Originally Posted by transmitterdan
I strongly disagree. In fact it is the best practice. If the case is not connected to boat ground then there is the possibility of shock within the boat which is the most likely danger
. The case must not be allowed to be at a different potential than the boat ground and neutral.
Even if the shore hot comes in contact with the case you will not be shocked so long as you do not touch the case and shore ground at the same time. You would need really long arms to do that. The probability of shore hot contacting the case is remote
BTW, this fault condition is what can cause drownings in fresh water marinas
and why many marinas
are installing GFCI or whatever the acronym of the week is. It can also cause corrosion
to the boat. But this type of fault is many times less likely than the marina sparky criss-crossing hot and neutral. The iso transformer makes that mistake a non event which is why they are a great safety
In your lab it is easy to touch the case and earth ground at the same time. Thus the case must be earthed. In a boat it is nearly impossible to come in contact with both at the same time.
Hang on , firstly there is no code that suggests that local AC earth is established. ABYC don't mandate it.
Hence only through inadvertent means does the output E wire attempt to establish a true neutral.
Hence the shock hazard I mentioned was incoming hot ( shore) touching the traffo case. Since the shore power
is earth referenced and sea water
is a return path , in this case merely touching the case results in an unprotected shock ( again see the smart gauge web site. )
What I trying to establish , is that current
ABYC standards only use the traffo to provide galvanic isolation , no additional on board shock hazards are prevented by the transformer
In a europe
, its actually code forbidden to establish an on board ground with shore power
. aC and DC are not connected , so its much more likely that the output of the transformer is floating , this has actually issues for breakers , as no particular side is hot , both legs are. This would suggest that double pole breakers and RCDs are a must.