I have installed an Multiplus 3000/100/12 and only! connected 12v. I measure 230v between line and ground. Is this normal? 
asked
Line and ground, 230v
This is how electrics works... line powers neutral absorbs... if the function grounded neutral is active Use a rcd After to be Sure to be safe...
in the inside of the casing of the Victron a little picture shows the connections 
In the default configuration this is the correct operation. Neutal and Earth are bonded.
If you don't understand how or why earth systems work, then I'd urge you to consult with your local electrician for all of your high Voltage wiring requirements.
