first of all your boat doesn't have a 120/240 split system. 30amp shore powers are 110v. you have to have a isolation transformer, but you would need two. and connect the neutral and ground on the secondary side.
Sep 08, 2007 Rating
GFCI & AutoTransformers by: Nate
The root of your problem with the dock breaker tripping is most likely that the transformer you have selected is an autotransformer. Autotransformers have a common primary/secondary winding, thus forcing a connection between ground and neutral on the boat side when wired correctly. If this is the case, you must replace it with an isolation transformer. In wiring, be sure that the incoming safety ground is connected to the transformer case and the boat's safety ground IS NOT. The boat's safety ground is connected to the designated neutral at the transformer secondary. A transformer secondary and a generator are the ONLY places on a boat where a connection is made between safety ground and neutral. Your boat has a split 120/240 volt system, so your transformer must have a 120/240 secondary winding.
Incidently, there SHOULD be ONE connection between the main busses of the boat's DC (-) and AC safety ground.
Sep 08, 2007 Rating
Shore Power Solution by: Frank
I just popped in after years of absence and saw this post.
The RCD or GFI detector works on the measurement of current flowing from the live wire to the load and back through the neutral wire. If a difference or loss of current exceeds 30milliamps there is an unbalance and the RCD trips. it is assuming this missing current is electrocuting someone!
It is possible you have the earth and the neutral bonded together at the transformer primary. It is common practice to join earth and neutral. The reason being it 'ties' the neutral to zero volts and stops it floating.
This is because the only place the neutral is at zero volts is at an earth point.
What you are experiencing is current going to earth and not going back through the neutral. Just check with multimeter if neutral and earth are joined at the shore plug.
As for the frequency it causes problems with synchronous equipment such as AC clocks and completly changes the impedance of electric motors.
