Where to locate Galvanic Isolator

[Pelagic]

Originally Posted by Sailorlou

Your drawings are correct.

.....When you haul your boat out of the water the transformer is not required. The drawing you have for out of the water connection basically defeats the transformer and uses the shore power neutral to ground connection by connecting shore ground to ships ground.

Got it, .....but I was wondering WHY on the Drydock wiring they bypass the Isolation Transformer?

I guessed it may be in case of any welding going on, as they always ask me to disconnect batteries if welding stainless on my steel boat, or making a new transducer box.

Is there any other reason Victron advise you make this bypass?

[dkenny64]

Dotdun, thanks.. I was thinking along the same lines..
that way there is no reference..and no current.


connecting to shield within the isolation transformer..I would be interesting in hearing about the why??


I would put an Isolation transformer in my boat if I had room.. I had just enough room for a 4x6 heatsink with diodes for the galvanic isolator..


-dkenny64

[dkenny64]

Ahmet,


I argee that is why there should be a galvanic isolator between shore ground and the boats DC ground..yes? a direct connection would allow stray currents from the AC ground into one's boat.. FYI I measured 150ma on this wire using a current loop on my boat..before I install a galvanic isolator..no transformer.



so where does the boat AC ground fit in? anywhere? if one has an isolation transformer.


-dkenny64

[Ahmet Erkan]

Originally Posted by dkenny64

Ahmet,


I argee that is why there should be a galvanic isolator between shore ground and the boats DC ground..yes? a direct connection would allow stray currents from the AC ground into one's boat.. FYI I measured 150ma on this wire using a current loop on my boat..before I install a galvanic isolator..no transformer.



so where does the boat AC ground fit in? anywhere? if one has an isolation transformer.


-dkenny64

Hello dkenny64,
150mA AC current through the shore power grounding conductor is five times greater than the maximum permissible leakage so we have a problem here.
I recommend an ohms measurement with your multimeter. Unplug your shore power cable at the dock and measure ohms from the ground pin to the Neutral, it should be an open circuit. (ie infinite ohms)
If you read low ohms someone may have jumpered the neutral to ground on board which is not right. Find the jumper and remove it.

If you encounter other problems, start a new post and we will figure it out.

Boat's AC ground is typically a bussbar with conductors from common battery negative bus, engine block, metal thru hulls, shaft brush, lightning protection cables, metal tanks, any other large metal objects, etc. The shore power grounding conductor should also connect to the boats AC ground through the galvanic isolator.
If you don't already have a galvanic isolator, you can buy one for $300 or I can help you build the same for $10 or a truly superior one for $30 and it will work much better than the store bought galvanic isolator and would be much safer than the $1000 mis-wired isolation transformer.
Don't let them rip you off and sell you useless garbage my friend.
Ahmet

[a64pilot]

There has been so much incorrect data, and poor manners displayed I’m going to lock this thread and see what we can do to clean it up.