Although the photo below is upsidedown it illustrates the problem.
Recently seen on a boat.

The male fitting shown is on the inboard (boat) end of a shore cable connected to a marina 230 volt supply. The conductors are therefore live and consequently lethal. The appalling thing is that the non-technical owner didn't even realise the danger! It was not the installation provided by the builder but was allegedly installed by a certified electrician.

Hi Steve
Interesting that you mention an isolation transformer as as safety device for reverse polarity.  We contemplated fitting one as we have an aluminium boat but given both the weight and cost we went for a galvanic isolator - does this provide the same safety feature and therefore do I need to carry on testing for reverse polarity?  Disclaimer - in the event that I electrocute myself or some-one else you will not be held accountable by me ... cannnot speak for the missus though ...

+x

 

Philip Heaton - 2/27/2020

Hi Steve
Interesting that you mention an isolation transformer as as safety device for reverse polarity.  We contemplated fitting one as we have an aluminium boat but given both the weight and cost we went for a galvanic isolator - does this provide the same safety feature and therefore do I need to carry on testing for reverse polarity?  Disclaimer - in the event that I electrocute myself or some-one else you will not be held accountable by me ... cannnot speak for the missus though ...

Hi Philip,
My friends with metal boats believe that every metal boat should have an isolation transformer. Not having a metal boat, I have forgotten the details of their arguments, but believe it has something to do with the IT sitting guard between the shore power AC input and the boat’s AC system, thereby providing isolation from shore power limitations, from green wire connection to other boats (and the problems that can occur, corrosion, from other boats defective wiring) as well as all the benefits of a galvanic isolator.
I do not believe that a galvanic isolator will correct or in any way effect reverse polarization while I suspect an IT will correct faults in AC shore power systems such as this.
My best, Dick