Low House Voltage

Help me understand some electrical issues. I'm only getting 97 to 100 volts at the 120 volt outlets throughout the boat with or without loads, and 200 volts at the panel. At the shore breakers, I get 114 to 117 volts per side, but only 200 volts between the two hot sides. Is there a phase issue at the marina here?

Shouldn't the isolation transformers convert the shore power to reliable voltage or is that too much to ask?

I still can't figure out why I have two 50 amp 240 volt shore cables (each port and starboard) but the Ship Service meter only shows one (port or starboard). I tried turning off one at a time at the dock and different items operate from each cord but the panel only sees one.

If the issue is the line voltage I'm only temporarily in this marina but it is cold here, 12 degrees last night, and I don't want to run the compressors with low voltage.

By the way, everything works great off the generator, 120 volts at 60hz at every outlet.

Thanks!

I would say you have corrosion on terminations somewhere. Corrosion is a resistor and if great enough will reduce voltage. Best thing to do is to use a good meter and read voltage at the shore power, end of your cord, next, next, untill you find the voltage drop. I bet that when you find the issue it will be visually obvious as well. This is electric "101" and you can do it yourself. Even if the repair is beyond your ability and you need to hire out for repairs you will save on the troubleshooting.

Sounds like 208v shore power. It will show approximately 120v per leg or 208v between any two. Add to that the voltage drop because of the length of run from the transformer and the load that others are drawing and you have just what you describe.

The Isolation transformer will boost the voltage, but only if they have been equipped with the proper switches to change the taps on the transformers.

There should be a voltmeter for each shore "Source" as well as another meter on each "ships service".

Hatteras will supply the diagrams for adding the switches to boost voltage at the Isotrans if you don't have that already.