All, Sorry in advance for the long post. I had a rather strange experience today. I have been in the process of upgrading the shore power system on our N28-2. So I get the old panel such as it was removed, enlarge the opening for the new Paneltronics panel, run a new 10ga wire from the shore power plug to the panel, and hook it all up. I temporarily hooked the old outlet wiring to the new panel for testing. Everything was looking good. Plugged in one of my power tools, and turned it on. The circuit breaker immediately tripped, as well as the main 30A breaker. As the breaker tripped, the reverse polarity LED lit. So , back to the shore power plug. Verified it was wired correctly. Checked the wiring at the panel, which was also correct, restored power, and tried again. Same result. Both the circuit and Main breakers tripped and the reverse polarity LED was lit. Got out the DVM., Thinking that the marinas power was faulty. Started checking voltages. Checked the voltage at the panel, saw 120 from hot to common, and also to ground. That looked good. Checked the voltage between common and ground, and saw about 60v. Now that should not be. So I scratched my head a bit, trying to figure out what was wrong. Checked the voltages at the end of the shore power cable, and got the same voltages. Ok, so I think to myself, that the marinas power has a problem. Check the voltages at the marinas plug in, and found 120v from hot to common, and to ground, just as it is supposed to be. Checked the voltage between common and ground, an it was 0v. Again just as it should be. I had brought a new shore power cable to replace the old cable that came with the boat. There was nothing visually wrong with it, but I had a new cable I had purchased for the CM26 I rebuilt last year that I wanted to use. Plugged the new cable in, and everything worked perfectly. Able to plug in power tools and run them without the breakers tripping. So with all of that said, there appears to be a high resistance short between the hot and either common or ground in the old shore power cable. The resistance is high enough that it does not trip the marinas shore power breaker, but it lets enough voltage pass to trip the voltage actuated breaker in the new AC panel. Anyway, I figured that you guys might want to know about what I discovered today. I will take the cable ends off in future and see if I can see what is causing the voltage issue.