Blowing the circuit on the dock

[mestrezat]

Here's a tough one for everyone because some times it does and sometimes it doesn't. We are out in Malaysia and have to use a step down transformer to decrease the voltage from 220 to 110. When we pull into a marina and the electrician comes and hooks us up to shore power, when we flip the switch inside the boat, we blow the circuit breaker on the dock. When we were in Kudat, they hooked us up the the power circuit for the boats in the yard. Same thing yet when they hooked us up to the main circuit panel for the yard, we had nice 110(out of the step down transformer) and when we flipped the circuit panel switch, all was fine. We had 110 power. Same wire. When I use my generator, the electricity comes into the boat through the same cords and it charges the system just fine.
When we were in the Philippines, we found that they don't use a standard ground wire like they do in the US. The step down transformer I brought from the US required it so I had to buy one made in the Philippines with only two prongs on the plug. It worked fine while we were there but the one from the US would not work. Our wiring worked just fine while we were in Fiji(almost a year).
What confuses most people is that it works when on our generator(same wires)but not on shore power, plus in some places it works and others not.
Some times when we connect the wires to the marina panel, we have the "reverse polarity" light come on on our circuit panel. We reverse the two wires and all is fine yet the circuit breaker on the dock still blows when we flip the switch.
Anyone got any ideas as to what is going on. Everyone out here keeps making suggestion but we have already tried what they are suggestion.

[mrm]

Is your step down transformer equipped with a soft start circuit?

[sailorchic34]

Is the dock power two wire or three (with ground) I'm assuming three and that the wiring standards are off on the dock., IE they have one leg tied to your ground, so blows the breaker. It also could be a fault dock breaker. Breakers do go bad once and a while. But I'm betting the dock wiring is off. Seen that even in the US.

[Neptune's Gear]

I agree, Polarity problems and earth leakage are common (virtually normal!) in SE Asia. Its either that, or possibly just your shore power is drawing to much for the docs circuit breaker - some units can limit their max draw to suit the dock setup - can yours?

[Nicholson58]

Transformers have a large inrush current until the field is built. This is sort of like a short. We sometimes trip out too but it helps to turn off the boat switch until the transformer is powered.

[Lancerbye]

In South East Asia I have found 240 volts range anywhere from 180 volts to 260 volts. A normal load will appear too high if the voltage is too low. An ac regulator which soft starts the transfer of power to your boat and maintains the 240 volts may be a worthwhile investment. These are very common in the Philippines and the mechanical ones are better and not as expensive. Put it between the shore power and the step-down transformer or get one that has 120 volts tapped out as a normal power outlet to the circuits you want to use.