem and unfortunately they were to busy with hulling out boats. So, my M is now on the hard, winterized till spring, with the problem unsolved.

Go back and read other threads here on the CAPAC and the blocking transformer. It has been explained before. You have to understand what they do and how the Capac cell works and is not part of the 12 VDC or the 120 VAC systems.

Separate (almost entirely from the AC item) is it possible there's a DC short on the fridge that gives the CAPAC the willies because the short is setting up a galvanic issue. ? Just pulling something out of the air. Really unlikely but who knows. (also seconding that CAPAC has nothing to do with AC systems)