AC and DC ground connection

[Westie]

Should the AC and DC grounds be connected together in the boat?
Right now there is no connection between the shore power AC ground and the DC ground. I am adding an inverter/charger and the manual says that the AC and DC grounds should be connected together. From a safety standpoint this makes sense. There is also a galvanic isolator installed so there is no reason not to connect them from a galvanic corrosion point of view.

Why would they not be connected together originally?

 

[fc3]

They probably are connected at one of the bus bars in the engine compartment.

 

[boatmailster]

Should the AC and DC grounds be connected together in the boat?
Right now there is no connection between the shore power AC ground and the DC ground. I am adding an inverter/charger and the manual says that the AC and DC grounds should be connected together. From a safety standpoint this makes sense. There is also a galvanic isolator installed so there is no reason not to connect them from a galvanic corrosion point of view.

Why would they not be connected together originally?

on newer boats they are connected together.
connect ohm meter between both ground buses to be sure that they are not connected already.

 

[Mr Salt]

When you do not have an inverter/charger on the boat the DC ground and the AC neutral would not be bridged. That keeps the two kinds of current seperate. When you put an inverter/charger on the boat you are "bridging" the two systems. AC is converted into DC current and DC current is converted AC. Thus a bridge is required because if something went wrong the 120 AC could kill you and you would not want it in the DC circuit.

The galvanic isolator controls the amount of voltage that can flow through the green wire, the secondary ground, to reduce the risk of low voltage current flows from or through the boat to the shore. That reduces the corrision interaction between the boat and the surrounding boats. If there were a heavy flow of current, say around 1 volt, well in excess of galvanic flows, the diodes open and allow the current to flow to the shore green ground.

Why isn't it there in the first place two reasons, it is not needed and second cost.

I hope that this helps

 

[Westie]

Thanks for the feedback guys. I know for sure that the grounds were not connected together anywhere. The AC system in my boat was quite basic, only a couple of outlets that the previous owner had screwed up the wiring to. I have since totally rewired the AC system and all the battery wiring. The only thin I wasn't sure about was the ground connections.
I am going to go ahead and connect them.