Electrical leak from refrigerator

[Helmsman]

Last summer, I was getting a prop changed via a diver. I cut the shore power off. He noticed a slight electrical current coming off the rudder. I have my outlets running through a Promariner ps2000 inverter charger. The inverter was on, though the only thing running was the fridge. I realized I hadn’t cut the inverter off. Once I cut it off, the current stopped.

I have been concerned about the leak, since reading on here and elsewhere about the danger of Electric Shock Drowning (ESD). I called the guy who helped install the inverter, and he was no help. I called ProMariner and they sent me a 12 step diagnostic routine, which revealed nothing. Last October, I had the boat pulled at a local marina to look at a couple of areas. While there, I had their electrician look at the wiring to see if he could find anything. He put a jumper between the ground and Neutral buss bar and pronounced it fixed.

When I returned to my dock, his wire caused my breaker on the panel at the house to flip. I removed his wire, and the breaker worked. ABYC certified electricians are few and far between in these parts, so I figured I would have to figure it out. It didn’t flip the breaker at the marina. They probably use the new ELCI breakers there.

So, I read Nigel Calder’s book (the 6 or 7 chapters on electrical about 6 times!), and read everything on this site that was remotely related, and worked my way through the boat looking for issues. The bonding system looked good. The connection between the bonding system, the DC negative, and the AC ground was proper, and I found no wires in either panel loose, crossed, burnt, etc.

The next step was to look at the wiring in the panel for the inverter. The inbound wire from the inverter was properly wired, the neutrals were on a separate buss bar, and the line in (power) for the circuits was segregated for those circuits on their own bar. I noticed that when I checked for continuity between the inverter neutral bar and the ground bar, I got continuity. That made sense, since the inverter is a power source and the neutral and ground are tied together only at the source (just like the generator and the shore power connections).

The next step was to pull the neutrals off and check for continuity between each one and the ground bar. The inbound inverter line showed continuity. Three of the circuits had no continuity. The refrigerator, however showed continuity. That indicated an issue with the power supply to the fridge. I pulled the fridge, pulled the plug from the outlet, and checked for continuity. There was no continuity. So, it wasn’t the circuits. It was definitely the fridge. I have a 2006 Nova Kool rfu9000. It has a power converter (converts AC to DC) that is no longer distributed. That was the culprit.

In a discussion with Nova Kool, they told me there should not be continuity, but since they no longer carry the power converter, they couldn’t help. A little research on line showed that Danfoss has the DC control unit I was using.

One option was simply to pull the power unit, and run the fridge directly off the DC feed. That wouldn’t work for me, as the inverter purchase was due in part to spread the power usage amongst two battery banks.

The second option was to replace the 101N0210 DC only control unit, with an 101N0510 AC/DC control unit. Doing that eliminates the need for a separate power converter. So $266 later, we have a fridge that is working with both AC and DC. And there is no longer an issue with continuity between the neutral and ground, nor is there a small electrical leak coming from the boat.

Thought I would post this here, due the fact that the Danfoss 35 and 50 compressors with those old power converters and control units are ubiquitous in the boating world, and are easily updated with the control unit only option. Someone else may benefit from this since everything I read is that the Danfoss 35 and 50 are almost indestructible and can continue service.

Page 5 shows the different control units.

http://www.novakool.com/support/documen ... pdated.pdf

E991F638-E032-4FA6-A0A6-730014C70851.jpeg

Unfortunately, the picture is upside down for some reason on this post. The power converter is the silver box on the left. The 101N0210 control unit is between the converter and the compressor. The new AC DC 101N0510 control unit fits where the 0210 unit is in this picture.

[Midnightsun]

Excellent info, thanks for posting.

[Viper]

Good job

[bud37]

Great post, a perfect example of how tricky it is to troubleshoot marine electrical, it is just not the same as the house.....Good catch , man.

[Hugo]

You can replace the AC/DC power supply with a MEAN WELL 12 amp power supply for $20 (MEAN WELL LRS-150-12) and use an automotive relay ($5 - $8) to switch power to the fridge between AC power or DC from batteries depending on what's present. This is a bigger power supply than we need (fridge draws 4.5 amps or so) but it won't work as hard. The boxes on the back of the refrigerator are way over complicated...