Isolation Transformer Install | Sailing Blog - Technical Hints and Tips - Sailing Television

Isolation Transformer Install

MasterVolt Isolation Transformer Install
Yesterday was spent getting things back in order on board, and installing a shiny new Isolation Transformer! This one is a MasterVolt IVet D - Multi-tap

Why is an isolation transformer a good idea?

  • Galvanic corrosion can be a problem on all boats. This means stray DC currents coming onboard through the ground when you connect to shorepower. The DC currents can easily dissolve metal fittings on your boat that are in contact with seawater - or even the hull itself if you have a metal hull. Yikes!
  • Shorepower can be incorrectly wired in different marinas. For instance we have seen power where both legs of 220 volt power was live with 110 volts each! Interesting but not correct. Without the transformer we could not connect safely to this supply.
  • 110 or 220 volt - we use the Multi-tap transformer to convert from one to the other so we can plug in anywhere around the world

MVolt Case
An isolation transformer means the shorepower ground wire is not connected directly so there is no stray DC current entering the boat and no galvanic corrosion.

MVolt guts
The second reason to have a transformer like this is to be able to connect to either 110 or 220 Volt power. This kind of transformer is called a Multi-Tap transformer and allows us to connect to either of the world power standards. When connecting to power here in Europe we need accept 220-230 volts. In north America we will need to take 110-120 volts. In this case I can slide the green switch on the right of the photo) down to accept 120 volts. The transformer will take in 110 volt power and convert it to 220 volts (note it will not convert the frequency - so we will have 220Volt 60Hz but this is fine for most appliances)

MVolt bulkhead
This is 28kg piece of equipment. It needs a solid bulkhead to mount it on. Note the books piled on the floor underneath the spot... this means I can lift it in and sit it down on the books as I manoeuvre it into place.
MVolt paul lifts in
MVolt installed
Hanging in place - ready to be connected

DISCONNECT shorepower before working with any boat wiring!!!

I cut the shorepower input line and connected the transformer. If you are at all unsure of how to work on wiring you should have an electrician do this part.

Now to test it.

Everything works fine. We are in business.
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