Do I need a 16 or 32a Galvanic Isolator?


galvanic isolators ukWhen it comes to Glavanic Isolators, bigger is not necessarily better.

A higher amperage isolator won’t provide any more protection from corrosion than a smaller one.



  • Instead, you should choose your isolator based on the capacity of your electric supply, and that will usually be either 16a, or the far less common 32a.


  • The most important thing is this: You need the isolator to match the connector on the electric supply outlet.


  • You can’t physically connect a 32a isolator to a 16a supply – the plugs won’t fit. Likewise, 16a isolator won’t fit connect to a 32a supply.
In the UK, very few marinas offer a 32amp supply – the vast majority are 16a. There are three easy ways to figure out whether your supply is 16a or 32a.

best make of galvanic isolator1) Read the label on the plug. It will look something like the picture. The part you’re interested in is circled in red. It will read either 16 or 32.



best galvanic isolator for narrowboat




2) Even if the label’s peeled off, you can easily measure the plug. See the photo.

The 32a plug is much larger.





galvanic isolator for narrowboats



3) Look at the circuit breaker. There should be a trip switch close to where you connect into the electric supply. This should have a number on it – typically 16 or 32.